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History of Technology

(With a special mention of batteries)

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Heroes and Villains - A little light reading

Here you will find a brief history of technology. Initially inspired by the development of batteries, it covers technology in general and includes some interesting little known, or long forgotten, facts as well as a few myths about the development of technology, the science behind it, the context in which it occurred and the deeds of the many personalities, eccentrics and charlatans involved.

"Either you do the work or you get the credit" Yakov Zel'dovich - Russian Astrophysicist

Fortunately it is not always true.

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You may find the Search Engine, the Technology Timeline or the Hall of Fame quicker if you are looking for something or somebody in particular.

See also the timeline of the Discovery of the Elements

Go to the Year

The Inspiration - There's more to batteries than you might think


We think of a battery today as a source of portable power, but it is no exaggeration to say that the battery is one of the most important inventions in the history of mankind. Volta's pile was at first a technical curiosity but this new electrochemical phenomenon very quickly opened the door to new branches of both physics and chemistry and a myriad of discoveries, inventions and applications. The electronics, computers and communications industries, power engineering and much of the chemical industry of today were founded on discoveries made possible by the battery.


It is often overlooked that throughout the nineteenth century, most of the electrical experimenters, inventors and engineers who made these advances possible had to make their own batteries before they could start their investigations. They did not have the benefit of cheap, off the shelf, mass produced batteries. For many years the telegraph, and later the telephone, industries were the only consumers of batteries in modest volumes and it wasn't until the twentieth century that new applications created the demand that made the battery a commodity item.

In recent years batteries have changed out of all recognition. No longer are they simple electrochemical cells. Today the cells are components in battery systems, incorporating electronics and software, power management and control systems, monitoring and protection circuits, communications interfaces and thermal management.

The Content - It's not just about batteries. Scroll down and see what treasures you can discover.

History of Technology from the Bronze Age to the Present Day

Circa 3000 B.C. At the end of the fourth millennium B.C. the World was starting to emerge from the Stone Age.

Around 2900 B.C., Mesopotamians (from modern day Iraq), who had already been active for hundreds of years in primitive metallurgy extracting metals such as copper from their ores, led the way into the Bronze Age when artisans in the cities of Ur and Babylon discovered the properties of bronze and began to use it in place of copper in the production of tools, weapons and armour. Bronze is a relatively hard alloy of copper and tin, better suited for the purpose than the much softer copper enabling improved durability of the weapons and the ability to hold a cutting edge. The use of bronze for tools and weapons gradually spread to the rest of the World until it was eventually superceded by the much harder iron.

Mesopotamia, incorporating Sumer, Babylonia and Assyria, known in the West as the Cradle of Civilisation was located between the Tigris and Euphrates rivers (The name means "land between the rivers") in the so called Fertile Crescent stretching from the current Gulf of Iran up to modern day Turkey. (See Map of Mesopotamia)

Unfortunately this accolade ignores the contributions of the Chinese people and the Harappans of the Indus Valley, (Modern day Pakistan) who were equally "civilised" during this period practicing metallurgy (copper, bronze, lead, and tin) and urban planning, with civic buildings, baked brick houses, and water supply and drainage systems.

From around 3500 B.C. the Sumerians of ancient Mesopotamia developed the World's first written language. Called Cuneiform Writing from the Latin "cuneus", meaning "wedge", it was developed as a vehicle for commercial accounting transactions and record keeping. The writing was in the form of a series of wedge-shaped signs pressed into soft clay by means of a reed stylus to create simple pictures, or pictograms, each representing an object. The clay subsequently hardened in the Sun or was baked to form permanent tablets. By 2800 B.C. the script progressively evolved to encompass more abstract concepts as well as phonetic functions (representing sounds, just like the modern Western alphabet) enabling the recording of messages and ideas. For the first time news and ideas could be carried to distant places without having to rely on a messenger's memory and integrity.

Hieroglyphic script evolved slightly later in Egypt. Though the script appeared on vases and stone carvings, many important Egyptian historical scripts and records were written in ink, made from carbon black (soot) or red ochre mixed with gelatin and gum, applied with a reed pen onto papyrus. Produced from the freshwater papyrus reed, the papyrus scrolls were fragile and susceptible to decay from both moisture and excessive dryness and many of them have thus been lost, whereas the older, more durable clay cuneiform tablets from Mesopotamia have survived.

Historians seem to agree that the wheel and axle were invented around 3500 B.C. in Mesopotamia. Pictograms on a tablet dating from about 3200 B.C. found in a temple at Erech in Mesopotamia show a chariot with solid wooden wheels. Evidence from Ur indicates that the simpler potter's wheel probably predates the use of the axled wheel for transport because of the difficulty in designing a reliable mechanism for mounting the rotating wheel on a fixed hub or a rotating axle on the fixed load carrying platform.

Sumerian mathematics and science used a base 60 sexagesimal numeral system. 60 is divisible by 1,2,3,4,5,6,10,12,15,20,30 and 60 making it more convenient than using a base 10 decimal system when working with fractions. The Mesopotamians thus introduced the 60-minute hour, the 60-second minute and the 360-degree circle with each angular degree consisting of 60 seconds. The calendar adopted by the Sumerians, Babylonians and Assyrians was based 12 lunar months and seven-day weeks with 24-hour days. Since the average lunar month is 29.5 days, over 12 months this would produce a total of only 354 days as against a solar year of 365.25 days. To keep the calendar aligned to the seasons they added seven extra months in each period of 19 years, equivalent to the way we add an extra day in leap years. Despite decimalisation, we still use these sexagesimal measures today.

The Mesopotamians discovered glass, probably from glass beads in the slag resulting from experiments with refining metallic ores. They were also active in the development of many other technologies such as textile weaving, locks and canals, flood control, water storage and irrigation.

There are also claims that the Archimedes' Screw may have been invented in Mesopotamia and used for the water systems at the Hanging Gardens of Babylon.

2500 B.C. Sometimes known as the "Second oldest profession", soldering has been known since the Bronze Age (Circa 3000 to 1100 B.C.). A form of soldering to join sheets of gold was known to be used by the Mesopotamians in Ur. Fine metal working techniques were also developed in Egypt where filigree jewellery and cloisonné work found in Tutankhamun's tomb dating from 1327 B.C. was made from delicate wires which had been drawn through dies and then soldered in place.

Egypt was also home to Imhotep the first man of science in recorded history. He was the world's first named architect and administrator who around 2725 B.C. built the first pyramid ever constructed, the Stepped Pyramid of Saqqara. Papyri were unearthed in the nineteenth century dating from around 1600 B.C. and 1534 B.C. both of which refer to earlier works attributed to Imhotep. The first outlines surgical treatments for various wounds and diseases and the second contains 877 prescriptions and recipes for treating a variety of medical conditions making Imhotep the world's first recorded physician. Other contemporary papyri described Egyptian mathematics. Egyptian teachings provided the foundation of Greek science and although Imhotep's teachings were known to the Greeks, 2200 years after his death, they assigned the honour of Father of Medicine to Hippocrates.

2300 B.C. The earliest evidence of the art of stencilling used by the Egyptians. Designs were cut into a sheet of papyrus and pigments were applied through the apertures with a brush. The technique was reputed to have been in use in China around the same time but no artifacts remain.

2100-1600 B.C. The Xia dynasty in China perfected the casting of bronze for the production of weapons and ritual wine and food vessels, reaching new heights during the Shang dynasty (1600-1050 B.C.).

Circa 2000 B.C. The process for making wrought iron was discovered by the Hittites, in Northern Mesopotamia and Southern Anatolia (now part of Eastern Turkey), who heated iron ore in a charcoal fire and hammered the results into wrought (worked) iron. See more about wrought iron

1300 B.C. Fine wire also made by the Egyptians by beating gold sheet and cutting it into strips. Recorded in the Bible, Book of Exodus, Chapter 39, Verse 3, - "And they did beat the gold into thin plates, and cut it into wires, to work it. in the fine linen, with cunning work."

The Egyptians also made coarse glass fibres as early as 1600 B.C. and fibers survive as decorations on Egyptian pottery dating back to 1375 B.C.

1280 B.C. Around this date, after his escape from Egypt, Moses ordered the construction of the Ark of the Covenant to house the tablets of stone on which were written the original "Ten Commandments". Its construction is described in great detail in the book of Exodus and according to the Bible and Jewish legend it was endowed with miraculous powers including emitting sparks and fire and striking dead Aaron's sons and others who touched it. It was basically a wooden box of acacia wood lined with gold and also overlaid on the outside with gold. The lid was decorated with two "cherubim" with outstretched wings. In 1915 Nikola Tesla, in an essay entitled "The Fairy Tale of Electricity" promoting the appreciation of electrical developments, proposed what seemed a plausible explanation for some of the magical powers of the Ark. He claimed that the gold sheaths separated by the dry acacia wood effectively formed a large capacitor on which a static electrical charge could be built up by friction from the curtains around the Ark and this accounted for the sparks and the electrocution of Aaron's sons.

Recent calculations have shown however that the capacitance of the box would be in the order of 200 pico farads and such a capacitor would need to be charged to 100,000 volts to store even 1 joule of electrical energy, not nearly enough to cause electrocution. It seems Tesla's explanation was appropriately named.

800 B.C. The magnetic properties of the naturally occurring lodestone were first mentioned in Greek texts. Also called magnetite, lodestone is a magnetic oxide of iron (Fe3O4) which was mined in the province of Magnesia in Thessaly from where the magnet gets its name. Lodestone was also known in China at that time where it was known as "love stone" and is in fact quite common throughout the world.

Surprisingly although they were aware of its magnetic properties, neither the Greeks nor the Romans seem to have discovered its directive property.

Eight hundred years later in 77 A.D., the somewhat unscientific Roman chronicler of science Pliny the Elder, completed his celebrated series of books entitled "Natural History". In it, he attributed the name "magnet" to the supposed discoverer of lodestone, the shepherd Magnes, "the nails of whose shoes and the tip of whose staff stuck fast in a magnetic field while he pastured his flocks". Thus another myth was born. Pliny was killed during the volcanic eruption of Mount Vesuvius near Pompeii in A.D. 79 but his "Natural History" lived on as an authority on scientific matters up to the Middle Ages.

600 B.C. The Greek philosopher and scientist, Thales of Miletus (624-546 B.C.) - one of the Seven Wise Men of Greece - was the first thinker to attempt to explain natural phenomena by means of some underlying scientific principle rather than by attributing them to the whim of the Gods - a major departure from previous wisdom and the foundation of scientific method, frowned upon by Aristotle but rediscovered during the Renaissance and the Scientific Revolution.

He travelled to Egypt and the city state of Babylon in Mesopotamia (now modern day Iraq) and is said to have brought Babylonian mathematics back to Greece. The following rules are attributed to him:

  • Any angle inscribed in a semicircle is a right angle. Known as the Theorem of Thales it was however known to the Babylonians 1000 years earlier.
  • A circle is bisected by any diameter.
  • The base angles of an isosceles triangle are equal.
  • The opposite angles formed by two intersecting lines are equal.
  • Two triangles are congruent (equal shape and size) if two angles and a side are equal.
  • The sides of similar triangles are proportional

Using the concept of similar triangles he was able to calculate the height of pyramids by comparing the size of their shadows with smaller, similar triangles of known dimensions. Similarly he calculated the distance to ships at sea by noting the azimuth angle of the ship from two widely spaced observation points a known distance apart on the shore and scaling up the distance to the ship from the dimensions of smaller similar triangle.

Thales also demonstrated the effect of static electricity by picking up small items with an amber rod made of fossilised resin which had been rubbed with a cloth. He also noted that iron was attracted to lodestone.

Thales left no writings and knowledge of him is derived from an account in Aristotle's Metaphysics written nearly 300 years later and itself subject to numerous subsequent copies and translations.

530 B.C. Pythagoras of Samos (580-500 B.C.) an Ionian Greek, is considered by many to be the Father of Mathematics. Like Thales, he had travelled to Egypt and Babylon where he studied astronomy and geometry. His theorem. "In a right-angled triangle the square on the hypotenuse is equal to the sum of the squares on the other two sides" is well known to every schoolchild.

Around 530 BC, he moved to Croton, in Magna Graecia, where he set up a religious sect. His cult-like followers, were enthralled by numbers such as prime numbers and irrational numbers and considered their work to be secret and mystical. Prior to Pythagoras, mathematicians had dealt only in whole numbers and fractions or ratios but Pythagoras brought them into contact with √2 and other square roots which were not rational numbers.

Pythagoreans also discovered the Divine Proportion, also called the Golden Mean or Golden Ratio, an irrational number Φ (Phi) = (√5+1)/2 ≈ 1.618 which has fascinated both scientists and artists ever since.

(See examples of The Divine Proportion).

None of Pythagoras writings have survived and knowledge of his life and works is based on tradition rather than verified facts.

Circa 500 B.C. Cast iron was produced for the first time by the Chinese during the Zhou dynasty (1046-256 B.C.). Prior to that, it had not been possible to raise the temperature of the ore sufficiently to melt the iron and the only available iron was wrought iron created by heating iron ore in a furnace with carbon as the reducing agent and hammering the resulting spongy iron output. Furnaces of the day could reach temperatures of about 1300°C which was enough to melt copper whose melting point is 1083°C but not enough to melt iron whose melting point is 1528°C. By a combination of the addition of phosphorus to the ore which reduced its melting point, the use of a bellows to pump air through the ore to aid the exothermic reduction process and the use of improved high temperature refractory bricks forming the walls of the furnace to withstand the heat, the Chinese were able to melt the iron and cast it into functional shapes ranging from tools and pots and pans to heavy load bearing constructional members as well as fine ornamental pieces.

Cast iron was not produced in Europe till around 1400 A.D.. Gun-barrels and bullets were the first cast iron products to be manufactured but it was not until 1709 when Abraham Darby introduced new production methods that low cost, volume production was achieved.

See more about Chinese Inventions.

460 B.C. Another Greek philosopher Democritus of Abdera developed the idea that matter could be broken down into very small indivisible particles which he called atoms. Subsequently Aristotle dismissed Democritus' atomic theory as worthless and Aristotle's views tended to prevail. It was not until 1803 that Democritus' theory was resurrected by John Dalton.

350 B.C. The Greek philosopher and scientist Aristotle (384-322 B.C.) provided "scientific" theories based on pure "reason" for everything from the geocentric structure of the cosmos down to the four fundamental elements earth, fire, air and water.

Aristotle believed that knowledge should be gained by pure rational thought and had no time for mathematics which he regarded only as a calculating device. Neither did he support the experimental method of scientific discovery, espoused by Thales, which he considered inferior. In his support it should be mentioned that the range of experiments he could possibly undertake was limited by the lack of suitable accurate measuring instruments in his time and it was only in the seventeenth century during the Scientific Revolution that such instruments started to become available.

Unfortunately Aristotle's "rational" explanations were subsequently taken up by St Thomas Aquinas (1225-1274) and espoused by the church which for many years made it difficult, if not dangerous, to propose alternative theories. Aristotle's theories of the cosmos and chemistry thus held sway for 2000 years hampering scientific progress until they were finally debunked by Galileo, Newton and Lavoisier who showed that natural phenomena could be described by mathematical laws.

See also Gilbert (1600), Descartes (1644) and Von Guericke (1663) and the Scientific Revolution.

Aristotle was also a tutor to the young Alexander the Great

Like many sources from antiquity, Aristotle's original manuscripts have been destroyed or lost and we know of Aristotle's works via series of copies and translations from the Greek into Arabic, then from Arabic into Latin and finally from Latin into English and other modern languages. There's much that could have been lost, changed or even added in the translations.

332 B.C. Alexander the Great conquered Egypt and ordered the building of a new city on the Egyptian, Nile delta named after himself - Alexandria. When he died in 323 BC his kingdom was divided between three of his generals, with Egypt going to Ptolemy (367–283 B.C.) who later declared himself King Ptolemy I Soter (not to be confused with Claudius Ptolemy (90-168 A.D.)) and founded a new dynasty, replacing the Pharaohs, which lasted until the Roman conquest of 30 B.C.

Ptolemy Soter's grandest building project in the new capital was the Musaeum or "Temple of the Muses" (from which we get the modern word "museum") which he founded around 306 B.C. A most important part of the Musaeum was the famous Library of Alexandria, which he conceived, and which was carried through by his son Ptolemy II Philadelphus, with the object of collecting all the world's knowledge. Most of the staff were occupied with the task of translating works onto papyrus and it is estimated (probably over-estimated) that as many as 700,000 scrolls, the equivalent of more than 100,000 modern printed books, filled the library shelves.

Great thinkers were invited to Alexandria to establish an academy at the library turning it into a major centre of scholarship and research. Euclid was one of the first to teach there. Ultimately the library overshadowed the Musaeum in importance and interest becoming perhaps the oldest university in the world.

It was at the library that:

  • Euclid developed the rules of geometry based on rigorous proofs. His mathematical text was still in use after 2000 years.
  • Archimedes invented the a water pump based on a helical screw, versions of which are still in use today. (The actual date of this invention is however disputed).
  • Eratosthenes measured the diameter of the Earth.
  • Hero invented the aeolipile, the first reaction turbine.
  • Claudius Ptolemy wrote the Almagest, the most influential scientific book about the nature of the Universe for 1,400 years.
  • Hypatia, the first woman scientist and mathematician invented the hydrometer, before she met her untimely end during Christian riots.

Alas the ancient library is no more. Four times it was devastated by fire, accidental or deliberate, during wars and riots and historians disagree about who were the major culprits, their motives and the extent of the damage in each case.

  • 48 B.C. Damage caused during the Roman conquest of Egypt by Julius Caesar
  • 272 A.D. An attack on Queen Zenobia of Palmyra by Roman Emperor Aurelian
  • 391 A.D. An edict of the Emperor Theodosius I made paganism illegal and Patriarch Theophilus of Alexandria ordered demolition of heathen temples. This was followed by Christian riots the same year and 415 A.D..
  • 639 A.D. The Muslim conquest of Alexandria by General Amr ibn al 'Aas leading the army of Caliph Omar of Baghdad.

But even without the wars, the delicate papyrus scrolls were apt to disintegrate with age and what was left of the library eventually succumbed to the ravages of major earthquakes in Crete in A.D. 365 and 1303 A.D. which caused tsunamis which in turn devastated Alexandria.

300 B.C. Fl Greek mathematician Euclid of Alexandria (Circa 325-265 B.C.) a great organiser and logician, taught at the great Library of Alexandria and took the current mathematical knowledge of his day and organised it into a manuscript consisting of thirteen books now known as Euclid's Elements. Considered by many to be the greatest mathematics text book ever written it has been used for over 2000 years. Nine of these books deal with plane and solid geometry, three cover number theory, one (book 10) concerns incommeasurable lengths which we would now call irrational numbers.

Proof, Logic and Deductive Reasoning

The "Elements" were not just about geometry, Euclid's theorems and conclusions were backed up by rigorous proofs based on logic and deductive reasoning and he was one of the first to require that mathematical theories should be justified by such proofs.

An example of the type of deductive reasoning applied by Euclid is the logical step based on the logical principle that if premise A implies B, and A is true, then B is also true, a principle that mediaeval logicians called modus ponens (the way that affirms by affirming). A classical example of this is the conclusion drawn from the following two premises: A: "All men are mortal" and B: "Socrates is a man" then the conclusion C: "Socrates is mortal" is also true.

In this manner Euclid started with a small set of self evident axioms and postulates and used them to produce deductive proofs of many other new propositions and geometric theorems. He wrote about plane, solid and spherical geometry, perspective, conic sections, and number theory applying rigorous formal proofs and showed how these propositions fitted into a logical system. His axioms and proofs have been a useful set of tools for many subsequent generations of mathematicians, demonstrating how powerful and beneficial deductive reasoning can be.

An example of Euclid's logical deduction is the method of exhaustion which was used as a method of finding the area of an irregular shape by inscribing inside it a sequence of n regular polygons of known area whose total area converges to the area of the given containing shape. As n becomes very large, the difference in area between the given shape and the n polygons it contains will become very small. As this difference becomes ever smaller, the possible values for the area of the shape are systematically "exhausted" as the shape and the corresponding area of the series of polygons approaches the given shape. This sets a lower limit to the possible area of the shape.

The method of exhaustion used to find the area of the shape above is a special case of of proof by contradiction, known as reductio ad absurdum which seeks to demonstrate that a statement is true by showing that a false, untenable, or absurd result follows from its denial, or in turn to demonstrate that a statement is false by showing that a false, untenable, or absurd result follows from its acceptance.

In the case above this means finding the area of the shape by first comparing it to the area of a second region inside the shape (which can be "exhausted" so that its area becomes arbitrarily close to the true area). The proof involves assuming that the true area is less than the second area, and then proving that assertion false. This gives a lower limit for the area of the shape under consideration.

Then comparing the shape to the area of a third region outside of the shape and assuming that the true area is more than the third area, and proving that assertion is also false. This gives an upper limit for the area of the shape.

No original records of Euclid's work survive and the oldest surviving version of "The Elements" is a Byzantine manuscript written in A.D. 888. Little is known of his life and the few historical references to Euclid which exist were written centuries after his death, by Greek mathematician Pappus of Alexandria around 320 A.D. and philosopher and historian Proclus around 450 A.D.

According to Proclus, when the ruler Ptolemy I Soter asked Euclid if there was a shorter road to learning geometry than through the Elements, Euclid responded "There is no royal road to geometry".

269 B.C. The greatest mathematician and engineer in antiquity, the Greek Archimedes of Syracuse (287-212 B.C.) began his formal studies at the age of eighteen when he was sent by his father, Phidias, a wealthy astronomer and kinsman of King Hieron II of Syracuse, to Egypt to study at the school founded by Euclid in the great Library of Alexandria. It kept him out of harm's way in the period leading up to the first Punic war (264-241 B.C.) between Carthage and Rome when Sicily was still a colony of Magna Graecia, vulnerably situated in strategic territory between the two adversaries. Syracuse initially supported Carthage, but early in the war Rome forced a treaty of alliance from king Hieron that called for Syracuse to pay tribute to the Romans. Returning to Syracuse in 263 B.C. Archimedes became a tutor to Gelon, the son of King Hieron.

Archimedes' Inventions

Archimedes was known as an inventor, but unlike the empirical designs of his predecessors, his inventions were the first to be based on sound engineering principles.

He was the world's first engineer, the first to be able to design levers, pulleys and gears with a given mechanical advantage thus founding the study of mechanics and the theory of machines.

Archimedes also founded the studies of statics and hydrostatics and was the first to elucidate the principle of buoyancy and to use it in practical applications.

  • Though he did not invent the lever, he explained its mechanical advantage, or leverage, in his work "On the Equilibrium of Planes" and is noted for his claim "Give me a place to stand and a long enough lever and I can move the Earth".
  • Archimedes' explanation of the theory of the lever is based on the principle of balancing the input and output torques about the fulcrum of the device so that, the input force multiplied by its distance from the fulcrum, is equal to the weight (or downward force) of the load multiplied by its distance from the fulcrum. In this arrangement, the distance moved by each force is proportional to its distance from the fulcrum. Thus a small force moving a long distance can lift a heavy load over a small distance and the mechanical advantage is equal to the ratio of the distances from the fulcrum of the points of application the input force and the output force. He applied similar reasoning to explain the operation of compound pulleys and gear trains, in the latter case using angular displacement in place of linear displacement.

    We would now relate this theory to the concepts of work done, potential energy and the conservation of energy. See also hydraulic, mechanical advantage described by Pascal.

  • He is credited by the Greek historian Plutarch (46-120 A.D.), with inventing the block and tackle / compound pulley to move ships and other heavy loads. The use of a simple, single-sheaved pulley to change the direction of the pull, for drawing water and lifting loads had been known for many years. This device did not provide any mechanical advantage, but Archimedes showed that a multi-sheaved, compound pulley could provide a mechanical advantage of n where n is the number of sheaves in the pulley mechanism.
  • Similarly, Archimedes was familiar with gearing, which had been mentioned in the writings of Aristotle about wheel drives and windlasses around 330 B.C., and was able to calculate the mechanical advantage provided by the geared mechanisms of simple spur gears. Archimedes is however credited with the invention of the worm gear which not only provided much higher mechanical advantage, it also had the added advantage that the "worm", actually a helical screw, could easily rotate the gear wheel but the gear wheel could not easily, if at all, rotate the worm. This gave the mechanism a ratchet like, or braking, property such that heavy loads would not slip back if the input force was relaxed.
  • It is said that he invented a screw pump, known after him as the Archimedes' Screw, for raising water by means of a hollow wooden pipe containing a close fitting wooden, helical screw on a long shaft turned by a handle at one end. When the other end was placed in the water to be raised and the handle turned, water was carried up the tube by the screw and out at the top. However such devices probably predated Archimedes and were possibly used in the Hanging Gardens of Babylon. The Archimedes' Screw is still used today as a method of irrigation in some developing countries.
  • He also designed winches, windlasses and military machines including catapults, trebuchets and siege engines.
  • It is claimed by some that Archimedes invented the odometer but this is more likely to be the work of Vitruvius who described its working details.
  • Fanciful claims have also been made that he designed gear mechanisms for moving extremely heavy loads, an Iron Claw to lift ships out of the water causing them to break up and a Death Ray to set approaching ships on fire. See more about these claims below.

Archimedes' Mathematics

While Archimedes was famous for his inventions, his mathematical writings were equally important but less well known in antiquity. Mathematicians from Alexandria read and quoted him, but the first comprehensive compilation of his work was not made until Circa. 530 A.D. by Isidore of Miletus.

  • Archimedes was able to use infinitesimals in a way that is similar to modern integral calculus. Through proof by contradiction (reductio ad absurdum), he could give answers to problems to an arbitrary degree of accuracy, while specifying the limits within which the answer lay.
  • Though mathematicians had been aware for many years that the ratio π between the circumference and the diameter of a circle was a constant, there were wide variations in the estimations of its magnitude. Archimedes calculated its value to be 3.1418, the first reasonably accurate value of this constant.
  • He did it by using the method of exhaustion to calculate the circumference of a circle rather than the area and by dividing the circumference by the diameter he obtained the value of π. First he drew a regular hexagon inside a circle and computed the length of its perimeter. Then he improved the accuracy by progressively increasing the number of sides of the polygon and calculating the perimeter of the new polygon with each step. As the number of sides increases, it becomes a more accurate approximation of a circle. At the same time, by circumscribing the circle with a series of polygons outside of the circle, he was able to determine an upper limit for the perimeter of the circle. He found that with a 96 sided polygon the lower and upper limits of π calculated by his method were given by:

    223/71 < π < 22/7

    In modern decimal notation this converts to:

    3.1408 < π < 3.1428

    The value of π calculated by Archimedes is given by the average between the two limits and this is 3.1418 which is within 0.0002 of its true value of 3.1416.

  • More generally, Archimedes calculated the area under a curve by imagining it as a series of very thin rectangles and proving that the sum of the areas of all the rectangles gave a very close approximation to the area under the curve. Using the method of exhaustion he showed that the approximation was neither greater nor smaller than the area of the figure under consideration and therefore it must be equal to the true area. He was thus able to calculate the areas and volumes of different shapes and solids with curved sides. This method anticipated the methods of integral calculus introduced nearly 2000 years later by Newton and Leibniz.
  • He was also able to calculate the sum of a geometric progression.
  • He proved that the area of a circle was equal to π multiplied by the square of the radius of the circle (πr2) and that the volume and surface area of sphere are 2/3 of a cylinder with the same height and diameter.
  • Thus he showed that the surface area of a sphere with radius r is given by: A = 4 π r2 and the volume of a sphere with radius r is given by: V= 4/3π r3 which he regarded as one of his proudest achievements.

  • He also developed fundamental theorems concerning the determination of the centre of gravity of plane figures.
  • In an attempt to calculate how many grains of sand it would take to fill the Universe, Archimedes devised a number system which he called the Sand Reckoner to represent the very large numbers involved. Based on the largest number then in use called the myriad equal to 10,000 he used the concept of a myriad-myriads equal to 108. He called the numbers up to 108 "first numbers" and called 108 itself the "unit of the second numbers". Multiples of this unit then became the second numbers, up to this unit taken a myriad-myriad times, 108·108=1016. This became the "unit of the third numbers", whose multiples were the third numbers, and so on so that the largest number became (108) raised to the power (108) which in turn is raised to the power (108).

Myths and Reality

As with many great men of antiquity, few if any, contemporary records of Archimedes works remain and his reputation has been embellished by historians writing about him many years after his death, or trashed by artists, ignorant of the scientific principles involved, attempting to illustrate his ideas. This is probably the case with four of the oft quoted anecdotes about his work.

  • It is claimed that Archimedes used a mirror or mirrors on the shore to focus the Sun's rays, the so called Death Rays onto attacking ships to destroy them by setting them on fire. (The Greeks had much more practical incendiary missiles available to them at the time and catapults to throw them long distances)

  • Similarly it is reported that Archimedes used his compound pulley system connected to an Iron Claw suspended from a beam to lift the prows of attacking ships out of the water causing them to break up or capsize and sink. (The ships would have to be almost on the beach, directly in front of the defensive claw, to be in range of these machines.)

  • He was also familiar with geared mechanisms and it was claimed by third century historian, Athenaeus, that Archimedes' systems of winches and pulleys would enable a few men to launch a huge boat into the sea or to carry it on land. These mechanisms were illustrated by Gian Maria Mazzucchelli in his 1737 biography of Archimedes. It is quite clear from the drawings that the wooden gear wheels would have been unable to transmit the power required and the tensile strength of the ropes employed is also questionable.

  • Over the years, in the absence of written records, other artists and illustrators have tried to depict Archimedes devices and mechanisms. Examples of how the artists have imagined these devices are shown in the page about Archimedes' Machines

  • The most widely known anecdote about Archimedes is the Eureka story told two centuries later by the Roman architect and engineer Vitruvius. According to Vitruvius, King Hieron II had supplied a pure gold ingot to a goldsmith charged with making a new crown. The new crown when delivered weighed the same as the ingot supplied but the King wanted Archimedes to determine whether the goldsmith had adulterated the gold by substituting a portion of silver. Archimedes was aware that silver is less dense than gold so he would be able to to determine whether some of the gold had been replaced by silver by checking the density. He had a balance to check the weight, but how could he determine the volume of an intricately designed crown without melting it down or otherwise damaging it?
  • While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realised that this effect could be used to determine the volume of the crown. By immersing the crown in water, the volume of water displaced would equal the volume of the crown. If any of the gold had been replaced by silver or any other less dense metal, then the crown would displace more water than a similar weight of pure gold. EUREKA!!!. It was reported that Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" (Greek: meaning "I have found it!").

    The test was conducted successfully, proving that silver had indeed been mixed in. There is no record of what happened to the goldsmith. It is claimed today that the change in volume would probably have been so small as to be undetectable by the apparatus available to Archimedes at the time.

    There is no question however that he devised a method of measuring the volume of irregularly shaped objects and also understood the principle of buoyancy and its use for comparing the density of the materials used in different objects, but the story of him running naked through the streets is probably apocryphal.

All of these stories probably contain a major element of truth and it would not be surprising that Archimedes was well aware of, and had publicised, the theoretical possibilities involved in these schemes, but whether they could have actually been successfully implemented with the available technology and materials of the day is open to question. The principles were correct but the scale and effectiveness of the devices described in biographies written hundreds of years later was doubtful. There is unfortunately no corroborating evidence to back up these later descriptions of the military exploits. If the naval siege defences had been so successful, why would they not have been subsequently adopted as standard practice and why did they not appear in historical accounts of the battles?

Death of Archimedes

By 215 B.C. Hostilities between Carthage and Rome flared up once more in the second Punic war and in 214 B.C. and Syracuse sided once more with the Carthaginians and so came under siege by the Romans under General Marcus Claudius Marcellus. Archimedes skills in designing military machines and mechanical devices were well known, even to the Romans, and were called upon in the defence of Syracuse during these hostilities.

Greek historian Plutarch (C. 46 – 120 A.D.) gave two accounts of Archimedes' death in 212 B.C. when Roman forces eventually captured the city after a two year siege. The first describes how Archimedes was contemplating a mathematical problem on a diagram he had drawn in the dust on the ground when he was approached by a Roman soldier who commanded him to come and meet General Marcellus who considered the great inventor to be a valuable scientific asset who should not be harmed. But Archimedes declined, saying that he had to finish working on the problem. The soldier was enraged by this, and ran him through with his sword, much to the annoyance of Marcellus.

The second account explains that Archimedes was killed by a soldier while attempting to rob him of his valuable mathematical instruments.

Recent examination of all the accounts by both Carthaginian and Roman historians of the details of Archimedes' death have however reached a different conclusion. As we know, history is often written by the winners. The counter view is that Archimedes' death was the state-sponsored assassination of an enemy of Rome, a key player, whose inventions were vital to the defence of Syracuse. The nations were at war. Why would Archimedes be so oblivious to the danger he was in? Marcellus' feigned sorrow and anger after the event were a cover for his guilt at ordering the death of the World's greatest scientist at the time.

250 B.C. The Baghdad Battery - In 1936 several unusual earthenware jars, dating from about 250 B.C., were unearthed during archeological excavations at Khujut Rabu near Baghdad. A typical jar was 130 mm (5-1/2 inches) high and contained a copper cylinder, the bottom of which was capped by a copper disk and sealed with bitumen or asphalt. An iron rod was suspended from an asphalt stopper at the top of the copper cylinder into the centre of the cylinder. The rod showed evidence of having been corroded with an acidic agent such as wine or vinegar. 250 BC corresponds to the Parthian occupation of Mesopotamia (modern day Iraq) and the the jars were held in Iraq's State Museum in Baghdad. (Baghdad was not founded until 762 A.D.) 1938 they were examined by German archeologist Wilhelm König who concluded that they were Galvanic cells or batteries supposedly used for gilding silver by electroplating. A mysterious anachronism. Backing up his claim, König also found copper vases plated with silver dating from earlier periods in the Baghdad Museum and other evidence of (electro?)plated articles from Egypt. Since then, several replica batteries have been made using various electrolytes including copper sulphate and grape juice generating voltages from half a Volt to over one Volt and they have successfully been used to demonstrate the electroplating of silver with gold. One further, more recent, suggestion by Paul T. Keyser a specialist in Neat Eastern Studies from the University of Alberta is that the galvanic cells were used for analgesia. There is evidence that electric eels had been used to numb an area of pain, but quite how that worked with such a low voltage battery is not explained. Apart from that, no other compelling explanation of the purpose of these artifacts has been proposed and the enigma still remains.

Despite warnings about the safety of these priceless articles before the 2003 invasion of Iraq, they were plundered from the museum during the war and their whereabouts is now unknown.

A nice and oft repeated story but there is a counter view about their purpose.

The Parthians were nomadic a nomadic tribe of skilled warriors and not noted for their scientific achievements. The importance of such an unusual electrical phenomenon seems to have gone completely unrecorded within the Parthian and contemporary cultures and then to have been completely forgotten despite extensive historical records from the period.

There are also some features about the artifacts themselves which do not support the battery theory. The asphalt completely covers the copper cylinder, electrically insulating it so that no current could be drawn without modifying the design and no wires, conductors, or any other sort of electrical equipment associated with the artifacts have been found. Furthermore the asphalt seal forms a perfect seal for preventing leakage of the electrolyte but it would be extremely inconvenient for a primary galvanic cell which would require frequent replacement of the electrolyte. As an alternative explanation for these objects, it has been noted that they resemble storage vessels for sacred scrolls. It would not be at all surprising if any papyrus or parchment inside had completely rotted away, perhaps leaving a trace of slightly acidic organic residue.

240 B.C. Greek mathematician Eratosthenes(276-194 B.C.) of Cyrene (now called Shahhat, Libya), the third chief librarian at the Library of Alexandria and contemporary of Archimedes calculated the Circumference of the Earth. Considering the tools and knowledge available at the time, Eratosthenes results are truly brilliant. Equipped with only a stick, he did not even need to leave Alexandria to make this remarkable breakthrough. Not only did he know that the Earth was spherical, 1700 years before Columbus was born, he also knew how big it was to an accuracy within 1.5%. See Eratosthenes Method and Calculation.

He invented the discipline of geography including the terminology still used today and created the first map of the world incorporating parallels and meridians, (latitudes and longitudes) based on the available geographical knowledge of the era. He was also the first to calculate the tilt of the Earth's axis (again with remarkable accuracy) and he deduced that the calendar year was 365 1/4 days long and was first to suggest that every four years there should be a leap year of 366 days.

Eratosthenes also devised a way of finding prime numbers known as the sieve. Instead of using trial division to sequentially test each candidate number for divisibility by each prime which is a very slow process, his system marks as composite (i.e. not prime) the multiples of each prime, starting with the multiples of 2, then 3 and continues this iteratively so that they can be separated out. The multiples of a given prime are generated as a sequence of numbers starting from that prime, with constant difference between them which is equal to that prime.

220-206 B.C. The magnetic compass was invented by the Chinese during the Qin (Chin) Dynasty, named after China's first emperor Qin Shi Huang di, the man who built the wall. It was used by imperial magicians mostly for geomancy (Feng Shui and fortune telling) but the "Mighty Qin's" military commanders were supposed to be the first to use a lodestone as a compass for navigation. Chinese compasses point south.

See more about Chinese Inventions.

206 B.C. - 220 A.D. During the Han Dynasty, Chinese historian Ban Gu recorded in his Book of Han the existence of pools of "combustible water", most likely petroleum, in what is now China's Shaanxi province. During the same period, in Szechuan province, natural gas was also recovered from what they called "fire wells" by deep drilling up to several hundred feet using percussion drills with cast iron bits. These fuels were used for domestic heating and for extracting metals from their ores (pyrometallurgy), for breaking up rocks as well as for military incendiary weapons. Decorative oil lamps from the period have also been discovered.

Percussion drilling involves punching a hole into the ground by repeatedly raising and dropping a heavy chisel shaped tool bit into the bore hole to shatter the rock into small pieces which can be removed. The drill bit is raised by a cable and pulley system suspended from the top of a wooden tower called a derrick.

The fuels were later named in Chinese as shíyóu rock oil by Shen Kuo just as the word petroleum is derived from the latin petra rock and oleum oil.

It was over 2000 years before the first oil well was drilled by Edwin Drake in the USA and he used the same percussion drilling method as the Chinese.

See more about Chinese Inventions.

140 - 87 B.C. Paper was first produced in China in the second century B.C.. Made by pounding and disintegrated hemp fibres, rags and other plant fibres in water followed by drying on a flat mould, the paper was thick and coarse and surprisingly it was not used for writing but for clothing, wrapping, padding and personal hygiene. The oldest surviving piece of paper was found in a tomb near Xian and dates from between 140 B.C. to 87 B.C. and is inscribed with a map.

The first paper found with writing on it was discovered in the ruins of an ancient watch tower and dates from 105 A.D. The development of this finer paper suitable for writing is attributed to Cai Lun, a eunuch in the Imperial court during the Han dynasty (202 B.C. - A.D. 220).

Paper was an inexpensive new medium which provided a simple means of communicating accurately with others who were not present without the danger of "Chinese whispers" corrupting the message, but more importantly, it enabled knowledge to be spread to a wider population or recorded for use by future generations. A simple invention which, like the printing press, brought enormous benefits to society.

See more about Chinese Inventions.

27 B.C. - 5th Century A.D. The Roman Empire. The Romans were great plumbers but poor electricians.

The Romans were deservedly renowned for their civil engineering - buildings, roads, bridges, aqueducts, central heating and baths. Surprisingly however, in 500 years, they didn't advance significantly on the legacies of mathematics and scientific theories left to them by the Greeks. Fortunately, the works of the Greek philosophers and mathematicians were preserved by Arab scholars who translated them into Arabic.

Circa 15 B.C. Some time between 27 B.C and 15 B.C. Roman architect and military engineer, Marcus Vitruvius Pollio, completed "De Architectura" or "On Architecture: The Ten Books on Architecture". It is a comprehensive manual for architects covering the principles of architecture, education and training, town planning, environment, structures, building materials and construction methods, design requirements for buildings intended for different purposes, proportions, decorative styles, plans for houses, heating, acoustics, pigments, hydraulics, astronomy and a ranges of machinery and instruments.

His philosophies about architecture are summed up in the Vitruvian Virtues that a structure must exhibit the three qualities of firmitas, utilitas, venustas - meaning that it must be solid, useful and beautiful.

Included in Book 10 of the study are designs for military and hydraulic machines, including pulleys and hoists and designs for trebuchets, water wheels and armoured vehicles which have had an undeniable influence on the inventions of Leonardo da Vinci.

Amongst these designs are instructions for the design of an odometer which Vitruvius called a "hodometer". It consisted of a cart with a separate, large wheel of known circumference mounted in a frame. The large wheel was connected through the intermediate gear wheel of a reduction gear mechanism to a horizontal disk with a series of holes around its rim each containing a small pebble. A single hole in the housing of the horizontal disk allowed a pebble to fall through into a container below when it arrived above the hole. As the cart was pushed along the ground, one pebble would fall into the container for each revolution of the intermediate gear wheel. The distance traveled could be calculated by counting the number of pebbles in the container and multiplying by the circumference of the large wheel and the gear ratio. Vitruvius also proposed a marine version of his device in which the distance was calculated from the rotation of paddles.

There are some who attribute the design of the odometer to Archimedes, but there is no strong evidence to support this.

Unfortunately none of the original illustrations from "De Architectura" have survived. Nevertheless the books have deeply influenced classical architects from the Renaissance through to the twentieth century. He was perhaps a little too influential though, through no fault of his own, since his style was so sublime that it captured public taste, stifling further innovation and generations of architects merely copied his ideas rather than developing alternative styles of their own.

Vitruvius has been called the world's first engineer to be known by name.

1 B.C.

1 A.D.

Circa 50 AD In the first century A.D. several spectacular aqueducts were built by Roman Engineers and though many of them are still standing and in some cases still in use, there are unfortunately no records of who actually designed and built them. Two which stand out are the Pont du Gard near Nimes in France, the other at Segovia in Spain.

(See pictures of these two Roman Aqueducts)

In the absence of records the design and construction of the Pont du Gard has been attributed to Marcus Agrippa, the adopted son-in-law of Emperor Augustus at around the year 19 B.C. However recent excavations and coins depicting the Emperor Claudius (41-54 A.D.) found at the site suggest that the construction may have taken place between 40 and 60 A.D. The aqueduct supplied Nimes with water and is nearly 30 miles (50 kilometres) long. The section over the river Gard has arches at three levels and is 900 feet (275 metres) long and 160 feet (49 metres) high. The top level contains a channel 6 feet (1.8 metres) high and 4 feet (1.2 metres) wide with a gradient of 0.4 per cent to carry the water. The bottom level carries a roadway. The three levels were built in dressed stone without mortar.

Some researchers have estimated that the Segovia aqueduct was started in the second half of the 1st Century A.D. and completed in the early years of the 2nd Century, during the reign of either Emperor Vespasian (69-79 A.D.) or Nerva (96-98 A.D.). Others have suggested it was started under Emperor Domitian (81-96 A.D.) and probably completed under Trajan (98-117 A.D.). The aqueduct brought water to Segovia from the Frio River 10 miles (16 km) away. Its maximum height is 93 ft 6 in (28.5 metres), including nearly 19 ft 8 in (6 metres) of foundations and it is constructed from 44 double arches, 75 single arches and another four single arches giving a total of 167 arches. The bridge section of the aqueduct is 2240 feet (683 meters) long and changes direction several times. Like the Pont du Gard, it was built from dressed stone without mortar.

Circa 60 A.D. Greek mathematician Hero of Alexandria conceived the idea of a reaction turbine though he didn't call it that. He called it an Aeolipile (Aeolus - Greek God of the Wind) (Pila Latin - Ball) or the Sphere of Aeolus. It was a hollow sphere containing a small amount of water, free to rotate between two pivot points. When heated over a flame the steam from the boiling water escaped through two tangential nozzles in jets which caused the sphere to rotate at high speed. (See Hero's Aeolipile).

Alternative designs show the water boiled in a separate chamber being fed through a hollow pipe into the sphere through one of the pivots.

It has been suggested that this device was used by priests to perform useful work such as opening temple doors and moving statues to impress gullible worshippers but no physical evidence remains and these ideas were never developed and the aeolipile remained as a toy.

See more about Reaction Turbines.

See more about Steam Engines


150 A.D. Some time between 150 A.D. and 160 A.D. Greek astronomer and mathematician Claudius Ptolemaeus, Ptolemy a Roman citizen of Alexandria, (not one of the Ptolomaic Kings) published the Almagest "The Great Book". In it he summarised the all known information about astronomy and the mathematics which supported the theories. For over a thousand years it was the accepted explanation of the workings of the Universe. Unfortunately it was based on a geocentric model with uniform circular motions of the sun and planets around the Earth. Where this ideal motion did not fit the observed movements, the anomalies were explained by the concept of equants with the planets moving in smaller epicyclic orbits superimposed on the major orbit. It was not until Copernicus came along 1400 years later that Ptolemy's theory was seriously challenged. The Almagest was however a major source of information about Greek trigonometry.

In a similar vein to the Almagest, Ptolemy also published Geographia which summarised all that was known at the time about the World's geography as well as the projections used to create more accurate maps.

200 Greek philosopher Claudius Galen from Pergamum, Asia Minor, physician to five Roman emperors and surgeon to the Roman gladiators, was the first of many to claim therapeutic powers of magnets and to use them in his treatments. Galen carried out controlled experiments to support his theories and was the first to conclude that mental actively occurred in the brain rather than the heart, as Aristotle had suggested. Like many ancient philosophers his authority was virtually undisputed for many years after his death, thus discouraging original investigation and hampering medical progress until the 16th century.

But see Vesalius.

400 Greek scholar Hypatia of Alexandria took up her position as head of the Platonist school at the great Library of Alexandria, (in the period between its third and its fourth and final sacking), where she taught mathematics, astronomy and philosophy. The first recorded woman in science, she is considered to be the inventor of the hydrometer, called the aerometer by the Greeks. Claims that she also invented the planar astrolabe are probably not true since there is evidence that the astrolabe dates from 200 years earlier, but her mathematician father Theon of Alexandria had written a treatise on the device and she no doubt lectured about its use for calculating the positions of the Sun, Moon and stars.

Hypatia still held pagan beliefs at a time when the influence of Christianity was beginning to grow and unfortunately her science teachings were equated with the promotion of paganism. In 415 she was attacked by a Christian mob who stripped her, dragged her through the streets, killed her and cut her to pieces with broken pottery. Judging from her appearance as depicted by Victorian artists, it's no surprise that the local monks were outraged. See Hypatia 1885 by Charles William Mitchell.

426 Electric and magnetic phenomena were investigated by St Augustine who is said to have been "thunderstruck" on witnessing a magnet lift a chain of rings. In his book "City of God" he uses the example of magnetic phenomena to defend the idea of miracles. Magnetism could not be explained but it manifestly existed, so miracles should not be dismissed just because they could not be explained.

619 In 1999, archaeologists at Nendrum on Mahee Island in Ireland investigating what they thought to be a stone tidal pond used for catching fish uncovered two stone built tidal mills with a millstones and paddle blades dating from 619 AD and 787 AD. Several tidal mills were built during the Roman occupation of England for grinding grain and corn. They operated by storing water behind a dam during high tide, and letting it out to power the mill after the tide had receded and were the forerunners of the modern schemes for capturing tidal energy.

645 Xuan Zhuang the great apostle of Chinese Buddhism returned to China from India with Buddhist images and more than 650 Sanskrit Buddhist scriptures which were reproduced in large quantities giving impetus to the refinement of traditional methods of printing using stencils and inked squeezes first used by the Egyptians. A pattern of rows of tiny dots was made in a sheet of paper which was pressed down on top of a blank sheet and ink was forced through the holes. Later stencils developed by the Chinese and Japanese used human hair or silk thread to tie delicate isolated parts into the general pattern but there was no fabric backing to hold the whole image together. The stencil image was printed using a large soft brush, which did not damage the delicate paper pattern or the fine ties. These printing techniques of composite inked squeezes and stencils foreshadowed modern silk screen printing which was not patented until 1907.

700 - 1100 Islamic Science During Roman times, the flame of Greek science was maintained by Arab scholars who translated Greek scientific works into Arabic. From 700 A.D. however, when most of Europe was still in the Dark Ages, scientific developments were carried forward on a broad front by the Muslim world with advances in astronomy, mathematics, physics, chemistry and medicine. Chemistry (Arabic Al Khimiya "pour together", "weld") was indeed the invention of the Muslims who carried out pioneering work over three centuries putting chemistry to practical uses in the refinement of metals, dyeing, glass making and medicine. In those days the notion of alchemy also included what we would today call chemistry. Among the many notable muslim scientists from this period were Jabir Ibn Haiyan, Al-Khawarizmi and Al-Razi.

By the tenth century however, according to historian Toby Huff, the preeminence of Islamic science began to wane. It had flourished in the previous three centuries while Muslims were in the minority in the Islamic regions however, starting in the tenth century, widespread conversion to Islam took place and as the influence of Islam increased, so the tolerance of alternative educational and professional institutions and the radical ideas of freethinkers decreased. They were dealt a further blow in 1485, thirty five years after the invention of the printing press, when the Ottoman Sultan Byazid II issued an order forbidding the printing of Arabic letters by machines. Arabic texts had to be translated into Latin for publication and this no doubt hampered both the spread of Islamic science and ideas as well as the influence of the outside world on the Islamic community. This prohibition of printing was strictly enforced by subsequent Ottoman rulers until 1728 when the first printing press was established in Istanbul but due to objections on religious grounds it closed down in 1742 and the first Koran was not printed in Istanbul until 1875. Meanwhile in 1734 Deacon Abdalla Zakhir of the Greek Catholic Maronite Monastery of Saint John Sabigh in the Lebanon managed to establish the first independent Arabic printing press.

Islam was not alone in banning the dissemination of subversive or inconvenient ideas. Henry VIII in 1529, aware of the power of the press, became the first monarch to publish a list of banned books though he did not go so far as banning printing. He was later joined by others. In 1632 Galileo's book "Dialogue Concerning the Two Chief World Systems", in which he asserted that the earth revolved around the sun rather than the other way round, was placed by Pope Urban VIII on the index of banned books and Galileo was placed under house arrest. Despite these setbacks, European scientific institutions overcame the challenges by the church, taking over the flame carried by the Arabs and the sixteenth and seventeenth centuries became the age of Scientific Revolution in Europe.

776 Persian chemist Abu Musa Jabir Ibn Haiyan (721-815), also known as Geber, was the first to put chemistry on a scientific footing, laying great emphasis on the importance of formal experimentation. In the period around 776 A.D. he perfected the techniques of crystallisation, distillation, calcination, sublimation and evaporation and developed several instruments including the alembic (Arabic al-ambiq, "still") which simplified the process of distillation, for carrying them out. He isolated or prepared several chemical compounds for the first time, notably nitric, hydrochloric, citric and tartaric acids and published a series of books describing his work which were used as classic works on alchemy until the fourteenth century. Unfortunately the books were added to, under Geber's name, by various translators in the intervening period leading to some confusion about the extent of Geber's original work.

830 Around the year 830, Baghdad born mathematician Mohammad Bin Musa Al-Khawarizmi (770-840) published "The Compendium Book on Calculation by Completion and Balancing" in which he introduced the principles of algebra (Arabic Al-jabr "the reduction" i.e. of complicated relationships to a simpler language of symbols) which he developed for solving linear and quadratic equations. He also introduced the decimal system of Hindu-Arabic numerals to Europe as well as the concept of zero, a mathematical device at the time unknown in Europe used to Roman numerals. Al-Khawarizmi also constructed trigonometric tables for calculating the sine functions. The word algorithm (algorizm) is named after him.

850 Historian of Chinese inventions, Joseph Needham, identified 850 as the date of the first appearance of what the Chinese called the "fire chemical" or what we would now call gunpowder. Around that year, a book attributed to Chinese alchemist Cheng Yin warns of the dangerous incendiary nature of mixtures containing saltpetre (potassium nitrate), and sulphur, both essential components of gunpowder. Such chemicals mixed with various other substances including carbonaceous materials and arsenic had been used in various concentrations by alchemists since around 300 A.D. when Ko Hung proposed these mixtures in recipes for transforming lead into gold and mercury into silver while others later used them in attempts to create a potion of immortality.

After Cheng Yin's warning, similar mixtures were soon developed to produce flares and fireworks as well as military ordnance including burning bombs and fuses to ignite flame throwers burning petrol (gasoline). The first example of a primitive gun called a "fire arrow" appeared in 905, and in 994, arrows tipped with burning "fire chemicals" were used to besiege the city of Tzu-t'ung.

Most of these military applications were merely incendiary devices rather than explosives since they did not yet contain enough saltpetre (75%) to detonate. It was not until 1040 that the full power of the saltpetre rich mixture was discovered and the first true formula for gunpowder was published by Tseng Kung-Liang. After that, true explosive devices were developed including cannon and hand grenades and land mines.

Around 1150 it was realised that an arrow could be made to fly without the need for a bow by attaching to the shaft, a bamboo tube packed with a burning gunpowder mix. This led to the development of the rocket which was born when larger projectiles were constructed from the bamboo sticks alone without the arrows. A text from around that time describes how the combustion efficiency and hence the rocket thrust could be improved by creating a cavity in the propellant along the centre line of the rocket tube to maximise the burning surface - a technique still used in solid fuelled rockets today.

In 1221 Chinese chronicler Chao Yu-Jung recorded the first use of bombs which we would recognise today, with cast iron casings packed with explosives, which created deadly flying shrapnel when they exploded. They were used to great effect by a special catapult unit in Genghis Khan's Mongol army and by the Chinese Jin forces to defeat their Song enemies in the 1226 seige of Kaifeng.

920 Around the year 920, Persian chemist Mohammad Ibn Zakariya Al-Razi (865-925), known in the West as Rhazes, carried on Geber's work and prepared sulphuric acid, the "work horse" of modern chemistry and a vital component in the world's most common battery. He also prepared ethanol, which was used for medicinal applications, and described how to prepare alkali (Al-Qali, the salt work ashes, potash) from oak ashes. Al-Razi published his work on alchemy in his "Book of Secrets". The precise amounts of the substances he specified in his recipes demonstrates an understanding of what we would now call stoichiometry.

Several more words for chemicals are derived from their Arabic roots including alcohol (Al Kuhl" "essence", usually referring to ethanol) as well as arsenic and borax.


1040 Thermoremanent magnetisation described in the Wu Ching Tsung Yao "Compendium of Military Technology" in China. Compass needles were made by heating a thin piece of iron, often in the shape of a fish, to a temperature above the Curie Point then cooling it in line with the earth's magnetic field.

1041 Between 1041 and 1048 Chinese craftsman Pi Sheng produced the first printing press to use moveable type. Although his designs achieved widespread use in China, it was another four hundred years before the printing press was "invented" by Johann Gutenberg in Europe.

See more about Chinese Inventions.

1086 During the Song Dynasty (960-1127), Chinese astronomer, cartographer and mathematician Shen Kuo, in his Dream Pool Essays, describes the compass and its use for navigation and cartography as well as China's petroleum extraction and Pi Sheng's printing technique.

See more about Chinese Inventions.

1190 The magnetic compass "invented" in Europe 1400 years after the Chinese. Described for the first time in the west by a St Albans monk Alexander Neckam in his treatise De Naturis Rerum.

1250's Italian theologian St Thomas Aquinas stands up for the cause of "reason" reconciling the philosophy of Aristotle with Christian doctrine. Challenging Aristotle now became a challenge to the Church.

See also the Scientific Revolution

1269 Petrus Peregrinus de Marincourt, (Peter the Pilgrim) a French Crusader, used a compass to map the magnetic field of a lodestone. He discovered that a magnet had two magnetic poles, North and South and was the first to describe the phenomena of attraction and repulsion. He also speculated that these forces could be harnessed in a machine.

1285 The earliest record of a mechanical clock with an escapement or timing control mechanism is a reference to a payment to a clock keeper at (the original) St. Paul's in London. The invention of the verge and foliot escapement was an important breakthrough in measuring the passage of time allowing the development of mechanical timepieces.

The name verge comes from the Latin virga, meaning stick or rod. (See picture and explanation of the Verge Escapement)

The inventor of the verge escapement is not known but we know that it dates from 13th century Europe, where it was first used in large tower clocks which were built in town squares and cathedrals. The earliest recorded description of an escapement is in Richard of Wallingford's 1327 manuscript Tractatus Horologii Astronomici on the clock he built at the Abbey of St. Albans. It was not a verge, but a more complex variation.

For over 200 years the verge was the only escapement used in mechanical clocks until alternative escapements started to appear in the 16th century and it was 350 years before the more accurate pendulum clock was invented by Huygens.

1368-1644 China's Ming dynasty. When the Ming dynasty came into power, China was the most advanced nation on earth. During the Dark Ages in Europe, China had already developed cast iron, the compass, gunpowder, rockets, paper, paper money, canals and locks, block printing and moveable type, porcelain, pasta and many other inventions centuries before they were "invented" by the Europeans. From the first century B.C. they had also been using deep drilling to extract petroleum from the underlying rocks. They were so far ahead of Europe that when Marco Polo described these wondrous inventions in 1295 on his return to Venice from China he was branded a liar. China's innovation was based on practical inventions founded on empirical studies, but their inventiveness seems to have deserted them during the Ming dynasty and subsequently during the Qing (Ching) dynasty (1644 - 1911). China never developed a theoretical science base and both the Western scientific and industrial revolutions passed China by. Why should this be?

It is said that the answer lies in Chinese culture, to some extent Confucianism but particularly Daoism (Taoism) whose teachings promoted harmony with nature whereas Western aspirations were the control of nature. However these conditions existed before the Ming when China's innovation led the world. A more likely explanation can be found in China's imperial political system in which a massive society was rigidly controlled by all-powerful emperors through a relatively small cadre of professional administrators (Mandarins) whose qualifications were narrowly based on their knowledge of Confucian ideals. If the emperor was interested in something, it happened, if he wasn't, it didn't happen.

The turning point in China's technological dominance came when the Ming emperor Xuande came to power in 1426. Admiral Zheng He, a muslim eunuch, castrated as a boy when the Chinese conquered his tribe, had recently completed an audacious voyage of exploration on behalf of a previous Ming emperor Yongle to assert China's control of all of the known world and to extract tributary from its intended subjects. But his new master considered the benefits did not justify the huge expense of Zheng's fleet of 62 enormous nine masted junks and 225 smaller supply ships with their 27,000 crew. The emperor mothballed the fleet and henceforth forbade the construction of any ships with more than two masts, curbing China's aspirations as a maritime power and putting an end to its expansionist goals, a xenophobic policy which has lasted until modern times.

The result was that during both the Ming and the Qing dynasties a succession of complacent, conservative emperors cocooned in prodigious, obscene wealth, remote even from their own subjects, lived in complete isolation and ignorance of the rest of the world. Foreign influences, new ideas, and an independent merchant class who sponsored them, threatened their power and were consequently suppressed. By contrast the West was populated by smaller, diverse and independent nations competing with each other. Merchant classes were encouraged and innovation flourished as each struggled to gain competitive or military advantage.

Times have changed. Currently China is producing two million graduates per year, sixty percent of which are in science and technology subjects, three times as many as in the USA.

After Japan, China is the second largest battery producer in the world and growing fast.

1450 German goldsmith and calligrapher Johann Genstleisch zum Gutenberg from Mainz invented the printing press, considered to be one of the most important inventions in human history. For the first time knowledge and ideas could be recorded and disseminated to a much wider public than had previously been possible using hand written texts and its use spread rapidly throughout Europe. Intellectual life was no longer the exclusive domain of the church and the court and an era of enlightenment was ushered in with science, literature, religious and political texts becoming available to the masses who in turn had the facility to publish their own views challenging the status quo. It was the ability to publish and spread one's ideas that enabled the Scientific Revolution to happen. Nowadays the Internet is bringing about a similar revolution.

Although it was new to Europe, the Chinese had already invented printing with moveable type four hundred years earlier but, because of China's isolation, these developments never reached Europe.

Gutenberg printed Bibles and supported himself by printing indulgences, slips of paper sold by the Catholic Church to secure remission of the temporal punishments in Purgatory for sins committed in this life. He was a poor businessman and made little money from his printing system and depended on subsidies from the Archbishop of Mainz. Because he spent what little money he had on alcohol, the Archbishop arranged for him to be paid in food and lodging, instead of cash. Gutenberg died penniless in 1468.

1474 The first patent law, a statute issued by the Republic of Venice, provided for the grant of exclusive rights for limited periods to the makers of inventions. It was a law designed more to protect the economy of the state than the rights of the inventor since, as the result of its declining naval power, Venice was changing its focus from trading to manufacturing. The Republic required to be informed of all new and inventive devices, once they had been put into practice, so that they could take action against potential infringers.

1478 After 10 years working as an apprentice and assistant to successful Florentine artist Andrea del Verrocchio at the court of Lorenzo de Medici in Florence, at the age of 26 Leonardo da Vinci left the studio and began to accept commissions on his own.

One of the most brilliant minds of the Italian Renaissance, Leonardo was hugely talented as an artist and sculptor but also immensely creative as an engineer, scientist and inventor. The fame of his surviving paintings has meant that he has been regarded primarily as an artist, but his scientific insights were far ahead of their time. He investigated anatomy, geology, botany, hydraulics, optics, mathematics, meteorology, and mechanics and his inventions included military machines, flying machines, and numerous hydraulic and mechanical devices.

He lived in an age of political in-fighting and intrigue between the independent Italian states of Rome, Milan, Florence, Venice and Naples as well as lesser players Genoa, Siena, and Mantua ever threatening to degenerate into all out war, in addition to threats of invasion from France. In those turbulent times da Vinci produced a series of drawings depicting possible weapons of war during his first two years as an independent. Thus began a lifelong fascination with military machines and mechanical devices which became an important part of his expanding portfolio and the basis for many of his offers to potential patrons, the heads of these belligerent, or fearful, independent states.

Despite his continuing interest in war machines, he claimed he was not a war monger and he recorded several times in his notebooks his discomfort with designing killing machines. Nevertheless, he actively solicited such commissions because by then he had his own pupils and needed the money to pay them.

Most of Leonardo's designs were not constructed in his lifetime and we only know about them through the many models he made but mostly from the 13,000 pages of notes and diagrams he made in which he recorded his scientific observations and sketched ideas for future paintings, architecture, and inventions. Unlike academics today who rush into publication, he never published any of his scientific works, fearing that others would steal his ideas. Patent law was still in its infancy and difficult, if not impossible, to enforce. Such was his paranoia about plagiarism that he even wrote all of his notes, back to front, in mirror writing, sometimes also in code, so he could keep his ideas private. He was not however concerned about keeping the notes secret after his death and in his will he left all his manuscripts, drawings, instruments and tools to his loyal pupil, Francesco Melzi with no objection to their publication. Melzi expected to catalogue and publish all of Leonardo's works but he was overwhelmed by the task, even with the help of two full-time scribes, and left only one incomplete volume, "Trattato della Pintura" or "Treatise on Painting", about Leonardo's paintings before he himself died in 1570. On his death the notes were inherited by his son Orazio who had no particular interest in the works and eventually sections of the notes were sold off piecemeal to treasure seekers and private collectors who were interested more in Leonardo's art rather than his science.

Because of his secrecy, his contemporaries knew nothing of his scientific works which consequently had no influence on the scientific revolution which was just beginning to stir. It was about two centuries before the public and the scientific community began gradually to get access to Leonardo's scientific notes when some collectors belatedly allowed them to be published or when they ended up on public display in museums where they became the inspiration for generations of inventors. Unfortunately, only 7000 pages are known to survive and over 6000 pages of these priceless notebooks have been lost forever. Who knows what wisdom they may have contained?

Leonardo da Vinci is now remembered as both "Leonardo the Artist" and "Leonardo the Scientist" but perhaps "Leonardo the Inventor" would be more apt as we shall see below.

Leonardo the Artist

It would not do justice to Leonardo to mention only his scientific achievements without mentioning his talent as a painter. His true genius was not as a scientist or an artist, but as a combination of the two: an "artist-engineer".

He did not sign his paintings and only 24 of his paintings are known to exist plus a further 6 paintings whose authentication is disputed. He did however make hundreds of drawings most of which were contained in his copious notes.

  • The "Treatise on Painting"
  • This was the volume of Leonardo's manuscripts transcribed and compiled by Melzi. The engravings needed for reproducing Leonardo's original drawings were made by another famous painter, Nicolas Poussin. As the title suggests it was intended as technical manual for artists however it does contain some scientific notes about light, shade and optics in so far as they affect art and painting. For the same reason it also contains a small section of Leonardo's scientific works about anatomy. The publication of this volume in 1651 was the first time examples of the contents of Leonardo's notebooks were revealed to the world but it was 132 years after his death. The full range of his "known" scientific work was only made public little by little many years later.

Leonardo was one of the world's greatest artists, the few paintings he made were unsurpassed and his draughtsmanship had a photographic quality. Just seven examples of his well known artworks are mentioned here.

  • Paintings
    • The "Adoration of the Magi" painted in 1481.
    • The "Virgin of the Rocks" painted in 1483.
    • "The Last Supper" a large mural 29 feet long by 15 feet high (8.8 m x 4.6 m) started in 1495 which took him three years to complete.
    • The "Mona Lisa" (La Gioconda) painted in 1503.
    • "John the Baptist" painted in 1515.
  • Drawings
    • The "Vitruvian Man" as described by the Roman architect Vitruvius was drawn in 1490, showing the correlation between the proportions of the ideal human body with geometry, linking art and science in a single work.
    • Illustrations for mathematician Fra Luca Pacioli's book "De divina proportione" (The Divine Proportion), drawn in 1496. See more about The Divine Proportion.

Leonardo the Scientist

The following are some examples of the extraordinary breadth of da Vinci's scientific works

  • Military Machines
  • After serving his apprenticeship with Verrocchio, Leonardo had a continuous flow of military commissions throughout his working life.

    In 1481 he wrote to Ludovico Sforza, Duke of Milan with a detailed C. V. of his military engineering skills, offering his services as military engineer, architect and sculptor and was appointed by him the following year. In 1502 the ruthless and murderous Cesare Borgia, illegitimate son of Pope Alexander VI and seducer of his own younger sister (Lucrezia Borgia), appointed Leonardo as military engineer to his court where he became friends with Niccolo Machiavelli, Borgia's influential advisor. In 1507 some time after France had invaded and occupied Milan he accepted the post of painter and engineer to King Louis XII of France in Milan and finally in 1517 he moved to France at the invitation of King Francoise I to take up the post of First Painter, Engineer and Architect of the King. These commissions gave Leonardo ample scope to develop his interest in military machines.

    Leonardo designed war machines for both offensive and defensive use. They were designed to provide mobility and flexibility on the battlefield which he believed was crucial to victory. He also designed machines to use gunpowder which was still in its infancy in the fifteenth century.

    His military inventions included:

    • Mobile bridges including drawbridges and a swing bridge for crossing moats, ditches and rivers. His swing bridge was a cantilever design with a pivot on the river bank a counterweight to facilitate manoeuvring the span over the river. It also had wheels and a rope-and-pulley system which enabled easy transport and quick deployment.
    • Siege machines for storming walls.
    • Chariots with scythes mounted on the sides to cut down enemy troops.
    • A giant crossbow intended to fire large explosive projectiles several hundred yards.
    • Trebuchets - Very large catapults, based on releasing mechanical counterweights, for flinging heavy projectiles into enemy fortifications.
    • Bombards - Short barrelled, large-calibre, muzzle-loading, heavy siege cannon or mortars, fired by gunpowder and used for throwing heavy stone balls. The modern replacement for the trebuchet. Leonardo's design had adjustable elevation. He also envisaged exploding cannonballs, made up from several smaller stone cannonballs sewn into spherical leather sacks and designed to injure and kill many enemies at one time. We would now call these cluster bombs.
    • Springalds - Smaller, more versatile cannon, for throwing stones or Greek fire, with variable azimuth and elevation adjustment so that they could be aimed more precisely.
    • A series of guns and cannons with multiple barrels. The forerunners of machine guns.
    • They included a triple barrelled cannon and an eight barrelled gun with eight muskets mounted side by side as well as a 33 barrelled version with three banks of eleven muskets designed to enable one set of eleven guns to be fired while a second set cooled off and a third set was being reloaded. The banks were arranged in the form of a triangle with a shaft passing through the middle so that the banks could be rotated to bring the loaded set to the top where it could be fired again.

    • A four wheeled armoured tank with a heavy protective cover reinforced with metal plates similar to a turtle or tortoise shell with 36 large fixed cannons protruding from underneath. Inside a crew of eight men operating cranks geared to the wheels would drive the tank into battle. The drawing in Leonardo's notebook contains a curious flaw since the gearing would cause the front wheels to move in the opposite direction from the rear wheels. If the tank was built as drawn, it would have been unable to move. It is possible that this simple error would have escaped Leonardo's inventive mind but it is also suggested that like his coded notes, it was a deliberate fault introduced to confuse potential plagiarists. The idea that this armoured tank loaded with 36 heavy cannons in such a confined space could be both operated and manoeuvred by eight men is questionable.
    • Automatic igniting device for firearms.
  • Marine Warfare Machines and Devices
  • Leonardo also designed machines for naval warfare including:

    • Designs for a peddle driven paddle boat. The forerunner of the modern pedalo.
    • Hand flippers and floats for walking on water.
    • Diving suit to enable enemy vessels to be attacked from beneath the water's surface by divers cutting holes below the boat's water line. It consisted of a leather diving suit equipped with a bag-like helmet fitting over the diver's head. Air was supplied to the diver by means of two cane tubes attached to the headgear which led up to a cork diving bell floating on the surface.
    • A double hulled ship which could survive the exterior skin being pierced by ramming or underwater attack, a safety feature which was eventually adopted in the nineteenth century.
    • An armoured battleship similar to the armoured tank which could ram and sink enemy ships.
    • Barrage cannon - a large floating circular platform with 16 canons mounted around its periphery. It was powered and steered by two operators turning drive wheels geared to a large central drive wheel connected to paddles for propelling it through the water. Others operators fired the cannons.
  • Flying Machines
  • Leonardo studied the flight of birds and after the legendary Icarus was one of the first to attempt to design human powered flying machines, recording his ideas in numerous drawings. A step up from Chinese kites.

    His drawings included:

    • A design for a parachute. The world's first.
    • Various gliders
    • Designs for wings intended to carry a man aloft, similar to scaled up bat wings.
    • Human powered mechanisms for flapping wings by means of levers and cables.
    • An ornithopter or helical air screw with its central shaft powered by a circular human treadmill intended to lift off and fly like a modern helicopter.
  • Civil Works
  • Leonardo designed many civil works for his patrons and also the equipment to carry them out.

    These included:

    • A crane for excavating canals, a dredger and lock gates designed with swinging gates rather than the lifting doors of the "portcullis" or "guillotine" designs which were typically used at the time. Leonardo's gates also contained smaller hatches to control the rate of filling the lock to avoid swamping the boats.
    • Water lifting devices based on the Archimedes screw and on water wheels
    • Water wheels for powering mechanical devices and machines.
    • Architecture: Leonardo made many designs for buildings, particularly cathedrals and military structures, but none of them were ever built.
    • When Milan, with a population of 200,000 living in crowded conditions, was beset by bubonic plague Leonardo set about designing an a more healthy and pleasant ideal city. It was to be built on two levels with the upper level reserved for the householders with living quarters for servants and facilities for deliveries on the lower level. The lower level would also be served by covered carriageways and canals for drainage and to carry away sewage while the residents of the upper layer would live in more tranquil, airy conditions above all this with pedestrian walkways and gardens connecting their buildings.
    • Leonardo produced a precision map of Imola, accurate to a few feet (about 1 m) based on measurements made with two variants of an odometer or what we would call today a surveyor's wheel which he designed and which he called a cyclometer. They were wheelbarrow-like carts with geared mechanisms on the axles to count the revolutions of the wheels from which the distance could be determined. He followed up with physical maps of other regions in Italy.
  • Tools and Instruments
  • The following are examples of some of the tools and scientific instruments designed by da Vinci which were found in his notes.

    • Solar Heating - In 1515 when he worked at the Vatican, Leonardo designed a system of harnessing solar energy using a large concave mirror, constructed from several smaller mirrors soldered together, to focus the Sun's rays to heat water.
    • Improvements to the printing press to simplify its operation so that it could be operated by a single worker.
    • Anemometer - It consisted of a horizontal bar from which was suspended a rectangular piece of wood by means of a hinge. The horizontal bar was mounted on two curved supports on which a scale to measure the rotation of the suspended wood was marked. When the wind blew, the wood swung on its hinge within the frame and the extent of the rotation was noted on the scale which gave an indication of the force of the wind.
    • A 13 digit decimal counting machine - Based on a gear train and often incorrectly identified as a mechanical calculator.
    • Clock - Leonardo was one of the early users of springs rather than weights to drive the clock and to incorporate the fusée mechanism, a cone-shaped pulley with a helical groove around it which compensated for the diminishing force from the spring as it unwound. His design had two separate mechanisms, one for minutes and one for hours as well as an indication of phases of the moon.
    • He also designed numerous machines to facilitate manufacturing including a water powered mechanical saw, horizontal and vertical drilling machines, spring making machines, machines for grinding convex lenses, machines for grinding concave mirrors, file cutting machines, textile finishing machines, a device for making sequins, rope making machines, lifting hoists, gears, cranks and ball bearings.
    • Though drawings and models exist, the claim that Leonardo invented the bicycle is thought by many to be a hoax. The rigid frame had no steering mechanism and it is impossible to ride.
  • Theatrical Designs
    • Leonardo was often in demand for designing theatrical sets and decorations for carnivals and court weddings.
    • He also built automata in the form of robots or animated beasts whose lifelike movements were created by a series of springs, wires, cables and pulleys.
    • His self propelled cart, powered by a spring, was used to amaze theatre audiences.
    • He designed musical instruments including a lyre, a mechanical drum, and a viola organista with a keyboard. This latter instrument consisted of a series of strings each tuned to a different pitch. A bow in the form of a continuously rotating loop perpendicular to the strings was stretched between two pulleys mounted in front of the strings. The keys on the keyboard were each associated with a particular string and when a key was pressed a mechanism pushed the bow against the corresponding string to play the note.
  • Anatomy
  • As part of his training in Veroccio's studio, like any artist, Leonardo studied anatomy as an aid to figure drawing, however starting around 1487 and later with the doctor Marcantonio della Torre he made much more in depth studies of the body, its organs and how they function.

    • During his studies Leonardo had access to 30 corpses which he dissected, removing their skin, unravelling intestines and making over 200 accurate drawings their organs and body parts.
    • He made similar studies of other animals, dissecting cows, birds, monkeys, bears, and frogs, and comparing their anatomical structure with that of humans.
    • He also observed and tried to comprehend the workings of the cardiovascular, respiratory, digestive, reproductive and nervous systems and the brain without much success. He did however witness the killing of a pig during a visit to an abattoir. He noticed that when a skewer was thrust into its heart, that the beat of the heart coincided with the movement of blood into the main arteries. He understood the mechanism of the heart if not the function, predating by over 100 years, the conclusions of Harvey about its function.

    Because the bulk of his work was not published for over 200 years, his observations could possibly have prompted an earlier advance in medical science had they been made available during his lifetime. At least his drawings provided a useful resource for future students of anatomy.

  • Scientific Writings
  • Leonardo had an insatiable curiosity about both nature and science and made extensive observations which were recorded in his notebooks.

    They included:

    • Anatomy, biology, botany, hydraulics, mechanics, ballistics, optics, acoustics, geology, fossils

    He did not however develop any new scientific theories or laws. Instead he used the knowledge gained from his observations to improve his skills as an artist and to invent a constant stream of useful machines and devices.

"Leonardo the Inventor"

Leonardo unquestionably had one of the greatest inventive minds of all time, but very few of his designs were ever constructed at the time. The reason normally given is that the technology didn't exist during his lifetime. With his skilled draughtsmanship, Leonardo's designs looked great on paper but in reality many of them would not actually work in practice, an essential criterion for any successful invention, and this has since been borne out by subsequent attempts to construct the devices as described in his plans. This should not however detract in any way from Leonardo's reputation as an inventor. His innovations were way ahead of their time, unique, wide ranging and based on sound engineering principles. What was missing was the science.

At least he had the benefits of Archimedes' knowledge of levers, pulleys and gears, all of which he used extensively, but that was the limit of available science.

Newton's Laws of Motion were not published until two centuries after Leonardo was working on his designs. The science of strength of materials was also unheard of until Newton's time when Hooke made some initial observations about stress and strain and there was certainly no data available to Leonardo about the engineering properties of materials such as tensile, compressive, bending and impact strength or air pressure and the densities of the air and other materials. Torricelli's studies on air pressure came about fifty years before Newton, and Bernoulli's theory of fluid flow, which describe the science behind aerodynamic lift, did not come till fifty 50 years after Newton. But, even if the science had existed, Leonardo lacked the mathematical skills to make the best of it.

So it's not surprising that Leonardo had to make a lot of assumptions. This did not so much affect the function of his mechanisms nor the operating principle on which they were based, rather it affected the scale and proportions of the components and the force or power needed to operate them. His armoured tank would have been immensely heavy and difficult to manoeuvre, and it's naval version would have sunk unless its buoyancy was improved. The wooden gears used would probably have been unable to transmit the enormous forces required to move these heavy vehicles. The repeated recoil forces on his multiple-barrelled guns may have shattered their mounts, and his flying machines were very flimsy with inadequate area of the wings as well as the level of human power needed to keep them aloft. So there was nothing fundamentally wrong with most of his designs and most of the shortcomings could have been overcome with iterative development and testing programmes to refine the designs. Unfortunately Leonardo never had that opportunity.

"Leonardo the Myths"

Leonardo was indeed a genius but his reputation has also been enhanced or distorted by uncritical praise. Speculation, rather than firm evidence, about the performance of some of the mechanisms mentioned in his notebooks and what may have been in the notebooks which have been lost, has incorrectly credited him with the invention of the telescope, mathematical calculating machines and the odometer to name just three examples.

Though he did experiment with optics and made drawings of lenses, he never mentioned in his notes, a telescope, or what he may have seen with it, so it is highly unlikely that he invented the telescope.

As for his so called calculating machine: It looked very similar to the calculator made by Pascal 150 years later but it was in fact just a counting machine since it did not have an accumulator to facilitate calculations by holding two numbers at a time in the machine as in Pascal's calculator.

Leonardo's "telescope" and "calculating machine" are examples of uninformed speculation from tantalising sketches made, without corresponding explanations, in his notes. Such speculation is based on the reasoning that, if one of his sketches or drawings "looks like" some more recent device or mechanism, then it "must be" or actually "is" an early example of such a device. Leonardo already had a well deserved reputation as a genius without this unnecessary gold plating.

Similarly regarding the odometer: The claim by some, though not by Leonardo himself, that he invented the odometer implies that he was the first to envisage the concept of an odometer. The odometer was in fact invented by Vitruvius 15 centuries earlier. Leonardo invented "an" odometer, not "the" odometer. Many inventions are simply improvements, alternatives or variations, of what went before. Without a knowledge of precedents, it is a mistake to extrapolate a specific case to a general conclusion. Leonardo's design was based on measuring the rotation of gear wheels, whereas Vitruvius' design was based on counting tokens. (Note that Vitruvius also mentions in his "Ten Books on Architecture", designs for trebuchets, water wheels and battering rams protected by mobile siege sheds or armoured vehicles which were called "tortoises".)

It is rare to find an invention which depends completely on a unique new concept and many perfectly good inventions are improvements or alternatives to prior art. This applies to some of Leonardo's inventions just as it does to the majority of inventions today. Nobody would (or should) claim that Leonardo invented the clock when his innovation was to incorporate a new mechanical movement into his own version of a clock, nor should they denigrate his actual invention.

It's a great pity that Leonardo kept his works secret and that they remained unseen for so many years after his death. How might technology have advanced if he had been willing to share his ideas, to explain them to his contemporaries and to benefit from their comments?

1492 Discovery of the New World by Christopher Columbus showed that the Earth still held vast unknowns indirectly giving impetus to the scientific revolution.

1499 The first patent for an invention was granted by King Henry VI to Flemish-born John of Utynam for a method of making stained glass, required for the windows of Eton College giving John a 20-year monopoly. The Crown thus started making specific grants of privilege to favoured manufacturers and traders, signified by Letters Patent, open letters marked with the King's Great Seal.

The system was open to corruption and in 1623 the Statute of Monopolies was enacted to curb these abuses. It was a fundamental change to patent law which took away the rights of the Crown to create trading monopolies and guaranteed the inventor the legal right of patents instead of depending on the royal prerogative. So called patent law, or more generally intellectual property law, has undergone many changes since then to encompass new concepts such as copyrights and trademarks and is still evolving as and new technologies such as software and genetics demand new rules.

1500 to 1700 The Scientific Revolution and The Age of Reason

Up to the end of the sixteenth century there had been little change in the accepted scientific wisdom inherited from the Greeks and Romans. Indeed it had even been reinforced in the thirteenth century by St. Thomas Aquinas who proclaimed the unity of Aristotelian philosophy with the teachings of the church. The credibility of new scientific ideas was judged against the ancient authority of Aristotle, Galen, Ptolemy and others whose science was based on rational thought which was considered to be superior to experimentation and empirical methods. Challenging these conventional ideas was considered to be a challenge to the church and scientific progress was hampered accordingly.

In medieval times, the great mass of the population had no access to formal education let alone scientific knowledge. Their view of science could be summed up in the words of Arthur C. Clarke, "Any sufficiently advanced technology is indistinguishable from magic".

Things began to change after 1500 when a few pioneering scientists discovered, and were able to prove, flaws in this ancient wisdom. Once this happened others began to question accepted scientific theories and devised experiments to validate their ideas. In the past, such challenges had been hampered by the lack of accurate measuring instruments which had limited the range of experiments that could be undertaken and it was only in the seventeenth century that instruments such as microscopes, telescopes, clocks with minute hands, accurate weighing equipment, thermometers and manometers started to become available. Experimenters were then able to develop new and more accurate measurement tools to run their experiments and to explore new scientific territories thus accelerating the growth of new scientific knowledge.

The printing press was the great catalyst in this process. Scientists could publish their work, thus reaching a much greater audience, but just as important, it gave others working in the field, access to the latest developments. It gave them the inspiration to explore these new scientific domains from a new perspective without having to go over ground already covered by others.

The increasing use of gunpowder also had its effect. Cannons and hand held weapons swept the aristocratic knight from the field of battle. Military advantage and power went to those with the most effective weapons and heads of state began to sponsor experimentation in order to gain that advantage.

Scientific method thus replaced rational thought as a basis for developing new scientific theories and over the next 200 years scientific theories and scientific institutions were transformed, laying the foundations on which the later Industrial Revolution depended.

Some pioneers are shown below.

  • (600 B.C.) Thales The original thinker, deprecated by Aristotle.
  • (1450) Johannes Gutenberg did not make any scientific breakthroughs but his printing press was one of the most important developments and essential prerequisites which made the scientific revolution possible. For the first time it became easy to record information and to disseminate knowledge making learning and scholarship available to the masses.
  • (1492) Christopher Columbus' discovery of the New World showed that the World still held vast unknowns sparking curiosity
  • (1514) Nicolaus Copernicus challenged the accepted wisdom that the Earth was the centre of the universe and proposed instead that the universe was centred on the Sun.
  • (1543) Andreas Vesalius showed that conventional wisdom about human anatomy was incorrect.
  • (1576) Tycho Brahe made detailed astronomical measurements to enable predictions of planetary motion to be based on observations rather than logical deduction.
  • (1600) William Gilbert an early advocate of scientific method rather than rational thought.
  • (1605) Francis Bacon like Gilbert, a proponent of scientific method.
  • (1608) Hans Lippershey invented the telescope, thus providing the tools for much more accurate observations, and deeper understanding of the cosmos.
  • (1609) Johannes Kepler developed mathematical relationships, based on Brahe's measurements which enabled planetary movements to be predicted.
  • (1610) Galileo Galilei demonstrated that the Earth was not the centre of the Universe and in so doing, brought himself into serious conflict with the church.
  • (1628) William Harvey outlined the true function of the heart correcting misconceptions about the functions and flow of blood as well as classical myths about its purpose.
  • (1642) Pascal together with Fermat described chance and probability in mathematical terms, rather than fate or the will of the Gods.
  • (1643) Evangelista Torricelli's invention of the barometer led to an understanding of the properties of air.
  • (1644) René Descartes challenged Aristotle's logic based on rational thinking with his own mathematical logic and attempted to describe the whole universe in mathematical terms. He was still not convinced of the value of experimental method.
  • (1656) Christiaan Huygens invented the pendulum clock enabling scientific experiments to be supported by accurate time measurements for the first time.
  • (1660) The Royal Society was founded in London to encourage scientific discovery and experiment.
  • (1661) Robert Boyle introduced the concept of chemical elements based on empirical observations rather than Aristotle's logical earth, fire, water and air.
  • (1663) Otto von Guericke devised an experiment using his Magdeburg Spheres to disprove Aristotle's claim that a vacuum can not exist.
  • (1665) Robert Hooke invented the microscope which opened a window on the previously unseen microscopic world raising questions about life itself.
  • (1666) The French Académie des Sciences was founded in Paris.
  • (1668) Antonie van Leeuwenhoek expanded on Hooke's observations and established microbiology.
  • (1687) Isaac Newton derived a set of mathematical laws which provided the basis of a comprehensive understanding of the physical world.
  • (1700) The German Academy of Sciences was founded in Berlin.

The Age of Reason marked the triumph of evidence over dogma. Or did it? There remained one great mystery yet to be unravelled but it was another 200 years before it came up for serious consideration: The Origin of Species.

1514 Polish polymath and Catholic cleric, Nicolaus Copernicus mathematician, economist, physician, linguist, jurist, and accomplished statesman with astronomy as a hobby published and circulated to a small circle of friends, a preliminary draft manuscript in which he described his revolutionary idea of the heliocentric universe in which celestial bodies moved in circular motions around the Sun, challenging the notion of the geocentric universe. Such heresies were unthinkable at the time. They not only contradicted conventional wisdom that the World was the centre of the universe but worse still they undermined the story of creation, one of the fundamental beliefs of the Christian religion. Dangerous stuff!

It was not until around 1532 that Copernicus completed the work which he called De Revolutionibus Orbium Coelestium "On the Revolutions of the Heavenly Spheres" but he still declined to publish it. Historians do not agree on whether this was because Copernicus was unsure that his observations and his calculations would be sufficiently robust enough to challenge Ptolemy's Almagest which had survived almost 1400 years of scrutiny or whether he feared the wrath of the church. Copernicus' model however was simpler than Ptolemy's geocentric model and matched more closely the observed motions of the planets. He eventually agreed to publish the work at the end of his life and the first printed copy was reportedly delivered to him on his deathbed, at the age of seventy, in 1543.

As it turned out, "De Revolutionibus Orbium Coelestium" was put on the Catholic church's index of prohibited books in 1616, as a result of Galileo's support for its revolutionary theory, and remained there until 1835.

One of the most important books ever written, De Revolutionibus' ideas ignited the Scientific Revolution (See above), but only about 300 or 400 were printed and it became known (recently) as "the book that nobody read".

1543 Belgian physician and professor at the University of Padua, Andries van Wesel, more commonly known as Vesalius published De Humani Corporis Fabrica (On the Structure of the Human Body), one of the most influential books on human anatomy. He carried out his research on the corpses of executed criminals and discovered that the research and conclusions published by the previous, undisputed authority on this subject, Galen, could not possibly have been based on an actual human body. Versalius was one of the first to rely on direct observations and scientific method rather than rational logic as practiced by the ancient philosophers and in so doing overturned 1300 years of conventional wisdom. Such challenges to long held theories marked the start of the Scientific Revolution.

1551 Damascus born Muslim polymath, Taqi al-Din, working in Egypt, described an impulse turbine used to drive a rotating spit over a fire. It was simply a jet of steam impinging on the blades of a paddle wheel mounted on the end of the spit. Like Hero's reaction turbine it was not developed at the time for use in more useful applications.

See more about Impulse Turbines.

See more about Steam Engines


1576 Danish astronomer and alchemist, Tycho Brahe, built an observatory where, with his assistant Johannes Kepler, he gathered data with the aim of constructing a set of tables for calculating the position of the planets for any date in the past or in the future. He lived before the invention of the telescope and his measurements were made with a cross staff, a simple mechanical device used for measuring angles. Nevertheless, despite his primitive instruments, he set new standards for precise and objective measurements but he still relied on empirical observations rather than mathematics for his predictions.

Brahe accepted Copernicus' heliocentric model for the orbits of planets which explained the apparent anomalies in their orbits exhibited by Ptolemy's geocentric model, however he still clung on to the Ptolemaic model for the orbits of the Sun and Moon revolving around the Earth as this fitted nicely with the notion of Heaven and Earth and did not cause any conflicts with religious beliefs.

However, using the data gathered together with Brahe, Kepler was able to confirm the heliocentric model for the orbits of planets, including the Earth, and to derive mathematical laws for their movements.

See also the Scientific Revolution

A wealthy, hot-headed and extroverted nobleman, said to own one percent of the entire wealth of Denmark, Brahe had a lust for life and food. He wore a gold prosthesis in place of his nose which it was claimed had been cut off by his cousin in a duel over who was the better mathematician.

In 1601, Brahe died in great pain in mysterious circumstances, eleven days after becoming ill during a banquet. Until recently the accepted explanation of the cause of death, provided by Kepler, was that it was an infection arising from a strained bladder, or from rupture of the bladder, resulting from staying too long at the dining table.

By examining Brahe's remains in 1993, Danish toxicologist Bent Kaempe determined that Brahe had died from acute Mercury poisoning which would have exhibited similar symptoms. Among the many suspects, in 2004 the finger was firmly pointed by writers Joshua and Anne-Lee Gilder, at Kepler, the frail, introverted son of a poor German family.

Kepler had the motive, he was consumed by jealousy of Brahe and he wanted his data which could make him famous but it had been denied to him. He also had the means and the opportunity. After Tycho's death when his family were distracted by grief, Kepler simply walked away with the priceless observations which belonged to Tycho's heirs.

With only a few tantalising facts to go on, historians attempt to construct a more complete picture of what happened in the distant past. In Brahe's case there could be another explanation of his demise. From the available facts it could be concluded the Brahe's death was due to an accidental overdose of Mercury, which at the time was the conventional medication prescribed for the treatment for syphilis, or from syphilis itself. This is corroborated by the fact that one of the symptoms of the advanced state of the disease is the loss of the nose due to the collapse of the bridge tissue. Brahe's hedonistic lifestyle could well have made this a possibility. Kepler's actions in purloining of Brahe's data could have been a simple act of opportunism rather than the motivation for murder.

1593 The thermometer invented by Italian astronomer and physicist Galileo Galilei. It has been variously called an air thermometer or a water thermometer but it was called a thermoscope at the time. His "thermometer" consisted of a glass bulb at the end of a long glass tube held vertically with the open end immersed in a vessel of water. As the temperature changed the water would rise or fall in the tube due to the contraction or expansion of the air. It was sensitive to air pressure and could only be used to indicate temperature changes since it had no scale. In 1612 Italian Santorio Santorio added a scale to the apparatus creating the first true thermometer and for the first time, temperatures could be quantified.

There is no evidence that the decorative, so called, Galileo thermometers based on the Archimedes principle were invented by Galileo or that he ever saw one. They are comprised of several sealed glass floats in a sealed liquid filled glass cylinder. The density of the liquid varies with the temperature and the floats are designed with different densities so as to float or sink at different temperatures. There were however thriving glass blowing and thermometer crafts based in Florence (Tuscany) where the Academia del Cimento, which was noted for its instrument making, produced many of these thermometers also known as Florentine thermometers or Infingardi (Lazy-Ones) or Termometros Lentos (Slow) because of the slowness of the motion of the small floating spheres in the alcohol of the vial. It is quite likely that these designs were the work of the Grand Duke of Tuscany Ferdinand II who had a special interest in thermometers and meteorology.

1600 William Gilbert of Colchester, physician to Queen Elizabeth I of England published "De Magnete" (On the Magnet) the first ever work of experimental physics. In it he distinguished for the first time static electric forces from magnetic forces. He discovered that the earth is a giant magnet just like one of the stones of Peregrinus, explaining how compasses work. He is credited with coining the word "electric" which comes from the Greek word "elektron" meaning amber.

Many wondrous powers have been ascribed to magnets and to this day magnetic bracelets are believed by some to have therapeutic benefits. In Gilbert's time it was believed that an adulteress could be identified by placing a magnet under her pillow. This would cause her to scream or be thrown out of bed as she slept.

Gilbert proved amongst other things that the smell of garlic did not affect a ship's compass. It is not known whether he experimented with adulteresses in his bed.

Gilbert was the English champion of the experimental method of scientific discovery considered inferior to rational thought by the Greek philosopher Aristotle and his followers. He held the Copernican or heliocentric view, dangerous at the time, that the Sun, not the Earth was not the centre of the universe. He was a contemporary of the Italian astronomer Galileo Galilei (1564-1642) who made a principled stand in defence of the founding of physics on scientific method and precise measurements rather than on metaphysical principles and formal logic. These views brought Galileo into serious confrontation with the church and he was tried and punished for his heresies.

Experimental method rather than rational thought was the principle behind the Scientific Revolution which separated Science (theories which can be proved) from Philosophy (theories which can not be proved).

Gilbert died of Bubonic plague in 1603 leaving his books, globes, instruments and minerals to the College of Physicians but they were destroyed in 1666 in the great fire of London which mercifully also brought the plague to an end.

1603 Italian shoemaker and part-time alchemist from Bologna, Vincenzo Cascariolo, searching for the "Philosopher's Stone" for turning common metals into Gold discovered phosphorescence instead. He heated a mixture of powdered coal and heavy spar (Barium sulphate) and spread it over an iron bar. It did not turn into Gold when it cooled, as expected, but he was astonished to see it glow in the dark. Though the glow faded it could be "reanimated" by exposing it to the sun and so became known as "lapis solaris" or "sun stone", a primitive method of solar energy storage in chemical form.

1605 A five digit encryption code consisting only of the letters "a" and "b" giving 32 combinations to represent the letters of the alphabet was devised by English philosopher and lawyer Francis Bacon. He called it a biliteral code. It is directly equivalent to the five bit binary Baudot code of ones and zeros used for over 100 years for transmitting data in twentieth century telegraphic communications.

More importantly Bacon, together with Gilbert, was an early champion of scientific method although it is not known whether they ever met.

Bacon criticized the notion that scientific advances should be made through rational deduction. He advocated the discovery of new knowledge through scientific experimentation. Phenomena would be observed and hypotheses made based on the observations. Tests would then be conducted to verify the hypotheses. If the tests produced reproducible results then conclusions could be made.

In his 1605 publication "The Advancement of Learning", Bacon coined the dictum "If a man will begin with certainties, he will end up with doubts; but if he will be content to begin with doubts, he shall end up in certainties"

See also the Scientific Revolution

Bacon died as a result of one of his experiments. He investigated preserving meat by stuffing a chicken with snow. The experiment was a success but Bacon died of bronchitis contracted either from the cold chicken or from the damp bed, reserved for VIP's and unused for a year, where he was sent to recover from his chill.

There are many "Baconians" who claim today that at least some of Shakespeare's plays were actually written by Bacon. One of the many arguments put forward is that only Bacon possessed the necessary wide range of knowledge and erudition displayed in Shakespeare's plays.

1608 German born spectacle lens maker Hans Lippershey working in Holland, applied for a patent for the telescope for which he envisioned military applications. The patent was not granted on the basis that "too many people already have knowledge of this invention". Nevertheless, Lippershey's patent application was the first documented evidence of such a device. Legend has it that the telescope was discovered by accident when Lippershey, or two children playing with lenses in his shop, noticed that the image of a distant church tower became much clearer when viewed through two lenses, one in front of the other. The discovery revolutionised astronomy. Up to that date the pioneering work of Copernicus, Brahe and Kepler had all been based on many thousands of painstaking observations made with the naked eye without the advantage of a telescope.

See also the Scientific Revolution

1609 On the death of Danish Imperial Mathematician Tycho Brahe in 1601, German Mathematician Johannes Kepler inherited his position along with the astronomical data that Brahe had gathered over many years of pains-taking observations. From this mass of data on planetary movements, collected without the help of a telescope, Kepler derived three Laws of Planetary Motion, the first two published as "Astronomia Nova" in 1609 and the third as "Harmonices Mundi" in 1619. These laws are:

  • The Law of Orbits: All planets move in elliptical orbits, with the Sun at one focus.
  • The Law of Areas: A line that connects a planet to the Sun sweeps out equal areas in equal times. See Diagram
  • The Law of Periods: The square of the period of any planet is proportional to the cube of the semi major axis of its orbit.

Kepler's laws were the first to enable accurate predictions of future planetary orbits and at the same time they effectively disproved the Aristotelian and Ptolemaic model of geocentric planetary motion. Further evidence was provided during the same period by Galileo (See following entry).

Kepler derived these laws empirically from the years of data gathered by Brahe, a monumental task, but he was unable to explain the underlying principles involved. The answer was eventually provided by Newton.

Recently Kepler's brilliance has been tarnished by forensic studies which suggest that he murdered Brahe in order to get his hands on his observations. (See Brahe)

See also the Scientific Revolution

1610 Italian physicist and astronomer Galileo Galilei was the first to observe the heavens through a refracting telescope. Using a telescope he had built himself, based on what he had heard about Lippershey's recent invention, he observed four moons, which had not previously been visible with the naked eye, orbiting the planet Jupiter. This was revolutionary news since it was definitive proof that the Earth was not the centre of all celestial movements in the universe, overturning the geocentric or Ptolemaic model of the universe which for more than a thousand years had been the bedrock of religious and Aristotelian scientific thought. At the same time his observations of mountains on the Earth's moon contradicted Aristotelian theory, which held that heavenly bodies were perfectly smooth spheres.

Publication of these observations in his treatise Sidereus Nuncius (Starry Messenger) gave fresh impetus to the Scientific Revolution in astronomy started by the publication of Copernicus' heliocentric theory almost 100 years before, but brought Galileo into a confrontation with the church. Charged with heresy, Galileo was made to kneel before the inquisitor and confess that the heliocentric theory was false. He was found guilty and sentenced to house arrest for the rest of his life.

Galileo carried out many investigations and experiments to determine the laws governing mechanical movement. He is famously reputed to have demonstrated that all bodies fall to earth at the same rate, regardless of their mass by dropping different sized balls from the top of the Leaning Tower of Pisa, thus disproving Aristotle's theory that the speed of falling bodies is directly proportional to their weight but there is no evidence that Galileo actually performed this experiment. However such an experiment was also performed by Simon Stevin in 1586.

In 1971, Apollo 15 astronaut David Scott repeated Galileo's experiment on the airless Moon with a feather and a hammer demonstrating that, unhampered by any atmosphere, they both fell to the ground at the same rate.

Galileo actually attempted to measure the rate at which a body falls to Earth under the influence of gravity, but he did not have an accurate method of measuring the time since the speed of the falling body was too fast and the duration too short. He therefore determined to "dilute" the effect of gravity by rolling a ball down an inclined plane to slow it down and increase the transit time. He expected to find that the distance travelled would increase by a fixed amount for each fixed increment in time. Instead he discovered that the distance travelled is proportional to the square of the time. See more about Galileo's "Laws of Motion"

His inquisitive mind led him to make a remarkable discovery about the motion of pendulums. While sitting in a cathedral he observed the swinging of a chandelier and using his pulse to determine the period of its swing, he was greatly surprised to find that as the movement of the pendulum slowed down, its period remained the same. His curiosity piqued he followed up with a series of experiments and determined that the only factor affecting the period of the pendulum's swing was its length. It was independent of the arc of the swing and the speed of the swing. By using pendulums of different length Galileo was able to produce timing devices which were much more accurate than his pulse.

About 40 years later, Christiaan Huygens developed a mathematical equation defining the period of the pendulum and went on to use the pendulum in the construction of the first accurate clocks.

1614 Scottish nobleman John Napier Baron of Merchiston, published Mirifici Logarithmorum Canonis Descriptio - Description of the Marvellous Canon (Rule) of Logarithms in which he described a new method for carrying out tedious multiplication and division by simpler addition and subtraction, together with a set of tables he had calculated for the purpose. The logarithmic tables contained 241 entries which had taken him 20 years to compute.

Napier's logarithms were not the logarithms we would recognise today. Neither were they Natural logarithms with a base of "e" as is often misquoted. Natural logarithms were invented by Euler over a century later.

Napier was aware that numbers in a geometric series could be multiplied by adding their exponents (powers) for example q2 multiplied by q3 = q5, and that division could be performed by subtracting the exponents. Simple though the idea of logarithms may be, it had not been considered before because with a simple base of 2 and exponent n, where n is a whole number, the numbers represented by 2n become very large very quickly as n increases. This meant there was no obvious way of representing the intervening numbers. The idea of fractional exponents would have, (and did eventually) solve this problem but at the end of the sixteenth century, people were just getting to grips with the notion of zero and they were not comfortable with idea of fractional powers.

To design a way of representing more numbers, while still retaining whole number exponents, Napier came up with the idea of making the base number smaller. But, if the base number was very small there would be too many numbers. Using the number 1 (unity) as a base would not work either since all the powers of 1 are equal to 1. He therefore chose (1-10-7) or 0.9999999 as the base from which he constructed his tables. Napier named his exponents logarithms from the Greek logos and arithmos roughly translated as ratio-number.

Napier's publication was an instant hit with astronomers and mathematicians. Among these was Henry Briggs, mathematics professor at Gresham College, London who travelled 350 miles to Edinburgh the following year to meet the inventor of this new mathematical tool.

He stayed a month with Napier and in discussions they considered two major improvements that they both readily accepted. Briggs suggested that the tables should be constructed from a base of 10 rather than (1-10-7) and this meant adopting fractional exponents and Napier agreed that the logarithm of 1 should be 0 (zero) rather than the logarithm of 107 being 0 as it was in his original tables. Briggs' reward was to have the job of calculating the new logarithmic tables which he eventually completed and published as Arithmetica Logarithmica in 1624. His tables contained 30,000 natural numbers to 14 places.

Meanwhile in 1617 Napier published a description of a new invention in his Rabdologiae, a "collection of rods". It was a practical method of multiplication using "numbering rods" with numbers marked off on them. Known as Napier's Bones", surprisingly they did not use his method of logarithms.(See also the following item - Gunter)

Already old and frail, Napier died the same year without seeing the final results of his work.

Briggs' logarithms are still in use today, now known as common logarithms.

Napier himself considered his greatest work to be a denunciation of the Roman Catholic Church which he published in 1593 as A Plaine Discovery of the Whole Revelation of St John.

1620 Edmund Gunter professor of astronomy at Gresham College, where Briggs was professor of mathematics, made a straight logarithmic scale engraved on a wooden rod and used it to perform multiplication and division using a set of dividers or calipers to add or subtract the logarithms. The predecessor to the slide rule. (See the following item)

1621 English mathematician and clergyman, William Oughtred, friend of Briggs and Gunter from Gresham College, put two of Gunter's scales (See previous item) side by side enabling logarithms to be added directly and invented the slide rule, the essential tool of every engineer for the next 350 years until electronic calculators were invented in the 1970s.

Oughtred also produced a circular version of the slide rule.

1628 English physician Robert Harvey published "De Motu Cordis" ("On the Motion of the Heart and Blood") in which he was the first to describe the circulation of blood and how it is pumped around the body by the heart, dispelling any remaining Aristotelian beliefs that the heart was the seat of intelligence and the brain was a cooling mechanism for the blood.

See also the Scientific Revolution

1629 Italian Jesuit priest Nicolo Cabeo published Philosophia Magnetica in which electric repulsion is identified for the first time.

1642 At the age of eighteen, French mathematician and physicist, Blaise Pascal constructed a mechanical calculator capable of addition and subtraction. Known as the Pascaline, it was the forerunner of computing machines. Despite its utility, this great innovation failed to capture the imagination (or the attention) of the scientific and commercial public and only fifty were made. Thirty years later it was eclipsed by Leibniz' four function calculator which could perform multiplication and division as well as addition and subtraction.

Pascal also did pioneering work on hydraulics, resulting in the statement of Pascal's principle, that "pressure will be transmitted equally throughout a confined fluid at rest, regardless of where the pressure is applied". He explained how this principle could be used to exert very high forces in a hydraulic press. Such a system would have two cylinders with pistons with different cross-sectional areas connected to a common reservoir or simply connected by a pipe. When a force is exerted on the smaller piston, it creates a pressure in the reservoir proportional to the area of the piston. This same pressure also acts on the larger piston, but because its area is greater, the pressure is translated into a larger force on the larger piston. The difference in the two forces is proportional to the difference in area of the two pistons and the hydraulic, mechanical advantage is equal to the ratio of the areas of the two pistons. Thus the cylinders act in a similar way to a lever, as described by Archimedes, which effectively magnifies the force exerted. 150 years later Bramah was granted a patent for inventing the hydraulic press.

The unit of pressure was recently named the "Pascal" in his honour, replacing the older, more descriptive, pounds per square inch (psi) or Newtons per square metre (N/M2).

Besides hydraulics, Pascal explained the concept of a vacuum. At the time, the conventional Aristotelian view was that the space must be full with some invisible matter and a vacuum was considered an impossibility.

In 1653 Pascal described a convenient shortcut for determining the coefficients of a binomial series, now called Pascal's Triangle and the following year, in response to a request from a gambling friend, he used it to derive a method of calculating the odds of particular outcomes of games of chance. In this case, two players wishing to finish a game early, wanted to divide their remaining stakes fairly depending on their chances of winning from that point. To arrive at a solution, he corresponded with fellow mathematician Fermat and together they worked out the notion of expected values and laid the foundations of the mathematical theory of probabilities.

See Pascal's Triangle and Pascal Probability

Pascal did not claim to have invented his eponymous triangle. It was known to Persian mathematicians in the eleventh and twelfth centuries and to Chinese mathematicians in the eleventh and thirteenth centuries as well as others in Europe and was often named after local mathematicians.

For most of his life Pascal suffered from poor health and he died at the age of 39 after abandoning science and devoting most of the last ten years of his short life to religious studies culminating in the publication (posthumously) of Pensées (Thoughts), a justification of the Christian faith.

See also the Scientific Revolution

1643 Evangelista Torricelli served as Galileo's secretary and succeeded him as court mathematician to Grand Duke Ferdinand II and in 1643 made the world's first barometer for measuring atmospheric or air pressure by balancing the pressure force, due to the weight of the atmosphere, against the weight of a column of mercury. This was a major step in the understanding of the properties of air.

1644 French philosopher and mathematician René Descartes published Principia Philosophiae in which he attempts to put the whole universe on a mathematical foundation reducing the study to one of mechanics. Considered to be the first of the modern school of mathematics, he believed that Aristotle's logic was an unsatisfactory means of acquiring knowledge and that only mathematics provided the truth so that all reason must be based on mathematics.

He was still not convinced of the value of experimental method considering his own mathematical logic to be superior.

His most important work La Géométrie, published in 1637, includes his application of algebra to geometry from which we now have Cartesian geometry.

See also the Scientific Revolution

Descartes accepted sponsorship by Queen Christina of Sweden who persuaded him to go to Stockholm. Her daily routine started at 5.00 a.m. whereas Descartes was used to rising at at 11 o'clock. After only a few months in the cold northern climate, walking to the palace for 5 o'clock every morning, he died of pneumonia.

1646 The word Electricity coined by English physician Robert Browne even though he contributed nothing else to the science.


1651 German chemist Johann Rudolf Glauber in his "Practise on Philosophical Furnaces" describes a safety valve for use on chemical retorts. It consisted of a conical valve with a lead cap which would lift in response to excessive pressure in the retort allowing vapour to escape and the pressure to fall. The weight of the cap would reseat the valve once the pressure returned to an acceptable level. Today, modern implementations of Glauber's valve are the basis of the pressure vents incorporated into sealed batteries to prevent rupture of the cells due to pressure build up.

In 1658 Glauber published Opera Omnia Chymica "Complete Works of Chemistry", a description of different techniques for use in chemistry which was widely reprinted.

1654 The first sealed liquid-in-glass thermometer produced by the artisan Mariani at the Academia del Cimento in Florence for the Grand Duke of Tuscany, Ferdinand II. It used alcohol as the expanding liquid but was inaccurate in absolute terms, although his thermometers agreed with each other, and there was no standardised scale in use.

1656 Building on Galileo's discoveries, Dutch physicist and astronomer Christiaan Huygens determined that the period P of a pendulum is given by:

P = 2 π √(l/g)

Where l is the length of the pendulum and g is the acceleration due to gravity.

Huygens made the first practical pendulum clock making accurate time measurement possible for the first time. Previous mechanical clocks had pointers which indicated the progress of slowly rising water or slowly falling weights and were only accurate to large fractions of an hour. Huygens clock enabled time to be measured in seconds. It depended on gearing a mechanical indicator to the constant periodic motion of a pendulum. Falling weights transferred just enough energy to the pendulum to overcome friction and air resistance so that it did not stop.

The pendulum clock remained the world's most accurate time-keeper for nearly 300 years until the invention of the quartz clock in 1927.

Huygens also made many astronomical observations noting the characteristics of Saturn's rings and the surface of Mars. He was also the first to make a reasoned estimate of the distance of the stars. He assumed that Sirius had the same brightness as the Sun and from a comparison of the light intensity received here on Earth he calculated the distance to Sirius to be 2.5 trillion miles. It is actually about 20 times further away than this. There was however nothing wrong with Huygens' calculations. It was the assumption which was incorrect. Sirius is actually much brighter than the Sun, but he had no way of knowing that. Had he know the true brightness of Sirius, his estimation would have been much closer to the currently accepted value.

1658 Irish Archbishop James Ussher, following a literal interpretation of the bible, calculated that the Earth was created on the evening of 22 October 4004 B.C.

1660 English mathematician and astronomer, Richard Towneley together with his friend, physician Henry Power investigated the the expansion of air at different altitudes by enclosing a fixed mass of air in a Torricelli/Huygens U-tube with its open end immersed in a dish of mercury. They noted the expansion of the enclosed air at different altitudes on a hill near their home and concluded that gas pressure, the external atmospheric pressure of the air on the mercury, was inversely proportional to the volume. They communicated their findings to Robert Boyle a distinguished contemporary chemist who verified the results and published them two years later as Boyle's Law. Boyle referred to Towneley's conclusions as "Towneley's Hypothesis".

1660 The Royal Society founded in London as a "College for the Promoting of Physico-Mathematical Experimental Learning", which met weekly to discuss science and run experiments. Original members included chemist Robert Boyle and architect Christopher Wren.

See also the Scientific Revolution

1661 Huygens invents the U tube manometer, a modification of Torricelli's barometer, for determining gas pressure differences. In a typical "U Tube" manometer the difference in pressure (really a difference in force) between the ends of the tube is balanced against the weight of a column of liquid. The gauges are only suitable for measuring low pressures, most gauges recording the difference between the fluid pressure and the local atmospheric pressure when one end of the tube is open to the atmosphere.

1661 Irish chemist Robert Boyle published "The Sceptical Chymist" in which he introduced the concept of elements. At the time only 12 elements had been identified. These included nine metals, Gold, Silver, Copper, Tin, Lead, Zinc, Iron, Antimony and Mercury and two non metals Carbon and Sulphur all of which had been known since antiquity as well as Bismuth which had been discovered in Germany around 1400 A. D.. Platinum had been known to South American Indians from ancient times but only became to the attention of Europeans in the eighteenth century. Boyle himself discovered phosphorus which he extracted from urine in 1680 taking the total of known elements to fourteen.

Though an alchemist himself, believing in the possibility of transmutation of metals, he was one of the first to break with the alchemist's tradition of secrecy and published the details of his experimental work including failed experiments.

See also the Scientific Revolution

1662 Boyle published Boyle's Law stating that the pressure and volume of a gas are inversely proportional.

PV=K The first of the Gas Laws.

The relationship was originally discovered in 1660 by English mathematician Richard Towneley but attributed to Boyle. Both Towneley and Boyle were not aware that the relationship was temperature dependent and it was not until 1676 that the relationship was rediscovered by French physicist and priest, Abbé Edme Mariotte, and shown to apply only when the gas temperature is held constant. The law is known as Mariotte's Law in non-English speaking countries.

1663 Otto von Guericke the Burgomaster of Magdeburg in Germany invented the first electric generator, which produced static electricity by rubbing a pad against a large rotating sulphur ball which was turned by a hand crank. It was essentially a mechanised version of Thales demonstrations of electrostatics using amber in 600 B.C. and the first machine to produce an electric spark. Von Guericke had no idea what the sparks were and their production by the machine was regarded at the time as magic or a clever trick. The device enabled experiments with electricity to be carried out but since it was not until 1729 that the possibility of electric conduction was discovered by Gray, the charged sulphur ball had to be moved to the place where the electric experiment took place. Von Guericke's generator remained the standard way of producing electricity for over a century.

Von Guericke was famed more for his studies of the properties of a vacuum and for his design of the Magdeburg Hemispheres experiment. In 1650, in a challenge to Aristotle's theory that a vacuum can not exist, like many of Aristotle's theories, accepted uncritically by philosophers as conventional wisdom for centuries and encapsulated in the saying "Nature abhors a vacuum", von Guericke set about disproving this theory by experimental means. In 1650 he designed a piston based air pump with which he could evacuate the air from a chamber and he used it to create a vacuum in experiments which showed that sound of a bell in a vacuum can not be heard, nor can a vacuum support a candle flame or animal life. To demonstrate the strength of a vacuum, in 1654 he constructed two hollow copper hemispheres which fitted together along a greased flange forming a hollow sphere. When the air was evacuated from the sphere, the external air pressure held the hemispheres together and two teams of horses could not pull them apart, yet when air was released into the sphere the hemispheres simply fell apart.

(See Magdeburg Hemispheres picture).

See also the Scientific Revolution

1665Boyle published a description of a hydrometer for measuring the density of liquids which was essentially the same as those still in use today for measuring the specific gravity (S.G.) of the electrolyte in Lead Acid batteries. Hydrometers consist of a sealed capsule of lead or mercury inside a glass tube into which the liquid being measured is placed. The height at which the capsule floats represents the density of the liquid.

The hydrometer is however considered to be the invention of Greek mathematician Hypatia.

1665 English polymath, Robert Hooke published Micrographia in which he illustrated a series of very small insects and plant specimens he had observed through a microscope he had constructed himself for the purpose. It included a description of the eye of a fly and tiny sections of plant materials for which he coined the term "cells" because their distinctive walls reminded him of monk's or prison quarters. The publication also included the first description of an optical microscope, and it is claimed, was the inspiration to Antonie van Leeuwenhoek who is often credited himself with the invention of the microscope. Hooke's publication was the first major publication of the recently founded Royal Society and was the first scientific best-seller, inspiring a wide public interest in the new science of microscopy.

See also the Scientific Revolution

1666 The French Académie des Sciences was founded in Paris by King Louis XIV at the instigation of Jean-Baptiste Colbert the French Minister of Finances, as a government organisation with the aim of encouraging and protecting French scientific research. Colbert's dirigiste economic policies were protectionist in nature and involved the government in regulating French trade and industry, echoes of which remain to this day.

1668 Dutch draper, haberdasher and scientist, Antonie Phillips van Leeuwenhoek, possibly inspired by Hooke's Micrographia (see above) made his first microscope. Known as the "Father of Microbiology" he subsequently produced over 450 high quality lenses and 247 microscopes which he used to investigate biological specimens. He was the first to observe and describe single-celled organisms and was also the first to observe and record muscle fibers, bacteria, spermatozoa, and blood flow in capillaries. Van Leeuwenhoek kept the British Royal Society informed of the results of his extensive investigations and eventually became a member himself.

1675Boyle discovered that electric force could be transmitted through a vacuum and observed attraction and repulsion.

1676 Prolific English engineer, surveyor, architect, physicist, inventor, socialite and self publicist, Robert Hooke, considered by some to be England's Leonardo (there were others - see Cayley), is now mostly remembered for for Hooke's Law for springs which states that the extension of a spring is proportional to the force applied, or as he wrote it in Latin "Ut tensio, sic vis" ("as is the extension, so is the force"). From this the energy stored in the spring can be calculated by integrating the force times the displacement over the extension of the spring. The force per unit extension is known as the spring constant. Hooke actually discovered his law in 1660, but afraid that he would be scooped by his rival Newton, he published his preliminary ideas as an anagram "ceiiinosssttuv" in order to register his claim for priority. It was not until 1676 that he revealed the law itself. The forerunner of digital time stamping?

Hooke was surveyor of the City of London and assistant to Christopher Wren in rebuilding the city after the great fire of 1666. He made valuable contributions to optics, microscopy, astronomy, the design of clocks, the theories of springs and gases, the classification of fossils, meteorology, navigation, music, mechanical theory and inventions, but despite his many achievements he was overshadowed by his contemporary Newton with whom he was unfortunately, constantly in dispute. Hooke claimed a role in some of Newton's discoveries but he was never able to back up his theories with mathematical proofs. Apparently there was at least one subject which he had not mastered.

1673 Between the years 1673 and 1686, German mathematician, diplomat and philosopher, Gottfried Wilhelm Leibniz, developed his theories of mathematical calculus publishing the first account of differential calculus in 1684 followed by the explanation of integral calculus in 1686. Unknown to him these techniques were also being developed independently by Newton. Newton got there first but Leibniz published first and arguments about priority raged for many years afterwards. Leibniz's notation has been adopted in preference to Newton's but the concepts are the same.

He also introduced the words function, variable, constant, parameter and coordinates to explain his techniques.

Leibniz was a polymath and another candidate for the title "The last man to know everything". As a child he learned Latin at the age of 8, Greek at 14 and in the same year he entered the University of Leipzig where he earned a Bachelors degree in philosophy at the age of 16, a Bachelors degree in law at 17 and Masters degrees in both philosophy and law at the age of 20. At 21 he obtained a Doctorate in law at Altdorf. In 1672 when he was 26, his diplomatic travels took him to Paris where he met Christiaan Huygens who introduced him to the mathematics of the pendulum and inspired him to study mathematics more seriously.

In 1679 Leibniz proposed the concept of binary arithmetic in a letter written to French mathematician and Jesuit missionary to China, Joachim Bouvet, showing that any number may be expressed by 0's and 1's only. Now the basis of digital logic and signal processing used in computers and communications.

Surprisingly Leibniz also suggested that God may be represented by unity, and "nothing" by zero, and that God created everything from nothing. He was convinced that the logic of Christianity would help to convert the Chinese to the Christian faith. He believed that he had found an historical precedent for this view in the 64 hexagrams of the Chinese I Ching or the Book of Changes attributed to China's first shaman-king Fuxi (Fu Hsi) dating from around 2800 B.C. and first written down as the now lost manual Zhou Yi in 900 B.C.. A hexagram consists of blocks of six solid or broken lines (or stalks of the Yarrow plant) forming a total of 64 possibilities. The solid lines represent the bright, positive, strong, masculine Yang with active power while the broken or divided lines represent the dark, negative, weak, feminine Yin with passive power. According to the I Ching, the two energies or polarities of the Yin and Yang are both opposing and complementary to each other and represent all things in the universe which is a progression of contradicting dualities.

Although the I Ching had more to do with fortune telling than with mathematics, there were other precedents to Leibniz's work. The first known description of a binary numeral system was made by Indian mathematician Pingala variously dated between the 5th century B.C. or the 2nd century B. C..

In 1671 Leibniz invented a 4 function mechanical calculator which could perform addition, subtraction, multiplication and division on decimal numbers which he demonstrated to the Royal Society in London in 1673 but they were not impressed by his crude prototype machine. (Pascal's 1642 calculator could only perform addition and subtraction.) It was not until 1676 that Leibniz eventually perfected it. His machine used a stepped cylinder to bring into mesh different gear wheels corresponding to the position of units, tens, hundreds etc. to operate on the particular digit as required. Strangely, as the inventor of binary arithmetic, he did not use it in his calculator.

His most famous philosophical proposition was that God created "the best of all possible worlds".

1681 French physicist and inventor Denis Papin invented the pressure release valve or safety valve to prevent explosions in pressure vessels. Although Papin is credited with the invention, safety valves had in fact been described by Glauber thirty years earlier, however Papin's valve was adjustable for different pressures by means of moving the lead weight along a lever which kept the valve shut. Papin's safety valve became a standard feature on steam engines saving many lives from explosions

The invention of the safety valve came as a result of his work with pressurised steam. In 1679 he had invented the pressure cooker which he called the steam digester.

Observing that the steam tended to lift the lid of his cooker in 1690 Papin also conceived the idea of using the pressure of steam to do useful work. He introduced a small amount of water into a cylinder closed by a piston. On heating the water to produce steam, the pressure of the steam would force the piston up. Cooling the cylinder again caused the steam to condense creating a vacuum under the piston which would pull it down (In fact the atmospheric pressure would push the piston down). This pumping action by a piston in a cylinder was the genesis of the reciprocating steam engine. Papin envisaged two applications for his piston engine. One was a toothed rack attached to the piston whose movement turned a gear wheel to produce rotary motion. The other was to use the reciprocating movements of the piston to move oars or paddles in a steam powered boat. Unfortunately he was unable to attract sponsors to enable him to develop these ideas. Papin was not the first to use a piston, von Guericke came before him, but he was the first to use it to capture the power of steam to do work.

In 1707, with the collaboration of Gottfried Leibniz (still smarting over his dispute with Isaac Newton), Papin published " The New Art of Pumping Water by Using Steam". The Papin / Leibniz pump had many similarities to Savery's 1698 water pump and their claims resulted in a protracted dispute involving the British Royal Society as to the true inventor of the steam driven water pump. Savery's pump did not use a piston but used a vacuum to draw water from below the pump and steam pressure to discharge it at a higher level. Papin's pump on the other hand used only steam pressure and could not draw water from a lower level. (See diagram of Papin's Steam Engine)

Unlike Savery's pump, Papin's pump used a closed cylinder, adjacent to (or even partially immersed in) the lower pool, fed with water from the pool through a non-return valve at the bottom of the cylinder. In the cylinder a free piston rested on the surface of the water which, at it's highest point, was level with the water in the pool. Steam from a separate boiler introduced above the piston forced it downwards displacing the water in the cylinder through another non-return valve at the bottom of the cylinder and upwards to the discharge level. Simply by exhausting the steam from the cylinder through a tap, the external water pressure would cause the cylinder to refill with water through the non-return valve at the base of the cylinder elevating the piston once more to the level of the surrounding water pool. Cooling was unnecessary since the design did not depend on creating a vacuum in the cylinder.

Papin also suggested a way of using his pump to create rotary motion. He proposed to feed the water raised by the pump over a waterwheel returning it to a lower reservoir in a closed loop system.

Like many gifted inventors Papin died destitute.

See more about Steam Engines


1687 "Philosophiae Naturalis Principia Mathematica" - Mathematical Principles of Natural Philosophy published by English physicist and mathematician Isaac Newton. One of the most important and influential books ever published, it was written in Latin and not translated into English until 1729.

By coincidence Newton was born in 1642, the year that Galileo died.

He made significant advances in the study of Optics demonstrating in 1672 that white light is made up from the spectrum of colours observed in the rainbow. He used a prism to separate white light into its constituent colour spectrum and by means of a second prism he showed that the colours could be recombined into white light.

He is perhaps best remembered however for his Mechanics, the Laws of Motion and Gravitation which his "Principia" contains.

Newton's Laws of Motion can be summarised as follows:

  • First Law: - Any object will remain at rest or in uniform motion in a straight line unless compelled to change by some external force.
  • Second Law: - The acceleration a of a body is directly proportional to, and in the same direction as, the net force F acting on it, and inversely proportional to its mass m. Thus, F = ma.
  • Third law: - To every action there is an equal and opposite reaction.

70 years earlier, Galileo came very close to developing these relationships but he had neither the mathematical tools nor the instruments to make precise measurements to prove his theories. Newton's first law is a restatement of Galileo's concept of inertia or resistance to change which he measured by its mass. See a Comparison of Galileo's and Newton's "Laws of Motion"

Newton also developed the Law of Universal Gravitation which states that any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Thus:

F = G m1m2 / r2


F is force between the bodies

G is the Universal Gravitational Constant

m1 and m2 are the masses of the two bodies

r is the distance between the centres of the bodies

Newton was thus able to calculate or predict gravitational forces using the concept of action at a distance. He did not discover gravity nor could he explain it. Galileo was well aware of the effects of gravity, and so was Huygens, a contemporary of Newton, who believed Descartes' earlier theory that gravity could be explained in mechanical terms as a high speed vortex in the aether which caused tiny particles to be thrown outwards by the centrifugal force of the vortex while heavier particles fell inwards due to balancing centripetal forces. Huygens never accepted Newton's inverse square law of gravity.

Newton's concept that planetary motion was due to gravity was completely new. Before that, the motion of heavenly bodies had been explained by Gilbert as well as his contemporary the German astronomer Kepler (1571-1630), and others as being due to magnetic forces.

Even now in the twenty first century, will still do not have a satisfactory explanation of the nature of gravitational forces.

Newton was the giant of the Scientific Revolution. He assimilated the advances made before him in mathematics, astronomy, and physics to derive a comprehensive understanding of the physical world. The impact of the publication of Newton's laws of dynamics on the scientific community was both profound and wide ranging. The laws and Newton's methods provided the basis on which other theories, such as fluid dynamics, kinetic energy and work done were built and down to earth technical knowledge which enabled the building of the machines to power the Industrial Revolution and, at the other end of the spectrum, they explained the workings of the Universe.

However, of equal or even greater importance was the fact that Newton showed for the first time, the general principle that natural phenomena, events and time varying processes, not just mechanical motions, obey laws that can be represented by mathematical equations enabling analysis and predictions to be made. The laws of nature represented by the laws of mathematics, the foundation of modern science. The 3 volume publication was thus a major turning point in the development of scientific thought, sweeping away superstition and so called "rational deduction" as ways of explaining the wonders of nature.

Newton's reasoning was supported by his invention of the mathematical techniques of Differential and Integral Calculus and Differential Equations, actually developed in 1665 and 1666, twenty years before he wrote the "Principia" but not used in the proofs it contains. These were major advances in scientific knowledge and capability which extended the range of existing mathematical tools available for characterising nature and for carrying out scientific analysis.

Newton engaged in a prolonged feud with Robert Hooke who claimed priority on some of Newton's ideas. Newton's oft repeated quotation "If I have seen further, it is by standing on the shoulders of giants." was actually written in a sarcastic letter to Hooke, who was almost short enough to be classified as a dwarf, with the implication that Hooke didn't qualify as one of the giants.

Leibniz working contemporaneously with Newton also developed techniques of differential and integral calculus and a dispute developed with Newton as to who was the true originator. Newton's discovery was made first, but Leibniz published his work before Newton. However there is no doubt that both men came to the ideas independently. Newton developed his concept through a study of tangents to a curve and also considered variables changing with time, while Leibniz arrived at his conclusions from calculations of the areas under curves and thought of variables x, y as ranging over sequences of infinitely close values.

Newton is revered as the founder of modern physical science, but despite the great fame he achieved in his lifetime, he remained a modest, diffident, private and religious man of simple tastes. He never married, devoting his life to science.

Newton didn't always have his head in the clouds. In his spare time, when he wasn't dodging apples, he invented the cat-flap.

1698 Searching for a method of replacing the manual or animal labour for pumping out the seeping water which gathered at the bottom of coal mines, English army officer Thomas Savery designed a mechanical, or more correctly, a hydraulic water pump powered by steam. He called the process "Raising Water by Fire". Savery was impressed by the great power of atmospheric pressure working against a vacuum as demonstrated by von Guericke's Magdeburg Hemispheres experiment. He realised that a vacuum could be produced by condensing steam in a sealed chamber and he used this principle as the basis for the first practical steam driven water pump which became known as "The Miner's Friend". Savery's pump did not produce any mechanical motion but used atmospheric pressure to force the water up a vertical pipe from a well or pond below, to fill the vacuum in the steam chamber above, and steam pressure to drive the water in the steam chamber up a vertical discharge pipe to a level above the steam chamber.

(See diagram of Savery's Steam Engine)

The essential components of the pump were a boiler producing steam, a steam chamber at the heart of the system and suction and discharge water pipes each containing a non-return flap valve he called a clack.

Starting with some water in the steam chamber, the steam valve from the boiler is opened introducing steam into the steam chamber where the pressure of the steam forces the water out through a non-return flap valve into the the discharge pipe. The head of water in the discharge pipe keeps the flap valve closed so the water can not return into the steam chamber. The steam supply to the chamber is then turned off and the chamber is cooled from the outside with cold water which causes the steam in the chamber to condense creating a vacuum in the chamber. The vacuum in turn causes water to be sucked up from the well or lower pond through another flap valve in the induction pipe into the steam chamber. The head of water in the steam chamber keeps the flap valve closed so that the water can not flow back to the well. Once the chamber is full, steam is fed once more into the chamber and the cycle starts again.

Efficiency was improved by using two parallel steam chambers alternately such that one of the chambers was charged with steam while the other chamber was cooled. The theoretical maximum depth from which Savery's engine can draw water is limited by the atmospheric pressure which can support a head of 32 feet (10 M) but because of leaks the practical limit is about 25 feet. In a mine this would require the engine to be below ground close to the water level, but as we know, fire and coal mines don't mix. On the discharge side the maximum height to which the water can be raised is limited by the available steam pressure and also by the safety of the pressure vessels whose solder joints are particularly vulnerable, a serious drawback with the available 17th century technology.

See more about Steam Engines


1700 At the instigation of Leibniz, King Frederick I of Prussia founded the German Academy of Sciences in Berlin to rival Britain's Royal Society and the French Académie des Sciences. Leibniz was appointed as its first president

1701 English gentleman farmer Jethro Tull, developed the seed drill, a horse-drawn sowing device which mechanised the planting of seeds, precisely positioning them in the soil and then covering them over. It thus enabled better control of the distribution and positioning of the seeds leading to improvements of up to nine times in crop yields per acre (or hectare). For the farm hand, the seed drill cut out some of the back-breaking work previously employed in the task but the downside was that it also reduced the number of farm workers needed to plant the crop. The seed drill was a relatively simple device which could be made by local carpenters and blacksmiths. Its combined benefits of higher crop yields and productivity improvements were the first steps in mechanised farming which revolutionised British agriculture.

The design concept was not new since similar devices had been used in Europe in the middle ages. Single tube seed drills were also known to have been used in Sumeria in Mesopotamia, now (modern day Iraq) during the Late Bronze Age (1500 B.C.) and multi-tube drills were used in China during the Qin Dynasty.

The introduction of Tull's improved seed drill was an early example of the mechanisation of manual labour tasks which ushered in the Industrial Revolution in Britain.

1705 Head of demonstrations at the Royal Society in London, English physicist and instrument maker appointed by Isaac Newton, Francis Hauksbee the Elder demonstrated an electroluminescent glow discharge lamp which gave off enough light to read by. It was based on von Guericke's electric generator with an evacuated glass globe, containing mercury, replacing the sulphur ball. It produced a glow when he rubbed the spinning globe with his bare hands. The blue light it produced seemed to be alive and was considered at the time to be the work of God. Like von Guericke, Hauksbee never realised the potential of electricity. Instead, electric phenomena were for many years the tool of conjurors and magicians who entertained people at parties with mild electric shocks, producing sparks or miraculously picking up feathers.

1709 Abraham Darby, from a Quaker family in Bristol established an iron making business at Coalbrookdale in Shropshire introducing new production methods which revolutionised iron making. He already had a successful brass ware business in Bristol employing casting and metal forming technologies he had learned in the Netherlands and in 1708 he had patented the use of sand casting which he realised was suitable for the mass production of cheaper iron pots for which there was a ready market. The purpose of his move to Coalbrookdale which already had a long established iron making industry was to apply these technologies and his metallurgical knowledge to the iron making business to produce cast iron kettles, cooking pots, cauldrons, fire grates and other domestic ironware with intricate shapes and designs.

He experimented with using coal instead of charcoal but the high sulphur content of coal made the iron too brittle. His greatest breakthrough was the use of coke, replacing charcoal in the iron smelting process which reduced costs and improved the quality of the castings. This was partially out of necessity since the surrounding countryside had been denuded of trees to produce charcoal to fuel the local iron making blast furnaces, but there was still a plentiful local supply of coal as well as iron ore and limestone.

See the following Footnote about Iron and Steel Making.

Abraham Darby founded a dynasty of iron makers. His son, Abraham Darby II, expanded the output of the Coalbrookdale ironworks to include iron wheels and rails for horse drawn wagon ways and cylinders for the steam engines recently invented by Newcomen some of which he used himself to pump water supplying his water wheels. His grandson, Abraham Darby III, continued in the business and was the promoter responsible for building the world's first iron bridge at Coalbrookdale.

The mass production of low cost ironware made possible by Abraham Darby's iron making process was a major foundation stone on which the subsequent industrialisation of Britain and the Industrial Revolution were based.

  • Footnote
  • Iron and Steel Making

    The principle behind the iron making or smelting process is the chemical reduction of the iron ores which are composed of iron oxides, mainly FeO, Fe2O3, and Fe3O4 by heating them in a furnace, together with carbon where the carbon is converted to carbon monoxide (CO), which then acts as the reducing agent in the following typical reactions. The process itself is exothermic.

    2C + O2 → 2CO

    3CO + Fe2O3 → 2Fe + 3CO2

    Iron ore however contains a variety of unwanted impurities which affect the properties of the finished iron in different ways and so must be removed from the ore or at least controlled to an acceptable level.

    • Wrought Iron
    • Wrought iron was initially developed by the Hittites around 2000 B.C. In early times in Europe the smelting process was carried out by the village blacksmith in a bloomery using charcoal as the carbon source with the oxygen being provided by a bellows blowing air through a tuyère into the furnace. It was not usually possible with this method to achieve a temperatures as high as 1300°C, the melting point of iron, but it was sufficient to heat up the iron to a spongy mass called a bloom, separating it the from the majority of impurities in the iron ore but leaving some glassy silicates included in the iron. If the furnace temperature was allowed to get too high the bloom could melt and carbon could dissolve into the iron giving it the unwanted properties of cast iron.

      Once the reduction process is complete the bloom is removed from the furnace and by heating and hammering it, the impurities are forced out but some of the silicates remain as slag, which is mainly calcium silicate, CaSiO3, in fibrous inclusions in the iron creating wrought iron (from "wrought" meaning "worked"). It has a very low carbon content of around 0.05% by weight with good tensile strength and shock resistance but is poor in compression and the slag inclusions give the iron a typical grained appearance. Being relatively soft, it is ductile, malleable and easy to work and can be heated and forged into shape by hammering and rolling. It is also easy to weld.

      Because of the manual processes involved, wrought iron could only be made in batches and manufacturing was very costly and difficult to mechanise.

    • Cast Iron
    • Cast iron was first produced by the Chinese in the fifth century B.C.. The more advanced blast furnace used to smelt the iron ore needed to operate at temperatures of 1600°C or more, sufficient to melt the iron. In early blast furnaces charcoal was the source of the carbon reducing agent, but in 1709 Abraham Darby introduced a new process replacing charcoal with coke which produced higher quality iron at lower cost. The oxygen supply for burning the carbon and maintaining the reduction process is provided by means of blowing engine or air pump which blasts the air into the bottom of the cone shaped furnace. Early blowing engines were powered by waterwheels but these were superseded by steam engines once they became available. To remove or reduce the impurities present in the ore, limestone (CaCO3), known as the flux is added to the charge which continuously feeds the furnace from above. At the high temperatures in the furnace the limestone reacts with silicate impurities to form a molten slag which floats on top of the denser iron which sinks to the narrow bottom part of the cone where it can be run off through a channel into moulded depressions in a bed of sand. The slag is similarly run off separately from the top of the melt. Because metal ingots created in the moulds which receive molten iron from the runner resembled the shape of suckling pigs, the iron produced this way is known as pig iron.

      The design of the blast furnace enables cast iron to be made in a continuous process, greatly reducing the labour costs.

      Iron produced in this way has a crystalline structure and contains 4% to 5% carbon. The presence of the carbon atoms impedes the ability of the dislocations in the crystal lattice of the iron atoms from sliding past one another thus increasing its hardness. Pig iron is so very hard and brittle, and very difficult to work that it is almost useless. It is however reprocessed and used as an intermediate material in the production of commercial iron and steel by reheating to reduce the carbon content further or combining the ingots with other materials or even scrap iron to change its properties. Iron with carbon content reduced to 2% to 4%t is called cast iron. It can be used to create intricate shapes by pouring the molten metal into moulds and it is easier to work than pig iron but still relatively hard and brittle. While strong in compression cast iron has poor tensile strength and is prone to cracking which makes it unable to tolerate bending loads.

    • Steel
    • Steel is iron after the removal of most of the impurities such as silica, phosphorous, sulphur and excess carbon which severely weaken its strength. It may however have other elements, which were not present in the original ore, added to form alloys which enhance specific properties of the steel. Steel normally has a carbon content of 0.25% to 1.5%, slightly higher than wrought iron but it does not have the silicate inclusions which are characteristic of wrought iron. Removing the impurities gives the steel much greater strength but is an expensive and difficult task.

      Other alloying elements such as manganese, chromium, vanadium and tungsten may be added to the mix to create steels with particular properties for different applications. By controlling the carbon content of the steel as well as the percentage of different alloying materials, steel can be made with a range of properties. Examples are:

      • Mild steel the most common form of steel which contains about 0.25% carbon making it ductile and malleable so that it can be rolled or pressed into complex forms suitable for automotive panels, containers and metalwork used in a wide variety consumer products
      • High carbon steel or tool steel with about 1.5% carbon which makes it relatively hard with the ability to hold an edge. The more the carbon content, the greater the hardness
      • Stainless steel which contains chromium and nickel which make it resistant to corrosion
      • Titanium steel which keeps its strength at high temperatures
      • Manganese steel which is very hard and used for rock breaking and military armour
      • Spring steel with various amounts of nickel and other elements to give it very high yield strength
      • As well as others specialist steels such as steels optimised for weldability

      Mild steel has largely replaced wrought iron which is no longer made in commercial quantities, though the term is often applied incorrectly to craft made products such as railings and garden furniture which are actually made from mild steel.

Steel making has gone through a series of developments to achieve ever more precise control of the process as well as better efficiency.

1712 English blacksmith Thomas Newcomen built the world's first practical steam engine capable of doing dynamic mechanical work, not just pumping. It was an atmospheric engine using a piston to produce reciprocating motion. (See diagram of Newcomen's Steam Engine)

In its simplest form, a piston with a fixed connecting rod protruding from the top was mounted in a vertical cylinder above a water boiler. Steam from the boiler introduced at the bottom of the cylinder through a valve pushed the piston up to the top of its stroke. At the top of the stroke, the steam was shut off and the valve was closed trapping the steam inside. As in Savery's engine the cylinder was then cooled, in this case by spraying cold water into the cylinder under the piston to condense the steam. This is the power stroke of the piston in which condensing the steam creates a vacuum under the piston which pulls it back down to its bottom position, or in other words, the atmospheric pressure on the top of the piston pushes it down against the vacuum. This is what gives the engine the name of atmospheric engine.

The fixed piston connecting rod executed a reciprocating linear movement which could be harnessed to perform work.

In practical engines the piston rod was connected to one end a heavy beam balanced on a pivot above the engine. The power stroke of the piston produced a rocking motion of the beam pulling the end of the beam down while at the same time raising the other end of the beam. A second rod connected to the opposite end of the rod from the piston could be used to lift weights or water from great depths, however the actual lifting distance was limited by the stroke of the piston. The piston did not need high steam pressure to raise it to the top of its stroke because the unbalanced heavy weight of the lifting gear on the other end of the beam would tend to pull the piston upwards.

Before Newcomen, water pumps were horse drawn and were effective to a maximum depth of 90 feet (27 M). Newcomen's engine could draw water from several hundred feet enabling the operation of much deeper mines.

Because of the low operating steam pressures the engine was relatively safe. Efficiency however was very low because of the energy needed to reheat the steam chamber with every stroke and the time needed for heating and cooling it. Newcomen's first engine made twelve strokes per minute and raised ten gallons (45 Litres) of water per stroke. It was another 57 years before the next innovation in steam power, James Watt's separate steam condenser.

Because of the high consumption of coal to fuel the engine and its high cost, Newcomen engines were generally found only at pit heads where they were used for draining deep mines.

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1713 Prolific French scientist and entomologist René-Antoine Ferchault de Réaumur invents spun glass fibres. In an attempt to make artificial feathers from glass he made fibres by rotating a wheel through a pool of molten glass, pulling out threads of glass where the hot, thick liquid stuck to the wheel. His fibers were short and fragile, but he predicted that spun glass fibers as thin as spider silk would be flexible and could be woven into fabric.

In 1731 Réaumur also invented an alcohol thermometer and a corresponding temperature scale which both bear his name. The temperature scale assigned zero degrees to the freezing point of water and eighty degrees its boiling point. The freezing point was fixed and the tube graduated into degrees each of which was one-thousandth of the volume contained by the bulb and tube up to the zero mark. It was an accident dependent on the expansion of the particular quality of alcohol employed which made the boiling point of water 80 degrees.

1714 The first mercury thermometer was made by Polish inventor Gabriel Fahrenheit. It had improved accuracy over the alcohol thermometer due to the more predictable expansion of mercury combined with improved glass working techniques. At the same time Fahrenheit introduced a standard temperature scale based on the two fixed points of the freezing and boiling points of water.

1725 French weaver Basile Bouchon used a perforated paper roll in a weaving loom to establish the pattern to be reproduced in the cloth. The world's first use of manufacturing automation by using a stored program to control an automated machine.

1728 Another French weaver, Jean Falcon worked with Bouchon to improve his design by changing the perforated paper roll to a chain of more robust punched cards to enable the program to be changed more quickly.

1729 English chemist Stephen Gray was the first to identify the phenomenon of electric conduction and the properties of conductors and insulators and the first to transmit electricity over a wire. In an experiment, a young boy across laid across two swings suspended by silk ropes which insulated the boy electrically from the ground. The boy's body was charged up from a Hauksbee machine and when the boy held his hand above flakes of gold leaf on the floor, the flakes were picked up by electrostatic attraction to his hand. Thus electric charge was thus shown to be conducted through the boy's body to his hand but not through the insulating silk ropes to the ground.

Gray subsequently sent charges nearly 300 feet over brass wire and moistened thread and showed that electricity doesn't have to be made in place by rubbing but can also be transferred from place to place with conducting wire. An electrostatic generator powered his experiments, one charge at a time. The fore-runner to the electric telegraph.

1733 French soldier, diplomat and chemist Charles-Francois de Cisternay du Fay discovered two types of electrical charge, positive and negative which he called "vitreous" and "resinous" from the materials used to generate the charge.

1733 John Kay of Bury, Lancashire (No relation to John Kay of Warrington) patented the flying shuttle, the device used in weaving looms, which carries the weft threads (across the width of the cloth) between the warp threads (along the length of the cloth). In a traditional hand loom, the weft thread was held in a natural reed which was propelled by hand across the loom between the warp threads pulling the weft behind it along a track called the race. It was a slow process and to produce wide bolts of cloth, it needed two weavers, one at each side of the loom to catch and return the shuttle. In Kay's system, a mechanism at each end of the race caught the shuttle and sent it back to the opposite side. The shuttle itself was made of metal and being heavier than the reed it gave the shuttle more inertia to traverse the loom. This system enabled much faster weaving speeds and the production of greater widths of cloth with only one operator per loom instead of two as well as reduced manual intervention in the process.

The introduction of flying shuttle was however perceived as a threat to their livelihood by textile workers who resisted its introduction and Kay had great difficulty in collecting the royalties on his patents.

On the positive side, the increased production of cloth created a demand for thread which exceeded the industry's production capacity, prompting the mechanisation of the thread spinning process.

The invention of the flying shuttle was one of the first examples of mechanisation being used to improve productivity and a significant first step in the Industrial Revolution.

1733 French Huguenot mathematician, Abraham de Moivre living in England to escape religious persecution in Catholic France derived and published the formula for the Normal Distribution which he used to analyse the magnitude and the probability distribution of errors. Also called the Bell Curve and the Gaussian or error distribution but strangely never by de Moivre's name, besides describing the distribution of measurement errors it is widely used to represent the distribution of characteristics which cluster round a mean value such as the spread of tolerances on manufactured parts to anthropometrical and sociological data about the general population. See diagram of the Normal Distribution.

De Moivre also derived a law relating trigonometry to complex numbers which was indeed named after him. It states that for any complex number and for any real number X and integer n it holds that:

(cosx + i sinx)n = cos(nx) + i sin(nx)

He supplemented his meagre income as a mathematics tutor with a little gambling and the publication of his book The Doctrine of Chances: a method of calculating the probabilities of events in play one of the first books about probability theory which ran into four editions between 1711 and 1756.

1738 Swiss mathematician Daniel Bernoulli showed that Newton's Laws apply to fluids as well as solids and that as the velocity of a fluid increases, the pressure decreases, a statement known as the Bernoulli principle.

More generally the Bernoulli Equation is a statement of the conservation of energy in a form useful for solving problems involving fluid mechanics or fluid flow. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point.

Bernoulli's equation also underpins the theory of flight. Lift is created because air passing over the top of the wing must travel further and hence faster that air traveling the shorter distance under the wing. This results in a lower pressure above the wing than below the wing and this pressure difference creates the lift.

See also Diagrams of Aerodynamic Lift and Alternative Theories of Flight

Daniel Bernoulli was also the first to explain that the pressure exerted by a gas on the walls of its container is the sum of the many collisions by individual molecules, all moving independently of each other - the basis of the gas laws and the modern kinetic theory of gases.

Daniel Bernoulli was a member of a family of Bernoullis many of whom gained international distinction in mathematics. They were Calvinists of Dutch origin but were driven from Holland by religious persecution finally settling at Basel in Switzerland.

James (Jacques/Jakob) Bernoulli was the first to come to prominence. He learned about calculus from Leibniz and was one of the first users and promoters of the technique. In his Ars Conjectandi, "The Conjectural Arts" published in 1713, eight years after his death by his nephew Nicholas Bernoulli, he established the principles of the calculus of probabilities - the foundation of probability theory as well as the principles of permutations and combinations. He was also one of the first to use polar coordinates.

John (Jean/Johann) Bernoulli, James' brother and father of Daniel was clever but unscrupulous, fraudulently substituting the work of his brother James, of whom he was jealous, for his own to cover up his errors. He also banished his son Daniel from his home when he was awarded an prize he himself had expected to win. Nevertheless he was a great teacher an advanced the theory of calculus to explore the properties of exponential and other functions.

John's three sons Nicholas, Daniel and John Bernoulli the younger and his two sons John and James all achieved distinction in mathematics in their own right.

1740 British clockmaker Benjamin Huntsman, in search of spring steel for his clock making business, developed the crucible steel process to convert pig iron into steel. He chose Sheffield as the location for his business since it had a plentiful supply of good quality coke. His process essentially reheated pig iron with coke and limestone flux in small crucibles which could be more precisely controlled than large blast furnaces. It also allowed other alloying materials to be added to the mix to make specialist steels, but the method was only suitable for making small batches.

Huntsman was the first to make steel ingots, establishing Sheffield as a steel making town. He abandoned clockmaking, and instead used his crucibles for the more profitable manufacturing of high quality steels for arms, tools and cutlery (as well as springs) for which Sheffield became famous and "crucible steel" became synonymous with specialist steel made to precise specifications.

See also Iron and Steel Making

1744 Prolific French inventor Jacques de Vaucanson maker of robot devices and automatons playing musical instruments and imitating the movements of birds and animals, turned his attention to the problems of mechanisation of silk weaving. Building on the inventions of Bouchon and Falcon, he built a fully automated loom which used perforated cards to control the weaving of patterns in the cloth. Vaucanson also invented many machine tools and collected others which became the foundation of the 1794 Conservatoire des Arts et Métiers (Conservatory of Arts and Trades) collection in Paris. Although Vaucanson's loom was ignored during his lifetime, it was rediscovered more than a half century later at the Conservatoire by Jacquard who used it as the basis for his own improved design.

1745 Electricity first stored in a bottle (literally). The discovery of the Leyden Jar, essentially a large capacitor, was claimed by various experimenters but generally attributed to a Dutch physicist and mathematician Pieter van Musschenbroek and his student Andreas Cunaeus (whom he almost electrocuted with it) working at Leyden in Holland. The first source of stored electrical energy the Leyden jar was simply a jar filled with water, with metal foil around the outside and a nail piercing the stopper and dipping into the water.

A similar device was also invented at the same time by Ewald Jurgens von Kleist Dean of the Cathedral of Kammin in Germany.

The design was improved in 1747 by English astronomer John Bevis who replaced the water with an inner metal coating covering the bottom and sides nearly to the neck. A brass rod terminating in an external knob passed through a wooden stopper or cork and was connected to the inner coating by a loose chain or wire.

The invention of the Leyden jar was a key development in the eighteenth century and until the advent of the battery, Leyden jars, together with von Guericke's and Hauksbee's electrostatic generators, were the experimenters' only source of electrical energy. They were however not only made for scientific research, but also as curiosities for amusement. In the 18th century, everybody who had heard of it wanted to experience an electric shock. Experiments like the "electric kiss" were a salon pastime.

1746 French clergyman and physicist Jean Antoine Nollet demonstrated that electricity could be transmitted instantaneously over great distances suggesting that communications could be sent by electricity much faster than a human messenger could carry them.

With the connivance of the Abbot of the Grand Convent of the Carthusians in Paris he assembled 200 monks in a long snaking line with each monk holding the ends of eight metre long wires to form a chain about one mile long. Without warning he connected a Leyden Jar to the ends of the line giving the unsuspecting monks a powerful electric shock and noted with satisfaction that all the monks started swearing and contorting, reacting simultaneously to the shock. A second demonstration was performed at Versailles for King Louis XV, this time by sending current through a chain of 180 Royal Guards since by now the monks were less than cooperative. The King was both impressed and amused as the soldiers all jumped simultaneously when the circuit was completed.

1746 English mathematician and scientist, Benjamin Robins, constructed a whirling arm apparatus to conduct experiments in aerodynamics. He attached a horizontal arm to a vertical pole, which he rotated, causing the arm to spin in a circle. A variety of objects were attached to the end of the rotating arm and spun at high speed through the air. His tests confirmed that the size, the shape and the orientation of the objects had a tremendous effect on air resistance and the drag they experienced. This idea was subsequently picked up and used by others such as Smeaton who used it to derive the aerodynamic lift equation.

1747 - 1753 Fabulously wealthy, eccentric English loner Henry Cavendish discovered the concept of electric potential, that the Inverse Square Law applied to the force between electric charges, that the capacity of a condenser depends on the substance between the plates (the dielectric) and that the potential across a conductor is proportional to the current through it (Ohm's Law).

Charge was provided by Leyden Jars. Potential was "measured" by observing the deflection of the two gold leaves of an electrometer but since no instruments for the measurement of electric current existed at the time, Cavendish simply shocked himself, and estimated the current on the basis of the extent and magnitude of the resulting pain.

Cavendish also analysed the puzzle of the Torpedo fish which seemed to give an electric shock which was not accompanied by a spark. At that time the presence of a spark was considered to be an essential property of electricity. He was the first to make the distinction between, the amount of electricity (its charge), now called Coulombs, and its intensity (its potential difference), now called Volts. He showed that the fish produced the same kind of electricity as produced by an electrostatic generator or stored in a Leyden jar, but the electricity from the fish was high charge with low voltage whereas the electricity from a typical Leyden jar was high voltage with a low charge. We now know that the fish can generate a voltage of about 250 Volts while the voltage on the Leyden jar could typically be ten times that.

Cavendish recorded all his experiments in notebooks and manuscripts but published very little, principally the results of the chemical experiments which formed the bulk of his work. It was therefore left to Coulomb (1785), Ohm (1827) and Faraday (1837) to rediscover these laws many years afterwards. His papers were discovered over a century later by James Clerk Maxwell who annotated and published them in 1879.

Cavendish's family endowed the Cambridge University Cavendish Laboratories at which many of the world's discoveries in the field of nuclear physics were made.

1747 British physicist Sir William Watson, Bishop of Landaff, ran a wire on insulators across Westminster Bridge over the Thames to a point across the river over 12,000 feet away. Using an earth or ground return through the river. He was able to send a charge sufficiently intense after passing through three people to ignite spirits of wine. Watson was probably the first man to use ground conduction of electricity, though he may not have been aware of its significance at the time. Watson was the first to recognise that a discharge of static electricity is equivalent to an electric current.

1748 Watson uses an electrostatic machine and a vacuum pump to make a glow discharge lamp. His glass vessel was three feet long and three inches in diameter. The first fluorescent light bulb.

1748 To carry out measurements with less risk of electrocution of the experimenter or dragooned assistants Nollet invented one of the first electrometers, the electroscope, which detected the presence of electric charge by using electrostatic attraction and repulsion between two pieces of metallic foil, usually gold leaf, mounted on a conducting rod which is insulated from its surroundings. The first voltmeters.

1748 Swiss mathematician and physicist Leonhard Euler produced this remarkable formula:

eix = cos(x) + i sin(x)

where i = √-1

and e = 2.1828 the base of the natural logarithm, now known as Euler's number.

In the special case where x = π,     then cos(π) = -1 and sin(π) = 0

and Euler's formula reduces to:

ei π = -1

Euler had thus discovered a simple and surprising relationship between three mathematical constants.

Among his many other accomplishments, Euler developed equations for calculating the power and torque developed by hydraulic turbines.

1750 to 1850 The Industrial Revolution

In the period between 1750 and 1850 a series of technical innovations took place in Britain, each one with the simple aim of solving a particular problem or of doing things more efficiently, each one creating yet more opportunities for innovation. The way forward was shown by the development of rudimentary machines to improve productivity by mechanising manual work. The the advent of the steam engine raised the potential of this mechanisation to a much greater level. The following were some key developments:

  • (1701) Jethro Tull's seed drill, an early example of mechanisation revolutionised British agriculture.
  • (1709) Abraham Darby's mass production of cast and wrought iron provided the essential materials for building industrial tools and machines.
  • (1712) Thomas Newcomen invented the first practical steam engine which was first used for pumping water out of mines, but with further developments became the workhorse of the industrial revolution.
  • (1733) John Kay's hand operated flying shuttle brought mechanisation to the weaving industry.
  • (1759) Josiah Wedgwood founded his pottery factory. He used mass production techniques coupled with scientific method to determine precise controls on the composition of the glazes, the temperatures of the kilns and the glazing process to produce high quality ceramics. (A typical example of the possibilities of mechanised production of ceramic products. Not unique to Wedgwood). Wedgwood was instrumental in commissioning and funding the Trent and Mersey Canal which secured supplies for his potteries. He was also a pioneer in marketing and advertising, one of the first to open showrooms to display his products and to make skilful use of royal patronage to promote and sell them.
  • (1761) James Brindley extended the British canal system creating a national network facilitating the easier and more economical movement of goods.
  • (1764) James Hargreaves' spinning jenny, powered by hand, brought further mechanisation to the textile industry
  • (1765) Matthew Boulton introduced the factory system to the metalworking industry and provided social security for his employees.
  • (1769) James Watt greatly improved the efficiency of steam engines improving the economic viability of steam power.
  • (1771) Richard Arkwright developed much larger machine driven spinning frames which he installed at Cromford Mill where he pioneered the factory system of production in the spinning industry.
  • (1779) Samuel Compton invented the spinning mule which could produce a wide range of high quality fine yarns.
  • (1786) Matthew Boulton applied steam power to coining machines to manufacture coins for the mint. (A typical example of the possibilities of mechanised production of metal parts. Not unique to Boulton)
  • (1794) Eli Whitney in the USA invented the cotton gin which revolutionised the processing of raw cotton.
  • (1797) Henry Maudslay and James Naysmith developed precision machine tools while Joseph Whitworth in Manchester and Eli Whitney in the USA pioneered manufacturing using interchangeable parts.
  • (1825) George Stephenson opened the worlds first public railway initiating a rapid improvement in the country's transport infrastructure.

Taken together these innovations had a profound and unprecedented affect on society and social, economic and cultural conditions.

Though not fully exploited at the time, several important discoveries were also made towards the end of the period, which laid the ground work for a second wave of innovation based on electrical communications, electric power, computers and household appliances. These were;

What were the results of all of this innovation?

Production methods were mechanised reducing costs and the steam engine enabled factories to use very large machines to achieve even greater levels of mechanisation reducing costs even further. The new transport infrastructure created by the canals and later by the railways made it cheaper and easier to access lower cost supplies of raw materials as well as giving access to new markets for the products produced by the factories. Manufacturing activities which had previously not been economically viable suddenly became possible. New employment opportunities were created with jobs that previously didn't exist such as engineers, draughtsmen, machine builders, tool makers, managers, book keepers and salesmen and with these jobs came the possibility of social mobility. Overall, incomes rose and were more regular and secure, the cost of manufactured goods was reduced, more manufactured goods were available and there was a sustained increase in the economic well being of the country.

But there were consequences of these developments. Cottage industries could not compete with mechanised factories and went out of business. The demand for craftsmen, proud of their skills and workmanship was replaced by the demand for unskilled factory workers to operate machines and to assemble the products. The result was that there was a movement of the rural population towards the towns where living conditions were often unhealthy and far from ideal.

Although conditions in the towns were sometimes grim, the romantic view that industrialisation was a catastrophe and that rural life before these changes took place was idyllic, is unrealistic. The reality of previous rural life was also less than ideal. It may have been a more healthy environment in the country but people still lived in poverty. They still used child labour. Incomes were very low and irregular or uncertain, the population was generally illiterate and subject to the demands of landlords who were not necessarily any more benevolent than factory owners and there were fewer opportunities for personal development and social mobility to escape from this poverty.

The Industrial Revolution marked the end of feudalism and the beginning of social mobility.

How did this great transformation come about?

The industrial revolution is characterised by the development of an industrial economy resulting from the ever increasing flow of innovative practical products based on the application of new technologies, mechanised production methods and the availability of mechanical power to make it happen. But for these new ideas to flourish, they had to fall on fertile ground and these conditions were found in Britain in the second half of the eighteenth century and the first half of the nineteenth century.

  • The previous two hundred years had seen the flowering of the Scientific Revolution when great thinkers, no longer hampered by censorship of new ideas by the church, provided a theoretical basis for the way things worked. Amongst others, Newton provided the Laws of Motion and Calculus, Boyle and Charles provided the Gas Laws and Hooke provided the Law of Elasticity.
  • Improved methods of time and temperature measurement were also available enabling more accurate scientific experiments to be performed.
  • The country had six universities, founded before 1600, carrying out scientific research and teaching. (Oxford, Cambridge, St Andrews, Glasgow, Aberdeen, Edinburgh)
  • Scientific societies such as the Royal Society (founded 1660), the Lunar Society of Birmingham (dating from 1765) and the Royal Institution (founded 1799), encouraged the sharing and dissemination of ideas.
  • Towards the end of the eighteenth century and during the first half of the nineteenth century, Literary and Philosophical Societies were founded in many British towns and cities, particularly in the north. Known as the "lit and phils" they provided the opportunity to discuss intellectual issues of the day and to sponsor cultural activities. Amongst their aims were education and the advancement of science and technology but in the days when there were few forms of public entertainment and recreation, they coincidently provided the opportunity for socialising and networking and so attracted a large membership. Lectures and presentations at the "lit and phils" were thus well attended and news about technology and potential investment opportunities reached a wide audience of interested and often influential people.
  • The country was being denuded of wood used for fuel but it was self sufficient in energy from coal, which contained more than three times the energy of wood, and hydro power as well as many key raw materials such as iron ore.
  • Good, stable economic conditions prevailed in the country.
  • Most European countries at the time were ruled by absolute monarchies. Decision making tended to be concentrated in a few hands and high up on their priority list were self preservation and control of their subjects, often accompanied by expansionist territorial aspirations backed by military power.
  • Britain too had international aspirations but by contrast, it had just agreed a "Bill of Rights" in 1689 restricting the power of the crown and enhancing the power of parliament. While power was not completely devolved, members of parliament ensured that regional issues got a sympathetic hearing. Priorities such as local transport infrastructure development and the promotion and protection of commerce were higher up the priority list.

  • Certain regions of the country had well organised cottage industries with established industry skills, supplies and trade routes which provided a fertile environment for the introduction of new technologies. A prime example was Lancashire which, because of its damp climate, had a large cotton processing industry with a concentration of textile producers using cotton imported from qualified trading partners. (Originally from India, but progressively from the West Indies and the American colonies.)
  • The rule of law prevailed with contract law and patent law providing legal protection to business and to inventors.
  • Profit flows from trade with the colonies accumulated in Britain creating a capital surplus which was available to be invested in factories, machinery, canals and railways. Similarly this influx of wealth created a new demand for manufactured goods for use in the home.
  • The development of the transport infrastructure dramatically reduced the costs of transporting heavy and bulky raw materials such as coal, iron ore and clay for the potteries as well as the distribution of finished goods enabling new resources to be tapped and new markets to be reached.
  • Joint stock companies were able to provide funding enabling longer term or large projects to be undertaken.
  • The country had a tradition of free market capitalism supported by parliament and a stock exchange (The Royal Exchange opened by Queen Elizabeth I in 1571) to enable the trading of shares.
  • Insurance was available to underwrite risks. (Insurance deals were traded in Lloyd's Coffee House in London from 1688, initially, mainly for maritime risks)
  • Towards the end of the period, Building Societies were established enabling people to purchase their own property and Hire Purchase Contracts were introduced in support of the sales of sewing machines enabling the set up of small family businesses, both of which in their small way helped to bring about the beginnings of social mobility and the possibility for more people to realise their full potential.

The industrial revolution started in Britain but it was quickly followed in Western Europe, then North America, followed by Japan and eventually the rest of the world (at least most of it).

1750 Nollet demonstrated the astonishing efficiency of electrostatic spraying, an idea which was not put to practical use until it was rediscovered by Ransburg in 1941.

1750 English physicist John Michell describes magnetic induction, the production of magnetic properties in unmagnetised iron or other ferromagnetic material when it is brought close to a magnet. He discovered that the two poles of a magnet are of equal strength and that they obey the inverse-square law for magnetic attraction in "A Treatise on Artificial Magnets".

1752 French experimenter Thomas François Dalibard, assisted by retired illiterate old dragoon M. Coiffier, carried out an experiment proposed by Benjamin Franklin. They set up their experiment at Marly la Ville and from a safe distance (in Dalibard's case eighteen miles away) they waited for a storm. They used a long pointed iron rod, placed upright in a wine bottle and insulated from the ground by more glass bottles, to attract a lightning discharge from a thunder cloud. Coiffier subsequently drew electrical sparks from the charged rod to prove that thunder clouds contain electricity and that it can be conducted down a metal rod.

1752 A man of many talents, Benjamin Franklin one of the leaders of the American Revolution and founding fathers of the USA, journalist, publisher, author, philanthropist, abolitionist, public servant, scientist, diplomat and inventor carried out his famous kite experiments in 1752, one month after Dalibard, and invented the lightning rod.

Franklin proposed a "fluid" theory of electricity and outlined the concepts of positive and negative charges, current flow and conductors coining the language to describe them. Words such as battery (from an array of charged glass plates, and later, a number of Leyden Jars), charge, condenser (capacitor), conductor, plus, minus, positively, negatively, armature, electric shock and electrician all of which we still use today.

Du Fay in 1733 had first described the concept of two types of electric charges, "vitreous" and "resinous". Franklin explained that current flow was the flow of a positive charge towards negative charge to cancel it out. Using the water analogy he named the point of high potential, (from which the water flows) as the positive terminal with the lower potential terminal being negative. Current can also be associated with the flow of positive ions from the positive terminal to the negative terminal, or with the flow of negatively charged electrons from the negative terminal to the positive terminal. Nowadays we tend (lazily) to associate current flow exclusively with electron flow, overlooking the equally valid positive ion flow, which leads to the confusion and the incorrect charge that Franklin got it wrong by defining the current flow in the opposite direction from which electrons flow.

The purpose of Franklin's kite experiment was to confirm that lightning was another manifestation of electricity. Legend has it that he flew a kite into a thunder cloud to pick up an electric discharge from the cloud. The electric charge was then conducted down the wet kite string to which a key had been attached near the ground and that sparks were emitted from the key which were used to charge a Leyden jar, thus proving that an electric charge came from the clouds.

Whilst it may be heresy to suggest that Franklin did not actually carry out the kite experiment for which he is famous, there are no reliable witnesses to this event and it is a fact that nobody, including Franklin, has yet been able to duplicate this experiment in the manner he described, and few have been willing to try. One who did was Professor Georg W Richmann a Swedish physicist working in St Petersburg who was killed in the attempt on 6 August 1753. He was the first known victim of high voltage experiments in the history of physics. Benjamin Franklin was lucky not to win this honour.

1752 Johann Georg Sulzer notices a tingling sensation when he puts two dissimilar metals, just touching each other, on either side of his tongue. It became known later as the battery tongue test: - the saliva acting as the electrolyte carrying the current between the two metallic electrodes.

1753 A proposal is submitted in an anonymous letter to the Scotsman Magazine signed "C.M.", generally attributed to Scottish surgeon Charles Morrison, for 'An Expeditious Method of Conveying Intelligence'. It described an electrostatic telegraph system using 26 insulated wires to conduct separate charges from a Leyden Jar causing movements in small pieces of paper on which each letter of the alphabet is written.

1757 French botanist Michel Adanson proposed that the discharge from the Senegalese (electric) catfish could be compared with the discharge from a Leyden jar. The ability of certain torpedo fish or sting rays to inflict electric shocks had been known since antiquity however Adanson's theory was new. It was later proved by British administrator and M.P., John Walsh, secretary to Clive of India, who in 1772 managed to draw a spark from an electric eel. It is quite possible that news of Walsh's experiment influenced Galvani to begin his own experiments with frogs.

1759 German mathematician Franz Maria Ulrich Theodosius Aepinus published his book, An Attempt at a Theory of Electricity and Magnetism. The first work to apply mathematics to the theory of electricity and magnetism, it explained most of the then known phenomena.

In 1789 Aepinus also made the first variable capacitor which he used to investigate the properties of dielectrics. It had flat plates which could be moved apart and different materials could be inserted between them. Volta also laid claim to the invention of this device and to giving it the name of "capacitor".

1759 English civil engineer, John Smeaton constructed a whirling arm device for investigating the aerodynamic properties of windmills and windmill vanes. It was based on an earlier design by Benjamin Robins and had the same functions as a modern wind tunnel but instead, it consisted of a vertical shaft supporting a rotating arm on which to mount models of windmill vanes which could be made to pass at high speed in a circular path through the still air to determine their relative efficiency. (See diagram of Smeaton's Whirling Arm) At the same time the blades could be rotated by means of a falling weight attached by a cable to a pulley on the windmill shaft. It was used to investigate the effects of camber and angle of attack of the blades.

Using the apparatus, Smeaton determined that the force L on a plate or blade (or aerodynamic lift in the case of wings) is given by:



k is the drag in pounds weight of a 1-square-foot (0.093 m2) plate at 1 mph, known as the Smeaton coefficient

V is is the velocity of the air over the plate in miles per hour

A is the Area of the plate in square feet

CL is the magnitude of the lift relative to the drag of a plate of the same area, known as the lift coefficient

This relationship is known as the lift equation and was used by the Wright brothers in the design of their wings and propellers, though from their wind tunnel experiments they determined a more accurate value for the coefficient k.

Smeaton is more well known for the many bridges, canals, harbours and lighthouses that he built. He coined the term "civil engineers" and in 1771 founded the Society of Civil Engineers the forerunner of the Institution of Civil Engineers.

1761 Scottish chemist and physicist Joseph Black working at Glasgow University, discovered that ice absorbs heat without changing temperature when melting. Between 1759 and 1763 he evolved the theory of latent heat for a heat flow that results in no change of temperature, that is, for the heat flows which accompany phase transitions such as boiling or freezing. He also showed that different substances have different specific heats, the amount of heat per unit mass required to raise its temperature by one degree Celsius.

James Watt was his pupil and assistant.

1761 Self taught, English engineer, James Brindley son of a farmer, opened the Bridgewater Canal which he had designed and built for Francis Egerton the third Duke of Bridgewater to carry coal from his coalmine at Worsely to market in Manchester, ten miles away. Transporting coal by canal boat rather than by pack horse reduced its cost by 50%. The Bridgewater Canal was the first British canal not to follow an existing water course. Instead he chose a more level route by following the contours of the land to simplify construction, avoiding embankments and tunnels as well as the need for the traditional, time-wasting locks. It did however require the construction of an aqueduct at an elevation of 39 feet (13 M) to carry it over the River Irwell, a feature which was unique at the time. The sight of a barge floating high up in the air became one of the first tourist attractions of the Industrial Revolution.

Brindley went on to build another 300 miles of canals. His Bridgewater canal marked the beginning of Britain's golden era of canal building from 1760 to 1830 during which the country's new inland waterway system linked up the otherwise isolated local canals serving the country's major cities into a national network, greatly improving the nation's transport infrastructure.

Before the canal system was built, the transport of bulky goods was prohibitively expensive. They were either sent by sea or overland by pack horse. This meant that users had to be located close to their source of supply or to the docks. Factories depending on steam engines had to be located near to coal mines. But canals changed all that. One canal boat, operated by one man and a horse, could carry as much as a hundred pack horses. Transport by canals cut the costs for industry and provided economic justification for new ventures which previously may not have been viable. Canals were the Motorways of the eighteenth century.

An practical example of the economic benefits of canals was the saving the pottery industry centred on Stoke on Trent. The potteries were originally located there because of the availability of suitable clay and the coal to fire it, but in the 1760s when supplies of local clay were becoming exhausted and markets demanded pottery made with finer clay from other sources, Brindley's Trent and Mersey Canal, opened in 1777, enabled the potters to bring in clay from Dorset, Devon and Cornwall by canal from the seaport rather than to move their business to other locations which may have had the clay but not the coal.

The Trent and Mersey canal necessitated the construction of the Harecastle Tunnel which was 1.64 miles (2633 m) long. It took seven years to construct and when it was completed in 1777 it was more than twice the length of any other tunnel in the world at that time. It was however only 9 feet (2.74 m) wide since it did not have a towpath so that boats had to be “legged“ through it by men lying on their backs and “walking“ on the roof taking 2 to 3 hours to pass through the tunnel. It was also too narrow to take boats going in both directions so boats had to be grouped and one way system allowed the direction of travel to be changed after each group had passed through. Some enterprising local men offered their service as “leggers“ to help speed the boats through.

Brindley died before the canal was completed.

To relieve congestion a second, wider tunnel with a towpath, parallel Brindley's tunnel was commissioned fifty years later. It was slightly longer at 1.66 miles (2675 m) and was built by Thomas Telford. Taking just three years to complete, it was opened in 1827.

The advent of George Stephenson's faster rail transportation brought this golden era to an end.

1764 After the introduction of the flying shuttle which improved the productivity of the weaving industry, the demand for cotton yarn outstripped supply, and the cottage industry producing it, one thread at a time, on traditional spinning wheels could not keep up. In the 1760s several inventors developed machines to mechanise this process.

The first was James Hargreaves of Blackburn, Lancashire who in 1764 invented a multi-spool spinning frame which dramatically reduced the labour content of the work. It was called the spinning jenny ("jenny" derived form "engine"), a machine for spinning, drawing and twisting cotton. It consisted eight spindles driven by a single large handwheel which turned all the spindles. Cotton was drawn from eight separate rovings, long thin bundles of cotton fibre, lightly clasped between two horizontal bars then wound onto the spindles. The spindles were mounted on a moveable carriage which allowed the roving to be stretched as it was pulled away from the clasping bars, imparting a twist to the cotton. He sold several machines but kept his activities secret at first. However the selling price of yarn fell as the production increased while at the same time the employment of local spinners was reduced culminating in his house being attacked and his machines smashed. As a result Hargreaves moved to Nottingham in 1768 where he eventually patented his machine in 1770.

An improved spinning machine, called a spinning frame was invented in 1767 by John Kay a clockmaker from Warrington, Lancashire (No relation to John Kay of Bury) who made improvements to Hargreaves design. Instead of the simple clasp used by Hargreaves to stretch the cotton fibre roving, the roving was passed between three sets of rollers, each set rotating faster than the previous one, progressively reducing the thickness of the roving and increasing its length before a strengthening twist was added to the yarn by a separate mechanism. This produced a much finer and stronger cotton yarn. The spinning frame was also called a water frame when it was powered by a water wheel.

At the time Kay was employed by Richard Arkwright, of Preston, Lancashire, who controversially patented Kay's machine in 1769 under his own name without telling Kay. This resulted in a scandal and caused a protracted patent dispute which involved yet another inventor of a spinning machine, Thomas Highs, of Leigh, Lancashire, who had worked with both Arkwright and Kay who were both familiar with his work. Highs had invented several devices for processing wool and cotton but didn't have the finance to develop his ideas and like Hargreaves, he had worked in secret on his spinning machine which he claimed to have patented in 1769. All the protagonists eventually lost out in the legal proceedings as the jury found against Arkwright but no rights were ever transferred to Highs or Kay.

As the technology of the day advanced, the available power to turn the spindles was increased, evolving from the machine operator himself, to horses, then water wheels and finally to steam engines (now electric motors). This enabled much larger spinning frames carrying over 100 spindles to be constructed, greatly increasing the productivity.

Arkwright was more of a businessman, rather than an inventor. In 1771, he built the world's first water-powered textile mill at Cromford in Derbyshire where he installed production equipment driven by water power in a highly a disciplined factory with workers operating machines in 13 hour shifts with little free time, replacing the local cottage industries where whole families, including their children, developed specialist skills working together at home on traditional crafts and trades. The factory work by comparison was unskilled with the work divided into short repetitive tasks and the employees, in both situations, were mostly illiterate since this was before the advent of universal education in Britain. Most of the employees were women and children, some as young as seven, though this was later increased to ten years old. It sounds horrific, but for his times, Arkwright was an enlightened employer, building houses for his employees and providing the children six hours of education per week so they could take on tasks such as record keeping. His Cromford Mill was the start of the factory system which was quickly copied by others and became a hallmark of the Industrial Revolution.

1765 Matthew Boulton who traded in ornamental metalware such as buttons, buckles and watch chains which were made in small workshops in and around Birmingham, opened the Soho Manufactory at Soho near Birmingham to bring all his business activities together under one roof, under his own ownership and control. Previously the goods were manufactured either in Boulton's own workshops or in the workshops of local independent artisans of which there were many in the Birmingham area.

The Soho Manufactory was a three-story building which housed a collection of small specialist workshops carrying out a range of metalworking process such stamping, cutting, bending and finishing as well as showrooms, design offices, stores, and accommodation for the employees. It was the world's first factory with machines powered by a steam engine.

Boulton was a benevolent employer. Instead of subcontracting work to other workshops in town, he employed the same skilled craftsmen who had worked in the workshops which he had displaced. Working conditions were good, employment was secure and he paid them well. Labour saving jigs and tools were used to improve productivity as well as the quality of the goods produced, designs were rationalised to achieve economies of scale by using interchangeable or common components. In this way Boulton was able to take on high volume production of items such as coins for the mint as well as fine, high quality products such as jewellery, silverware and plated goods.

He refused to employ young children as in some other industries and later introduced a very early social insurance scheme, funded by workers' contributions of 1/60th of their wages, which paid benefits of up to 80% of wages to staff who were sick or injured.

At its height the factory employed a thousand people in what was the largest and most impressive factory in the world becoming Birmingham's foremost tourist attraction.

Boulton's manufactory established the factory system in the metalworking industry, mirroring changes being made in the textile industry. Another step in the Industrial Revolution.

In 1769 Matthew Boulton also provided the financial backing and the manufacturing capability for the commercialisation of Watt's Steam engine.

1765 A group of prominent figures in the British Midlands, including industrialists, natural philosophers and intellectuals, set up an informal learned society later called the Lunar Society because it met during the full moon to take advantage of the lighter evenings for travelling home after meetings. Members included Matthew Boulton, James Watt, physician and inventor Erasmus Darwin, grandfather of Charles Darwin discoverer of the Theory of Evolution, Josiah Wedgwood and Joseph Priestley. Benjamin Franklin also attended a meeting of the society while visiting Birmingham and kept in touch with members.

1766 Swiss physicist, geologist and early Alpine explorer Horace Benedict de Saussure invents the first true electrometer for measuring electric potential by means of attraction or repulsion of charged bodies. It consisted of two pith balls suspended by separate strings inside an inverted glass jar with a printed scale so that the distance or angle between the balls could be measured. It was de Saussure who discovered the distance between the balls was not linearly related to the amount of charge.

1766 Hydrogen discovered by Henry Cavendish by the action of dilute acids on metals.

1767 English clergyman, philosopher and social reformer Joseph Priestley at the age of 34 made his first foray into the world of science with the publication of a two-volume History of Electricity in which he argued that the history of science was important since it could show how human intelligence discovers and directs the forces of nature. The previous year in London he had met Benjamin Franklin who introduced him to the wonders of electricity and they became lifelong friends. Priestley's first discovery, also in 1767, was that carbon conducts electricity.

Though he had no scientific training, Priestley is however better known as a chemist. He isolated Carbon dioxide, which he called "fixed air", and in a paper published in 1772, he showed that a pleasant drink could be made by dissolving the gas in water. Thus was born carbonated (soda) water, the basis of the modern soft drinks industry.

He was a great experimenter discovering Nitrous oxide (laughing gas) and several other chemical compounds and unaware of the work of Scheele in 1774 he independently discovered Oxygen. Priestley was no theorist however and he passed on his results to the French chemist Lavoisier who repeated the experiments taking meticulous measurements in search of underlying patterns and laws governing the chemical reactions.

Experimenting with growing plants in an atmosphere of Carbon dioxide, Priestley observed that the plants consumed the Carbon dioxide and produced Oxygen, identifying the process of plant respiration and photosynthesis. This was the first connection between chemistry and biology.

As a reformer, Priestley was a strong supporter of the 1776 American and the 1789 French Revolutions. This brought him into conflict with conservatives and in 1791 angry mobs burnt down his house and his church destroying many of his manuscripts. The intimidation continued until 1794 when the aristocratic Lavoisier, on the opposite side of the revolutionary fence from Priestley, was executed by French revolutionaries. A few weeks later Priestley emigrated to America to escape persecution spending the rest of his life there.

1769 The introduction of Watt's Steam Engine was a key event in the Industrial Revolution.

James Watt, a Scottish instrument maker working at the University of Glasgow in 1763 was given the job of repairing a model of Newcomen's 1712 steam engine. He noted how inefficient it was and between 1763 and 1775 he developed several improvements to the design. The most important of these was the introduction of a separate, cold, chamber for condensing the steam which avoided the need to heat and cool the main cylinder which could be kept hot while the steam was condensed in the cold condensation chamber. (See diagram of Watt's Steam Engine)

As in Newcomen's engine, steam introduced under the piston drove it to the top of its stroke at which point the steam was shut off, but the atmospheric power stroke was different. When the piston reached the top of its stroke a valve at the lower part of the cylinder opened releasing the steam into the cold chamber where it condensed, reducing the pressure under the piston which was pushed down by atmospheric pressure on the top of the piston. The use of the separate condenser reduced the heat losses in every cycle and led to a dramatic improvement in the fuel efficiency and speed of the engine and was the basis of Watt's patent in 1769.

Watt's original engine, like Newcomen's, generated most of its mechanical power, that is its atmospheric power, on the downstroke but not on the upstroke and this intermittent power delivery was not suitable for producing smooth, continuous rotary motion. To overcome this drawback, Watt developed a second innovation which was to introduce steam on top of the piston at the top of its stroke as well as below the piston at the bottom of its stroke. This second steam supply pushed the piston down with the steam being exhausted from above the piston into the cold chamber at the end of the down stroke thus creating a double-acting engine with the steam pushing and the vacuum pulling the pistons on both the up and down strokes. A double benefit of this system was that it also improved the efficiency still more. This idea was later developed by Trevithick and others for use in high pressure, horizontal engines.

(See Double Acting Piston).

Watt initially had difficulty in both manufacturing and commercialising his engine but this problem was solved when he entered into partnership in 1769 with Matthew Boulton, a Birmingham manufacturing entrepreneur. The Boulton and Watt company they founded was able to fund the further development of Watt's engines and to manufacture them with improved precision at Boulton's Soho plant. Their engines used only 20% to 25% of the coal used by the Newcomen engines to generate the same power and Boulton was instrumental in securing a patent for the steam condenser which meant that any user of the condenser technology had to pay substantial monthly royalties to the company and this was rigidly enforced.

The steam engine was quite literally the driving force behind the Industrial Revolution, freeing people from back breaking work, providing prodigious mechanical power to drive factories and machines enabling a myriad of applications as well as powering the railways thus facilitating trade and travel. The prime movers used for driving the first electricity generating plants by Schuckert, Edison and Ferranti starting in 1878 were also powered by large reciprocating steam engines based on James Watt's technology. The result was that Watt is commonly credited as the father or inventor of the steam engine and with bringing about the birth of and exploitation of this technology but there were many other contributors.

The following are some of the other key technologies and inventions associated with the development of the steam engine and it applications.

1770 French military engineer, Nicolas-Joseph Cugnot built his "fardier à vapeur", a three wheeled, steam driven military tractor, the world's first self propelled road vehicle, based on a smaller model he had produced the previous year. It was a mechanised version of the massive two-wheeled horse-drawn dray or wagon, known in France as a "fardier", used for transporting very heavy military artillery equipment.The boiler and driving mechanism were mounted on a single front wheel at the front of the vehicle replacing the horses. (See picture of Cugnot's Steam Carriage).

The engine used two vertically mounted single acting pistons, acting directly over the wheel, one on each side, with the piston rods connected to a rocking bar, pivoted at the centre, which allowed the piston movements to be synchronised in opposite directions. High pressure steam was applied alternately to the pistons so that the power stroke pushing one piston down caused the opposite piston to move back up ready to start its power stroke. Mounted on the driving axle were two disks one on each side of the single driving wheel, each disk with a ratchet or notches around its circumference. Power was transferred to alternate sides of the wheel by means of the piston rods with pawls which engaged on the ratchets on the down stroke to turn the wheel and slid over the ratchets on the up stroke while the drive was transferred to the disk on the opposite side of the wheel. This arrangement is considered to be one of the early successful devices for converting reciprocating motion into rotary motion. It was also the fore-runner of the freewheel mechanism.

The driving wheel and engine assembly were articulated to the rest of the cart and steering was by means of a lever (tiller steering) which turned the whole driving assembly including the boiler. The vehicle weighed in at over 2 tons and was designed to carry a load of 4 tons at a speed of 2.5 miles per hour. The massive boiler overhung the front of the wheel and made the vehicle somewhat unstable and, since there was no provision for carrying water or fuel, the vehicle needed to stop every ten to fifteen minutes to replenish the water and fuel and relight the boiler fire to maintain the steam pressure.

Cugnot was ahead of his time. Trials in 1771 by the French Army showed up the vehicle's limited boiler performance and difficulties in traversing rough terrain and climbing steep hills and rather than developing the invention, they abandoned the experiment. In 1772 Cugnot was awarded a pension by King Louis XV for his work but this was withdrawn with the start of the French revolution in 1789, and he went into exile in Brussels, where he lived in poverty until he was invited back to France by Napoleon Bonaparte shortly before he died in 1804. His fardier was kept at the military Arsenal until 1800 when it was transferred to the Conservatoire National des Arts et Métiers where it remains on display to this day.

See more about Steam Engines


1771 The world's first machine powered factory began operations in Cromford, Derbyshire. English inventor Richard Arkwright pioneered large scale manufacturing using a water wheel to replace manual labour used to power the spinning frames in his cotton mill.

1771 German-Swedish pharmaceutical chemist, Carl Wilhelm Scheele discovered Oxygen and two years later Chlorine. A prolific experimenter he is also credited with the discovery of the gases Hydrogen fluoride, Silicon fluoride, Hydrogen sulfide, Hydrogen cyanide. In addition he isolated and characterised glycerol, lactose, and ten of the most familiar organic acids including tartaric acid, citric acid, lactic acid and uric acid.

He was also the first to report the action of light on silver salts which became the basis of photography for over 180 years.

He received very little formal education and lived a simple life in a small town so his many achievements received little publicity. One result of this comparative obscurity is that others independently retraced his paths and were later credited with the discoveries he had already made, Priestley for Oxygen in 1774 and Davy for Chlorine in 1810.

Scheele was found dead in his laboratory at the age of 43, his death probably caused by exposure to the many poisons with which he worked. It was not unknown for scientists of his day to taste the chemicals with which they were working.

1774 An electrostatic telegraph is demonstrated in Geneva, Switzerland by Frenchman George Louis LeSage. He built a device composed of 24 wires each contained in a glass tube to insulate the wires from each other. At the end of each wire was a pith ball which was repelled when a current was initiated on that particular wire. Each wire stood for a different letter of the alphabet. When a particular pith ball moved, it represented the transmission of the corresponding letter. Intelligible messages were transmitted over short distances and LeSage's system is considered to be the first serious attempt at making an electrical telegraph.

1775 Like many experimenters of his time Alessandro Volta constructed his own Perpetual Electrophorus (that which carries off electricity) to provide a regular source of electricity for his experiments. It was crude and consisted of a resin plate on which was rubbed cat's fur or a fox tail and another insulated metal plate for picking up the charge.

1775 In response to the demands of the armaments industry the nascent steam power industry English engineer John Wilkinson made one of the first precision machine tools, a cylinder boring machine. His machine secured for him the largest share in the profitable business of supplying cannons in the American War of Independence. Wilkinson is reputed to be Britain's first industrialist to become a millionaire.

1775 Richard Ketley, the landlord of Birmingham's Golden Cross Inn, founded the first Building Society. It was a mutual financial institution owned by its members originally offering them savings and mortgage lending services. Members of Ketley's society paid a monthly subscription to a central pool of funds which was used to finance the building of houses for members, which in turn acted as collateral to attract further funding to the society, enabling further construction. The idea quickly caught on and building societies were soon established in many cities of the UK. More recently, building societies have expanded into the provision of banking and related financial services to their members.

1779 The world's first iron bridge, built across the River Severn Gorge at Coalbrookdale in Shropshire, was opened. It was designed by Thomas Farnolls Pritchard a local architect from Shrewsbury with a span of a 100 feet (30 m) and was built by the iron maker Abraham Darby III, grandson of Abraham Darby, and is still in use as a pedestrian bridge today. The bridge is a surprisingly graceful design, build from cast iron, but since there was no experience in using cast iron, or any other metal, as a structural material the design used techniques based on the more familiar carpentry using slender, custom designed castings in compression, connected together using mortise and tenon and blind dovetail joints.

The bridge was an engineering marvel in its day.

Shares were issued in 1775 to raise the £3,200 estimated cost of the bridge, but Darby found it difficult to find investors and had to give a personal guarantee to cover any costs incurred in excess of this estimate. He was awarded the contract to build the bridge and to supply the iron work from his Coalbrookdale plant and construction was eventually started in 1777 but the actual cost of building the bridge turned out to be £6,000 and resulted in Darby being in debt for the rest of his life.

1779 English inventor, Samuel Crompton invented the spinning mule so called because it is a hybrid which combined the moving carriage of Hargreaves' spinning jenny with the rollers of Arkwright's water frame in the same way that a mule is the product of cross-breeding a female horse with a male donkey. The spinning mule was faster and provided better control over the spinning process and could produce several different types of yarn. It was first used to spin cotton, then other fibres enabling the production of fine textiles.

1780 English inventor James Pickard patented the crank and flywheel to convert reciprocating motion of Newcomen's engine to rotary motion. He offered the patent rights for his device to Boulton and Watt in return for the rights to use Watt's patent for the separate condenser. Watt refused and instead designed a sun and planet gear to circumvent Pickard's patent. Once Pickard's patent expired, Boulton and Watt adopted the crank drive in their engines. The Sun and planet gear was actually designed in 1781 by William Murdoch, an employee of Boulton and Watt, but it was patented in Watt's name.

The sun and planet gear mechanism used two spur gears and was much more complex then the crank mechanism. In this application, the sun gear was fixed to the axle or output shaft and did not rotate about the axle, rather it rotated with the axle. The planet gear also does not rotate on its axis but was fixed to the end of the connecting rod. The reciprocating motion of piston causes the end of the connecting rod on which the planet gear wheel is mounted to trace a circular path around the sun gear causing the sun gear, and hence the output shaft to which is attached, to rotate.

See more about Steam Engines


1782 French mathematician Pierre-Simon Laplace, building on earlier work by Swiss mathematician Leonhard Euler, develops a mathematical operation now called the Laplace Transform as a tool for solving linear differential equations. The most significant advantage is that differentiation and integration become multiplication and division, respectively. This is similar to the way that logarithms change an operation of multiplication of numbers into the simpler addition of their logarithms. By applying Laplace's integral transform to each individual term in differential equations, the terms can be rewritten in terms of a new variable "s" and the equations are converted into polynomial equations which are much easier to solve by simple algebra. The solutions to the original problems are retrieved by applying the Inverse Laplace Transform.

This technique simplifies the analysis control systems and analogue circuits which are characterised by time varying differential equations. Laplace's method thus transforms differential equations in the time domain into algebraic equations in the s-domain.

Between 1799 and 1825 Laplace published in five volumes "Traité de Mécanique Céleste", Celestial Mechanics, a description of the workings of solar system based on mathematics rather than on astronomical tables. In it, he translated and expanded the geometrical study of solar mechanics used by Newton to one based on calculus.

A copy of the work was presented to Napoleon who is reported to have asked why there was no mention of God in the study, to which Laplace is alleged to have replied "Je n'avais pas besoin de cette hypothèse-là". ("I had no need of that hypothesis.").

Laplace also developed the foundations of probability theory which he published in 1812 as "Théorie Analytique des Probabilités". Prior to that, probability theory was solely concerned with developing a mathematical analysis of games of chance as exemplified by Pascal. Laplace applied the theory to the analysis of many practical problems in the social, medical, and juridical fields as well as in the physical sciences including mortality, actuarial mathematics, insurance risks, the theory of errors, statistical mechanics and the drawing of statistical inferences.

In 1799 Laplace was appointed by Napoleon as Minister of the Interior but he was removed after only six weeks "because he brought the spirit of the infinitely small into the government".

1784 Cavendish demonstrated that water is produced when Hydrogen burns in air, thus proving that water is a compound of two gases and not an element and overturning over two thousand years of conventional wisdom.

1784 Henry Cort, owner of a forge in Portsmouth supplying iron products to the British Navy, developed puddling, a method of converting cast pig iron into low carbon content wrought iron to improve its quality and strength. Molten pig iron was heated in a puddling furnace and stirred manually with long rods by "puddlers" to promote oxidation or burning of the remaining carbon in the iron by the air to form CO2 which was released. After the metal cooled and solidified, it was worked with a forge hammer and could be rolled into sheets, bars or rails. This was the method used to produce the wrought iron used in the first ironclad warships. It was also used for the small scale production of low-carbon steels for swords, knives and weapons.

See also Iron and Steel Making

1784 King Louis XVI of France set up a Royal Commission to evaluate the claims by German healer and specialist in diseases of the wealthy, Franz Anton Mesmer who had achieved international notoriety with his theory animal magnetism and its supposed therapeutic powers. Members of the committee included Benjamin Franklin, Antoine Lavoisier and the physician Joseph-Ignace Guillotin, inventor of the Guillotine which was later used to remove the heads of both Lavoisier and the King. Mesmer had claimed extraordinary powers to cure patients of various ailments by using magnets. He also claimed to be able to magnetise virtually anything including paper, wood, leather, water, even the patients themselves and that he himself was a source of animal magnetism, a magnetic personality. His clients were mainly aristocratic women many of whom reported pleasurable experiences as Mesmer moved his hands around their bodies to align the flow of magnetic fluid while they were in a trance. Mesmer was a patron of the composer Wolfgang Amadeus Mozart who included a scene in which Mesmer's magnets were used to revive victims of poisoning in the opera "Cosi fan tutte". The committee however concluded that all Mesmer's observed effects could be attributed to the power of suggestion and he was denounced as a fraud. He did however keep his head (the French revolution was still four years away) and his name lives on as hypnotists mesmerise their subjects.

Guillotin by the way was not a revolutionary. As a physician he merely proposed the guillotine as a more humane method of execution rather than hacking away with a sword.

1785 French military engineer and physicist, Charles-Augustin de Coulomb published the correct quantitative description of the force between electrical charges, the Inverse Square Law, which he verified using a sensitive torsion balance which he had invented in 1777. He showed that the electrical charge is on the surface of the charged body. Coulomb's Law was the first quantitative law in the history of electricity.

Coulomb also founded the science of friction.

The unit of charge is named the Coulomb in his honour.

1786 Luigi Galvani professor of anatomy at Bologna Academy of Science in Italy discovered that two dissimilar metals applied to the leg of a dead frog would make it twitch although he believed that the source of the electricity was in the frog. He was quite possibly influenced in his conclusions by the knowledge of Walsh's experiments with electric fish. He found copper and zinc to be very effective in making the muscles twitch. Could it be animal electricity?.

Galvani, a religious man, believed without question that the electricity was a God given property of the animal and that electrical fluid (electricity) was the "spark of life". On the other hand, his friend Volta more of a showman, influenced by "the enlightenment" and "rational thought" questioned religious dogma and believed that the electricity was man made and came from the metals. For many years a debate raged until it was eventually resolved by Volta's invention of the Voltaic pile. In the meantime Galvani lost his job for refusing to swear allegiance to Napoleon's Cisalpine Republic whereas Volta attempted to accommodate Napoleon and prospered under his rule. Sadly Galvani died in poverty in 1798 without knowing the outcome of the debate.

Galvani's experiments with frogs were repeated on a human specimen in 1803 by his nephew Giovani Aldini at the Royal College of Physicians in London, this time with a battery. He used the corpse of George Forster a convicted murderer, who had just been hanged, to demonstrate the phenomenon called Galvinism. He touched a pair of conducting rods, linked to a large voltaic pile, to various parts of Forster's body causing it to have spasms. When one rod was placed at the top of the spine and the other inserted into the rectum, the whole body convulsed and appeared to sit upright giving the illusion that electricity had the power of resurrection.

It is claimed that Aldini's demonstration was the inspiration for Mary Shelley's 1818 novel "Frankenstein" about a scientist who uses electricity to bring an inanimate body to life with disastrous consequences.

1787 Experiments by French physicist and chemist Jacques Charles (later continued by Joseph Louis Gay-Lussac) revealed that:

  • All gases expand or contract at the same rate with changes in temperature provided the pressure is unchanged.
  • The pressure of a fixed mass and fixed volume of a gas is directly proportional to the gas's temperature. Discovered by Gay Lussac in 1802, the effect (law) is now named after him.
  • The change in volume amounts to 1/273 of the original volume at 0°C for each Celsius degree the temperature is changed.

This work provided the inspiration for Kelvin's subsequent theories on thermodynamics.

Charles' Law and Gay Lussac's Law (1802) together with Boyle's Law (1662) and Avogadro's Law (1811) are known collectively as the Gas Laws.

Combining these laws into one relationship we get the Ideal Gas Law:

pV = nRT


p is the pressure

V is the volume

n is the number of moles associated with the volume

R is the universal gas constant

T is the temperature in degrees Kelvin

Note that P*V has the dimensions of Force*Distance and thus represents a measure of the energy in the system and the relationship implies that the energy in the system is proportional to the temperature and, for a given temperature and a given quantity of gas, the energy is constant no matter how the pressure and volume vary.

In his spare time, Charles was an enthusiastic balloonist making several ascents and improving ballooning equipment.

1787 John Fitch a skilled metalworker and American patriot, after being imprisoned by the British in the Revolutionary war, turned his energy to harnessing steam power. Early steam engines were too big and heavy to be used in practical road vehicles, however this restriction did not apply to large marine vessels which were big enough to accommodate them. Fitch built a 45 foot (13.7 M) steamboat propelled by six paddles on either side like an Indian canoe, following up in 1788 with a 60 foot (18 M) paddle wheeler with stern paddles which moved like ducks' feet. In 1790 he launched an even larger boat, with improved paddle wheels more like modern designs, which operated a regular passengers service on the Delaware river but with few passengers it operated at a loss and his financial backers pulled out. He obtained a French patent for his invention in 1795 but attempts to build a business in Europe also failed.

Undue credit for the invention of the steamboat is often given to Robert Fulton who repeated Fitch's work twenty years later, building and successfully operating steamboats on the Hudson River.

See more about Steam Engines


1789 French chemist Antoine Laurent Lavoisier considered to be the founder of modern chemical science, published Traité Élémentaire de Chimie or "Elementary Treatise of Chemistry", the first modern chemistry textbook. In it he presented a unified view of new theories of chemistry and a clear statement of the Law of Conservation of Mass which he had established in 1772. In addition, he defined elements as substances which could not be broken down further and listed all known elements at the time including oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulphur. As intended, it did for chemistry what Newton's Principia had done for physics one hundred years earlier.

Lavoisier was the first to apply rigorous scientific method to chemistry. He carried out his experiments on chemical reactions with meticulous precision devising closed systems to ensure that all the products of the reactions were measured and accounted for. He thus demolished the wild ideas of the alchemists as well as the Greek concept of four elements, earth, air, fire and water which had been accepted for over 2000 years.

Lavoisier had a wide range of interests and a prodigious appetite for work and funded his experiments from his part time job as a tax collector. He was aided in his scientific endeavours by his wife Marie-Anne Pierrette Paulze, whom he had married when she was only thirteen years old. The couple were at the centre of a Parisian social life, but in 1794 Lavoisier's tax collecting activities fell foul of France's revolutionary mob and he was Guillotined during the Reign of Terror. An appeal to spare his life was cut short by the judge with the words "The Republic has no need of scientists".

Afterwards the French mathematician Joseph-Louis Lagrange said "It took them only an instant to cut off that head, and a hundred years may not produce another like it".

See also Lavoisier's relationship with Rumford

1790 The first patent laws established un the USA by a group led by Thomas Jefferson. Until US Independence, when Intellectual Property Rights were protected by the American Constitution, the King of England officially owned the intellectual property created by the colonists. Patents had however been issued by the colonial governments and were protected by British law.

The first US patent was granted to Samuel Hopkins of Vermont for a new method of making Potash.

1791 German chemist and mathematician Jeremias Benjamin Richter attempted to prove that chemistry could be explained by mathematical relationships. He showed that such a relationship applied when acids and bases neutralize to produce salts they do so in fixed proportions. Thus he was the first to establish the basis of quantitative chemical analysis which he named stoichiometry. He died of tuberculosis at the age of 45.

1791 English mining engineer John Barber patented a gas turbine engine. His patent, "A Specification of an Engine for using Inflammable Air for the purposes of procuring Motion and facilitating Metallurgical Operations.....and any other Motion that may be required.", outlined the operating principle and thermodynamic cycle of the engine which contained all the essential features of the modern gas turbine. The fuel used was coal gas. Fuel and air were compressed by two separate reciprocating piston pumps, chain driven from the turbine shaft, and then fed into a combustion chamber where the fuel was burned. The expanding combustion gases were then directed through a nozzle onto an impulse turbine wheel driving the output shaft.

Performance was unfortunately limited by the materials technology of the day and losses in the compression stage which reduced the available output power. Barber had a solution to alleviate these problems. He geared a water pump to the output shaft which injected a small stream of cold water into the hot combustion gases to cool the combustion chamber and the impulse wheel. This had the dual benefit in that the resulting steam increased the density of the jet impinging on the turbine wheel and thus increased the power output.

He also envisaged using the output jet from the engine to power a boat through water.

1792 Scottish engineer and inventor William Murdoch employed by Boulton and Watt to supervise their pumping engines in Cornwall was the first to make practical use of coal gas. By heating coal in a closed iron retort with a hollow pipe attached he produced a steady stream of coal gas for lighting his house.

Coal gas was one of the byproducts of pyrolysis or the destructive distillation of coal was already used to produce coke which was used in metallurgical processes to extract metals from their ores. At first the public were not interested in Murdoch's application due to health and safety fears and his employers discouraged him from patenting the idea so he left the company in 1797 to exploit it himself. When others showed interest in commercialising coal gas Boulton and Watt realised their mistake and Murdoch was invited back the following year. Boulton and Watt subsequently became major players in the gas business selling integrated illumination systems with their own self contained gas generators. Coal gas lighting was eventually patented in 1804 by German inventor Friedrich Albrecht Winzer (Frederick Albert Winsor) who pioneered the installation in Britain of public gas lighting and gas distribution systems fed from large central gas works.

The production of coke and coal gas left huge residues of coal tar which were initially regarded as mostly waste. It was another 50 years before Perkin showed how considerable value could be extracted from this waste.

1794 American law graduate and inventor Eli Whitney patented the cotton gin ("gin" derived form "engine") which automated the process of separating cottonseed from raw cotton fibres. It was about 50 times faster than the previous method of processing the cotton by hand and revolutionised cotton production in the United States, work which had formerly been done by slaves. His cotton engine consisted of a box in which was mounted a revolving cylinder with spiked teeth, or wire hooks, which pulled the cotton fibre through small slotted openings thus separating the seeds from the lint. A separate rotating brush, operated from the main drum via a belt and pulleys, removed the loose fibrous cotton lint from the projecting spikes or hooks. Early devices were powered by a hand crank but these were soon replaced by larger horse-drawn or water powered machines.

Paradoxically, the introduction of the cotton gin as a labour saving device did not reduce the demand for slave labour. Because cotton could be produced much more cheaply, the demand increased, more cotton was planted and cotton replaced tobacco and indigo as cash crops so that many more slaves were required to grow the cotton and harvest the fields. Some people claim that by increasing the demand for slave labour, the introduction of the cotton gin was one of the causes of the American Civil War.

Despite the success of the cotton gin, it was quickly copied many times over and Whitney spent much of his money on legal battles over patent infringements.

In 1798 Whitney also pioneered the use of interchangeable parts in the production of muskets which proved to be more commercially successful.

1795 The hydraulic press used for lifting heavy weights or for the presses used in metal forming was patented by English engineer Joseph Bramah. The principle on which it depends was first outlined by Pascal 150 years earlier but not turned into practical products.

1797 Young Prussian noble Alexander von Humboldt published a book outlining his theories about Galvanic electricity and his experiments to support them. He believed that the electricity came from the muscle and was intensified by the electrodes and he carried out experiments on plants and animals to prove it. He also carried out numerous experiments on himself to gather more data using a Leyden jar to inflict severe shocks on his body until it was badly lacerated and scarred. He was mortified three years later when his theories were proved completely wrong by Volta and turned his attention instead to geology, botany and exploration in all of which he found international fame but no fortune.

1797 English engineer Henry Maudslay introduced the precision screw-cutting lathe. Although lathes had been in use from before 3000 B.C. when the Egyptians used the bow lathe for wood turning, Maudslay's lathe was the first true ancestor of the modern machine tools industry. He raised the standards of precision, fits, finishes and metrology and invented the first bench micrometer capable of measuring to one ten thousandth of an inch which he called the "Lord Chancellor" because it resolved disputes about the accuracy of workmanship in his factory.

Maudslay's pupils included Scottish engineer James Naysmith who designed and made heavy machine tools, including the shaper and the steam hammer, for the ship building and railway industries and English engineer Joseph Whitworth who worked on Babbage's Difference Engine and later introduced the Whitworth standard system for screw-cutting threads which was first adopted by the railways and the Woolwich Arsenal and then became an industry standard enabling interchangeability of components and production automation. See also Whitney - next.

1798 In an age when mechanical devices were individually made and laboriously fitted by hand, American engineer Eli Whitney pioneered the concept of interchangeable parts in the USA, using precision manufacturing made possible by more accurate machine tools just becoming available. Prior to that, if a part failed, a replacement part had to be made and fitted individually creating major problems and losses in battlefield conditions. Whitney's methods also reduced the skill levels needed to manufacture and assemble the parts enabling him to take on a contract to supply 10,000 muskets in two years to the US government. Whitney also built a rudimentary milling machine in 1818 for use in firearms manufacturing, but the universal milling machine as we would recognise it today was invented by American engineer Joseph Rogers Brown in 1862. Brown's machine was able to cut the flutes in twist drills. Since the introduction of twist drills in the 1820's these flutes had been filed by hand.

In 1794 Whitney also invented the cotton gin which revolutionised the processing of raw cotton.

1799 Count Rumford, man of science, inventor, administrator, philanthropist, self publicist and scoundrel, born Benjamin Thompson in the USA, founded The Royal Institution in London to promote and disseminate the new found knowledge of the industrial revolution. Its first director was a well connected, glamorous young Cornish chemist, Humphry Davy. Davy was a great showman, but did not consider "common mechanics" worthy of his brilliance, so the Institution rapidly evolved to presenting lectures for the wealthy, who paid to attend. In Rumford's original plan, there had been a back door through which the poor could access a balcony to hear the lectures from a distance for free. Davy had it bricked up. The Institution did, however, perform a very valuable function in that it was a subsidised science lab, one of the very few in the world, which enabled scientists of the day, such as Michael Faraday, to make many important discoveries.

Rumford was a colourful character, like fellow American Benjamin Franklin, a man of many talents. Raised in pre-Revolutionary New England, at the age of 19 he married a wealthy 31-year-old widow and he took up spying on the colonies for the British but left for England in 1776 when he was found out, deserting his wife and daughter. At first he worked in the British foreign office as undersecretary for Colonial Affairs and was knighted by George III after a stint in the army fighting on the British side in the American War of Independence. He moved on to Munich where he carried out public and military works for the Elector of Bavaria being rewarded in 1792 with the title Count of the Holy Roman Empire. Among his inventions were the drip coffee pot and thermal underwear.

His interest in field artillery led him to study both the boring and firing of cannons. Out of this work he saw that mechanical power could be converted to heat -- that there was a direct equivalence between thermal energy and mechanical work. Heat was produced by friction in unlimited quantities so long as the work continued. It could therefore not be a fluid called a Caloric flowing in and out of a substance as his adversary, the noted French chemist, Antoine Lavoisier, had proposed, since the fluid would have a finite quantity.

After Lavoisier's death Rumford started a four year affair with his wealthy, young widow, however after a short unhappy marriage they divorced with Rumford remarking that Lavoisier was lucky to have been guillotined. Rumford lived out the rest of his life in Lavoisier's former house in France engaged in scientific studies and it is claimed that he was paid by the French for spying on the British.

1799 English aristocrat, engineer and polymath, George Cayley, one hundred years before the Wright brothers, outlined the concept of the modern aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control. He was the first to understand the underlying principles and to identify the four basic aerodynamic forces of flight, namely weight, lift, drag, and thrust, which act on any flying vehicle.

Unfortunately there would be no suitable power sources available for many years to realise such a design, but he applied his theories to the design of gliders and made the first successful glider to carry a human being.

Throughout time, countless philosophers and experimenters had been fascinated by the flight of birds and the shape of their wings, however Cayley was the first to undertake a methodical study of the shape and cross section of wings and it is to him that we owe the idea of the curved aerofoils used in modern aircraft designs.

His theories and designs were based on models he had tested on a "whirling-arm apparatus" he had built to simulate airflow over the wings and to measure the drag on objects at different speeds and angles of attack. It had the same functions as a modern wind tunnel but instead, it was based on an earlier design by Smeaton which enabled models to be passed at high speed in a circular path through the still air. Balance springs were used to measure the forces on the model.

From his researches, he showed that a curved aerofoil produces significantly more lift than a simple flat plate. He also identified the need for aerodynamic controls to maintain stability in flight and was the first to design an elevator and a rudder for that purpose.

Cayley's paper "On Aerial Navigation", published in 1810, was the first scientific work about aviation and the theory of flight and marked the birth of the science of aeronautics.

See more about Aerofoils and Theories of Flight.

Cayley is remembered for his ground breaking work on aerodynamics and aeronautics however he was also a prolific inventor and has been called by some "the English Leonardo" though there are other candidates for this accolade (see Hooke) and some of his sketches for ornithopters and vertical takeoff aircraft are reminiscent of Leonardo's drawings. The following are some of his other activities and inventions.

  • In 1800 he presented to parliament a comprehensive plan he had devised for land reclamation and flood control.
  • His early work between 1804 and 1805 centred on ballistics. He designed artillery shells with fins which imparted a rotating movement of the shell about the direction of travel which in turn increased their range and later he introduced shells with explosive caps which increased their destructive power.
  • In 1807 he published a paper on the Hot Air Engine and started a series of experiments to improve its performance. The ideas were picked up by Robert Stirling who made his own improvements and patented the engine in 1816.
  • Also in 1807 he described a reciprocating engine fuelled by gunpowder. It consisted of two pistons connected in line and connected to one of them was an external tube into which a fixed amount of gunpowder was automatically fed with each cycle. A constantly burning flame at the end of the tube ignited the gunpowder and the gas generated, together with the expansion of the air in the second piston due to the heat of the explosion, forced the pistons to the top of their stroke. The pistons were returned to the start position by means of a stout bowspring. The engine did not produce rotary motion. There is no record of it having been built and the idea was abandoned as being too unreliable.
  • In his quest for a lightweight undercarriage for his gliders, Cayley turned his attention in 1808 to the wheels. For centuries wheels had been made with stout wooden spokes to support the weight of the vehicle exerted through the axle bearing down on the spokes. The spokes themselves had to be strong enough to support this compressive load so that wheels were generally very heavy. Cayley turned the problem on its head. Instead of spokes in compression, he designed a wheel in which the axle was suspended from the rim of the wheel by slender wire spokes in tension. The magnitude of the force was the same but a wire under tension can accommodate much higher forces than a shaft of wood under compression. This lightweight wheel was the forerunner of the modern bicycle wheel. Cayley thus re-invented the wheel.
  • Another of his inventions was the caterpillar track which he patented in 1825 shortly after Stephenson ran his first railway service, now used in tanks and earth moving equipment. It was an attempt to free steam trains from their dependence on the fixed itinerary determined by the railway lines so that they could deviate down untracked roads. He called it the "Universal Railway".
  • He experimented with light, heat and electricity and in 1828 he estimated absolute zero temperature to be -480°F about 11.44°C lower than the 273.15°C confirmed by Kelvin in 1848.
  • Cayley gave a lot of attention to the safety on the new railway systems crisscrossing the country. His first idea, published in 1831, after the first fatal railway accident at the 1829 Rainhill trials when the unfortunate William Huskisson was run over by Stephenson's Rocket, was a "Cow Catcher" though this was never introduced in Britain. At the same time he examined operating procedures and recommended that speed limits and driver training should be introduced. He also proposed the introduction of automatic braking systems and designed a braking system for that purpose. To reduce injuries in case of accidents he designed a compressed air buffer truck to be incorporated into the trains and recommended that passengers should wear seat belts and that the walls of the carriages should be covered with padded cushions (air bags?). In 1841 he also proposed new operating procedures coupled with a method of automatic signalling he designed to ensure that no two trains could ever meet on the same tracks.
  • He also campaigned for the compulsory introduction of self-righting lifeboats following designs by William Wouldhave in 1789 and earlier proposals in 1785 by Lionel Lukin.
  • Following a fire at London's Covent Garden Theatre in 1808 which twenty three firemen were killed, Cayley proposed the design of a new theatre which incorporated many of the features which are included in modern fire regulations such as safety curtains, large outward opening doors, a large reservoir of water and a pumps to direct it onto the fire. His proposal was not accepted and 47 years later its replacement, built in the classical Athenian style, was burnt to the ground.
  • Prompted by a friend who had lost his hand, in 1845 he designed a prosthetic hand with spring movements which enabled it to grip and pick up objects. At the time there were few concessions by the government or society to disabled people and amputees merely had a hook in place of their hand. Cayley's idea was considered too expensive and fell on stony ground.
  • In his spare time he was also a Member of Parliament, representing Scarborough.

Cayley had strong views that people should not profit in any way from human suffering and did not patent any of the ideas relating to safety or disability.


VOLTA Inventor of the Battery

Alessandro Volta

The man who started it all.

Voltaic Pile - The First Battery

Volta's Pile

Alessandro Volta of the University of Pavia, Italy, describes the principle of the electrochemical battery in a letter to the Royal Society in London. The first device to produce continuous electric current. He had been interested in electrical phenomena since 1763 and in 1775 he had made his own electrophorus for carrying out his experiments. He was a friend of Galvani but disagreed with him about the nature of electricity. Galvani's experiments with frogs had led him to believe that the source of the electricity was the frog, however Volta sought to prove that the electricity came from outside of the frog, in his case from the dissimilar metals used to probe the specimen.

His "Voltaic Pile" was initially presented in 1800 as an "artificial electric organ" to demonstrate that the electricity was independent of the frog. It was constructed from pairs of dissimilar metals zinc and silver separated by a fibrous diaphragm (Cardboard?) moistened with sodium hydroxide or brine and provided the world's first continuous electric current. The pile produced a voltage of between one and two volts. To produce a higher voltages he connected several piles together with metal strips to form a "battery". He was the first to understand the importance of "closing the circuit".

Volta's invention caused great excitement at the time and he gave many demonstrations including drawing sparks from the pile, melting a steel wire (the first fuse?), discharging an electric pistol and decomposing water into its elements. Though little more than a curiosity at first, the ability to deliver electric energy on demand was an important development contributing to the Industrial Revolution.

Napoleon was particularly impressed, insisting on helping with the demonstrations when he was present and showering Volta with honours despite the fact that France and Italy were initially at war with each other. The unit of electric potential was named the Volt in his honour.

After the invention of the battery, Volta was awarded a pension by Napoleon and he began to devote more of his time to politics, holding various public offices. He retired in 1819 and died in 1827 and although the battery was a sensation in scientific circles and giving impetus to an intensification of scientific investigation and discovery throughout the nineteenth century, surprisingly Volta himself never participated in these opportunities.

1800 English scientists, William Nicholson and Anthony Carlisle, experimenting with Volta's chemical battery, accidentally discovered electrolysis, the process in which an electric current produces a chemical reaction, and initiated the science of electrochemistry. (A discovery like many others claimed by Humphry Davy though he did actually do original work at a later date on electrolysis).

This new technique, made possible by the availability of the constant electric current provided by the new found batteries, enabled many compounds to be separated into their constituent elements and led to the discovery and isolation of many previously unknown chemical elements. Electrolysis, "loosening with electricity", thus became widely used by scientific experimenters.

1800 German born, English astronomer, Frederick William Herschel in an experiment to measure the heat content of the various colours in the visible light spectrum, placed a thermometer in the spectral patches of coloured light. He discovered that not only did the temperature rise as he approached the low frequency, red end of the spectrum, but the temperature continued to rise beyond the red colour even though there were no visible light rays there. The conclusion was that the energy spectrum of the Sun's light was wider than that visible to the naked eye. The long wave radiation below the red end of the spectrum was named infra red radiation.

1801 After Herschel's discovery of radiation below the red end of the light spectrum (See above), German physicist, Johann Wilhelm Ritter, explored the short wave region above the violet end of the spectrum. Using the phenomenon discovered by Scheele, that the colourless salt, Silver chloride is turned black by light rays from the violet end of the spectrum, he showed that higher frequency rays from above the violet radiation also caused strong blackening of the silver salt. This higher frequency energy was named ultra violet radiation.

1801 French silk-weaver, Joseph-Marie Jacquard invented an automatic loom using punched cards to control the weaving of the patterns in the fabrics. This was not the earliest implementation of a stored program and the use of punched cards programmed to control a manufacturing process as is often claimed. That honour goes to Bouchon starting in 75 years earlier and improved by Falcon in 1728 and eventually refined by de Vaucanson in 1744. Jacquard presented his invention in Paris in 1804, and was awarded a medal and patent for his design by the French government who consequently claimed the loom to be public property, paying Jacquard a small royalty and a pension. Its introduction caused riots in the streets by workers fearing for their jobs.

Despite the loom's fame, Jacquard's principles of programmed control and automation were not applied to any other manufacturing process for another 145 years when Parsons produced the first numerically controlled machine tools.

1801 Frenchman Nicholas Gautherot observed that when a current from a voltaic battery was sent between two Copper plates immersed in Sulphuric acid, for a short period afterwards the copper plates could drive a current back in the opposite direction. He had inadvertently discovered the rechargeable battery but did not realise its significance. Sixty years later Planté repeated the experiment with Lead plates and the Lead Acid battery was born.

1802 English chemist Dr William Cruikshank designed the first battery capable of mass production. A flooded cell battery constructed from sheets of copper and zinc in a wooden box filled with brine or acid.

Cruikshank also discovered the electrodeposition of copper on the cathodes of copper based electrolytic cells and was able to extract metals from their solutions, the basis modern metal refining and of electroplating, but it was not until 1840 that the commercial potential of the plating process was realised by the Elkingtons.

1802 British chemist William Hyde Wollaston discovered dark lines in the optical spectrum of sunlight which were subsequently investigated in more detail and catalogued by Fraunhofer in 1814.

Wollaston also investigated the optical properties of quartz crystals and discovered that they rotate the plane of polarisation of a linearly polarised light beam travelling along the crystal optic axis. He applied this property in his invention of the Wollaston prism in which he used two crystal prisms mounted back to back to separate randomly polarised or unpolarised light into two orthogonal, linearly polarized beams which exit the prism in diverging directions determined by the wavelength of the light and the angle and length of the prism. Wollaston prisms are used in polarimeters and also in Compact Disc player optics.

Wollaston was also active as a chemist. He discovered the element Palladium in 1803 and Rhodium the following year and in 1816 he invented improvements to the battery. His attempts to invent an electric motor were less successful however bringing him into conflict with Michael Faraday


1803 Ritter first demonstrated the elements of a rechargeable battery made from layered discs of copper and cardboard soaked in brine. Unfortunately there was no practical way to recharge it other than from a Voltaic Pile and for many years they remained a laboratory curiosity until someone invented a charger. Ritter was one of the first to identify the phenomenon of polarisation in acidic cells. He also repeated Galvani's "frog" experiments with progressively higher voltages on his own body. This was probably the cause of his untimely death at the age of 33.

1803 John Dalton a Quaker school teacher working in Manchester resurrects the Greek Democritus' atomic theory that every element is made up from tiny identical particles called atoms, each with a characteristic mass, which can neither be created or destroyed. Dalton showed that elements combine in definite proportions and developed the first list of atomic weights which he first published in 1803 at the Manchester Literary and Philosophical Society and at greater length in book form in 1808.

In 1801 Dalton also formulated the empirical Law of Partial Pressures, now considered to be one of the Gas laws. It states that in a mixture of ideal gases the total pressure is equal to the sum of the partial pressures of each individual component in a gas mixture. In other words, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. Besides its concentration, the partial pressure of the gas in a gas mixture has a major effect in determining its physical and chemical reaction rates.

For an example of the application of the Law of Partial Pressures see Refrigeration.

1804 The Electric telegraph one of the first attempted applications of the new electric battery technology was proposed by Catalan scientist Francisco Salvá. One wire was used for each letter of the alphabet and each number. The presence of a signal was indicated by a stream of hydrogen bubbles when the telegraph wire was immersed in acid. The system had a range of one kilometer.

1804 Mining engineer Richard Trevithick, known as the Cornish Giant, built the Pen-y-Darren steam engine, the first locomotive to run on flanged cast iron rails. It hauled 10 tons of iron and 70 men on 5 wagons from Pen-y-Darren to Abercynon in Wales on the Merthyr Tydfil tramroad, normally used for horse drawn traffic, at a speed of 2.4 mph (3.9 km/h) thus disproving the commonly held theory that using smooth driving wheels on smooth rails would not allow sufficient traction for pulling heavy loads. (See Trevithick's Pen-y-Darren Locomotive)

Trevithick's locomotive incorporated several radical innovations. He did not use the steam engine with a separate condenser recently invented by James Watt, the most efficient technology of the day, partly to circumvent the onerous conditions of the Boulton and Watt patent, but also because Watt's engines were too heavy and bulky for mobile use. Instead, to achieve greater efficiencies in a smaller, lighter engine he used a high pressure system with the power stroke being produced by high pressure steam on the piston rather than atmospheric pressure as in Watt's engine.

Higher pressure systems exposed weaknesses in current boiler designs which Trevithick overcame by using a cylindrical construction which was inherently stronger and could withstand much higher pressures and this became the pattern for all subsequent steam engines.

He did however use one of Watt's other innovations, the double acting piston, in which a sliding valve coupled to the piston enabled the steam to be applied alternately to each surface of the piston providing a power stroke in both the forward and back motions of the piston. (See Double Acting Piston).

To improve combustion efficiency he replaced the conventional method of producing steam in which an external flame was used to heat the water in a separate kettle or boiler, by using instead, a return flue boiler in which a U shaped, internal fire tube flue passed through the water boiler and bent back on itself to increase the surface area heating the water. Efficiency was further improved by directing the exhaust steam from the driving piston up the chimney to increase the air draft through the boiler fire. Known as the "blast pipe", this latter steam release is what gave steam engines their characteristic puffing sound.

Together, these innovations provided a 10 fold increase in efficiency over Watt's engine and all of these ideas were subsequently used by George Stephenson on his Rocket locomotive.

Converting the reciprocating motion of the piston to rotary motion for driving the wheels was however was the Achilles heal of this particular engine being overly complicated. The single horizontal piston was located centrally above the boiler and the linear motion of the piston was transferred through a connecting beam perpendicular to the piston to two connecting rods or cranks, one on either side of the boiler. On one side the crank drove a large flywheel to smooth the motion and on the opposite side of the boiler the crank turned a spur gear mounted on the same shaft as the flywheel. The drive from this input gear was transferred via a large intermediate gear to spur gears mounted on the two drive wheels on the same side of the engine. There was no drive to the two wheels on the opposite side of the vehicle.

Trevithick was a larger than life character, bursting with ingenious ideas but unsuccessful in converting them into profitable business. Between 1811 and 1827 he spent time working on steam engines used in Peruvian silver mines and exploring South America on his way back. After a perilous journey he arrived penniless in Cartagena in Colombia where by amazing coincidence he met Robert Stephenson, whom he had known as a child, who paid his passage home.

See more about Steam Engines


1805 Italian chemist Luigi Valentino Brugnatelli, friend of Volta demonstrated electroplating by coating a silver medal with gold. He made the medal the cathode in a solution of a salt of gold, and used a plate of gold for the anode. Current was supplied by a Voltaic pile. Brugnatelli's work was however rebuffed by Napoleon Bonaparte which discouraged him from continuing his work on electroplating.

The process later became widely used for rust proofing and for providing decorative coatings on cheaper metals. Gold plating is used extensively today in the electronics industry to provide low resistance, hard wearing, corrosion proof connectors.

1807 English physician, physicist, and Egyptologist Thomas Young introduced a measure of the stiffness or elasticity of a material, now called Young's Modulus which relates the deformation of a solid to the force applied. Also called the Modulus of elasticity it can be thought of as the spring constant for solids. Young's modulus is a fundamental property of the material. It enables Hooke's spring constant, and thus the energy stored in the spring to be calculated from a knowledge of the elasticity of the spring material.

Young was the first to assign the term kinetic energy to the quantity ½MV2 and to define work done, as force X distance which is also equivalent to energy, an extension to Newton's Laws but surprisingly taking 140 years to emerge. More surprising still is that it was another 44 years before the concept of potential energy was proposed.

He also did valuable work on optical theory and in 1801 he devised the Double slit interference experiment which verified the wave nature of light.

Young is considered by some to be the last person to know everything there was to know. (Not the only candidate to this fame). He was a child prodigy and had read through the Bible twice by the age of four and was reading and writing Latin at six. By the time he was 14 he had a knowledge of at least five languages, and eventually his repertoire grew to 12. He practiced medicine until the work load clashed with his other interests, and among his many accomplishments he translated the inscriptions on the Rosetta Stone which was they key which enabled hieroglyphics to be deciphered.

1807 Humphry Davy constructed the largest battery ever built at the time, with over 250 cells, and passed a strong electric current through solutions of various compounds suspected of containing undiscovered elements isolating Potassium and Sodium by this electrolytic method, followed in 1808 with the isolation of Calcium, Strontium, Barium, and Magnesium. The following year Davy used his batteries to create an arc lamp.

In 1810 Davy was credited with the isolation of Chlorine, already discovered by Scheele in 1773.

In 1813 Davy wrote to the Royal Society stating that he had identified a new element which he called Iodine, four days after a similar announcement by Gay-Lussac. The element had in fact been isolated in 1811 from the ashes of burnt seaweed by Bernard Courtois, the son of a French saltpetre manufacturer, who had passed samples to Gay-Lussac and Ampère for investigation. Ampère in turn passed a sample to Davy. Although Courtois discovery was not disputed, both Davy and Gay-Lussac both claimed credit for identifying the element.

1807 Robert Fulton a prolific American inventor is most remembered for building the Claremont steamboat which successfully plied the Hudson River in 1807 steaming between New York and Albany in 32 hours with an average speed of 5 miles per hour. He had earlier built a steamboat based on John Fitch's design which operated on the Seine in Paris in 1803. Where Fitch succeeded technically but failed commercially, Fulton made a commercial success of Fitch's technology and is unduly remembered as the inventor of the steamboat.

See more about Steam Engines


1807 As a result of his studies on heat propagation, French mathematician Baron Jean Baptiste Joseph Fourier presented a paper to the Institut de France on the use of simple sinusoids to represent temperature distributions. The paper also claimed that any continuous periodic signal could be represented as the sum of properly chosen sinusoidal waves.

For the previous fifty years the great mathematicians of the day had sought equations to describe the vibration of a taut string anchored at both ends as well as the related problem of the propagation of sound through an elastic medium. French mathematicians Jean d'Alembert and Joseph-Louis Lagrange and Swiss Leonhard Euler and Daniel Bernoulli had already proposed combinations of sinusoids to represent these physical phenomena and in Germany, Carl Friedrich Gauss had also been working on similar ways to analyse mechanical oscillations (see below). Whereas their theories applied to particular situations, Fourier's claim was controversial in that it extended the theory to any continuous periodic waveform.

Among the reviewers of Fourier's paper were Lagrange, Adrien-Marie Legendre and Pierre Simon de Laplace, some of history's most famous mathematicians. While Laplace and the other reviewers voted to publish the paper, Lagrange demurred, insisting that signals with abrupt transitions or "corners", such as square waves could not be represented by smooth sinusoids. The Institut de France bowed to the prestige of Lagrange, and rejected Fourier's work. It was only after Lagrange died that the paper was finally published, some 15 years later.

When Fourier's paper was eventually published in 1822, it was restated and expanded as "Theorie Analytique de la Chaleur", the mathematical theory of heat conduction. The study made important breakthroughs in two areas. In the study of heat flow, Fourier showed that the rate of heat transfer is proportional to the temperature gradient, a new concept at the time, now known as Fourier's Law.

Of greater importance however were the mathematical techniques Fourier developed to calculate the heat flow in unusually shaped objects. He provided the mathematical proof to support his 1807 claim that any repetitive waveform can be approximated by a series of sine and cosine functions, the coefficients of which we now call the Fourier Series. These coefficients represent the magnitudes of the different frequency components which make up the original signal. When the sine and cosine waves of the appropriate frequencies are multiplied by their corresponding coefficients and then added together, the original signal waveform is exactly reconstructed. Thus complex functions such as differential equations can be converted into simpler trigonometric terms which are easier to handle mathematically by calculus or other methods.

This mathematical technique is known as the Fourier transform and its application to an electrical signal or mechanical wave is analogous to the splitting or "dispersion" of a light beam by a prism into the familiar coloured optical spectrum of the light source. An optical spectrum consists of bands of colour corresponding to the various wavelengths (and hence different frequencies) of light waves emitted by the source. In the same way, applying the Fourier transform to an electrical signal separates it into its spectrum of different frequency components, often called harmonics, which makes it very useful in electrical engineering applications.

Fourier showed that the harmonic content of a square wave can be represented by an infinite series of harmonics approximated by the expression:


f(t) =       1 sin (nωt)    Where ω is the pulse repetition frequency.

                 n=1   n

High frequency harmonics are required to construct the sharp pulse transitions of the square wave so that a high bandwidth is required to transmit a pulsed waveform without distortion. In practice, 10 to 15 times the fundamental frequency of the bit rate provides enough bandwidth to transmit a recognisable square wave. Thus to transmit a 1 kHz square wave would require a channel bandwidth of at least 10 kHz.

In electrical engineering applications, the Fourier transform takes a time series representation of a complex waveform and converts it into a frequency spectrum. That is, it transforms a function in the time domain into a series in the frequency domain, thus decomposing a waveform into harmonics of different frequencies, a process which was formerly called harmonic analysis.

The Fourier Transform has wide ranging applications in many branches of science and while many contributed to the field, Fourier is honoured for his insight into the practical usefulness of the mathematical techniques involved.

Fourier led an exciting life. He was a supporter of the Revolution in France but opposed the Reign of Terror which followed bringing him into conflict and danger from both sides. In 1798 he accompanied Napoleon on his invasion of Egypt as scientific advisor but was abandoned there when Nelson destroyed the French fleet in the Battle of the Nile. Back in France he later provoked Napoleon's ire by pledging his loyalty to the king after Napoleon's abdication and the fall of Paris to the European coalition forces in 1814. When Napoleon escaped from Elba in 1815 Fourier once more feared for his life. His fears were unfounded however and, despite his disloyalty, Napoleon awarded him a pension but it was never paid since Napoleon was defeated at Waterloo later that year.

As noted above Fourier was not the only one at the time looking for simple solutions to complex mathematical problems. Gauss was trying to calculate the trajectories of the asteroids Pallas and Juno. He knew that they were complex repetitive functions but he only had sampled data of the locations at particular points in time rather than a continuous time varying function from which to construct a mathematical model of the trajectories. Although this was before Fourier's time, like his contemporaries Gauss was aware that the result should be a series of sinusoids, but deriving a transform from sampled or discrete data, rather than from a time varying mathematical function, involves a huge computational task. Such a transform applied to sampled data is now known as a Discrete Fourier Transform (DFT) and can be considered as a digital tool whereas the general Fourier Transform only applies to continuous functions and can be considered as an analogue tool. In 1805 Gauss derived a mathematical short cut for computing the coefficients of his transform. Although he applied it to a specific, rather than a general case, we would recognise Gauss's short cut today as the Fast Fourier Transform (FFT) even though it owed nothing to Fourier.

1808 Prolific Swedish chemist Jöns Jacob Berzelius working at the University of Uppsala in Sweden formulated the Law of Definite Proportions (discovered by Dalton five years earlier and by Richter twelve years before that) which establishes that the elements of inorganic compounds are bound together in definite proportions by weight. Berzelius developed the system of chemical notation we still use today in which the elements were given simple written labels, such as O for oxygen, or Fe for iron, and proportions were noted with numbers. He accurately determined the relative atomic and molecular masses of over 2000 elements and compounds.

1808 Fearing for his life, French civil and marine engineer, architect and royalist, Mark Isambard Brunel, fled from France in 1793 at the start of the "Reign of Terror" which followed the French Revolution after the execution of King Louis XVI. Settling in New York and taking American citizenship, he became the City's Chief Engineer with friends in high places including Alexander Hamilton, one of the U.S. founding fathers. Hearing from one of Hamilton's guests that the Britain's Royal Navy required 100,000 wooden pulley blocks per year as part of their war effort and were looking for a better method of manufacturing them, Brunel saw it as an opportunity to use his engineering talents in a venture too good to miss. Encouraged by Hamilton who saw Brunel's antipathy towards Napoleon as a way to hamper the French, he left the U.S. for England in 1799 with a letter of introduction from Hamilton to Lord Spencer, the British Navy Minister.

After winning a contract to manufacture 60,000 wooden pulley blocks per year, Brunel designed and set up one of the first ever mass production lines which went live in 1808. Instead of one man making a complete pulley Brunel divided the work into a series of simple, short cycle, repetitive tasks and using 43 custom designed, precision machines from Henry Maudslay to carry out the sequential operations in line. In this way he reduced the labour required to do the work from 110 men to 10. A formula which has become an industry standard.

See also Brunel's Thames Tunnel

1809 At a demonstration at the Royal Institution, Davy amazed the attendees by producing an electric arc between two Carbon electrodes - the first electric light and the first demonstration of the useful application of electricity. It was no longer just a curiosity. The demonstration marked the start of a new era, the era of electricity.

Davy is generally credited with inventing the Carbon arc lamp, however a Russian Vasilli V. Petrov had reported this phenomenon in 1803.

In 1816 Davy claimed the credit for the invention of the miner's safety lamp, named the "Davy lamp" in his honour but it was actually similar to a design already demonstrated in 1815 by self taught railway pioneer George Stephenson. The privileged Davy was incensed that he could be upstaged by working class Stephenson.

According to J. D. Bernal's "Science in History" Davy is quoted as saying "The unequal division of property and of labour, the difference of rank and position amongst mankind, are the sources of power in civilized life, its moving causes, and even its very soul."

See also Davy and the Royal Institution


1811 Italian physicist Amadeo Avogadro discovered the concept of molecules. He hypothesized that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. From this hypothesis it followed that relative molecular weights of any two gases are the same as the ratio of the densities of the two gases under the same conditions of temperature and pressure.

This relationship called Avogadro's Hypothesis or Avogadro's Law, now considered as one of the Gas Laws, can be expressed as:

V1 / n1 = V2 / n2

where V is the volume of the gas and n is the number of molecules it contains.

The concept of a mole is a useful measure of the number of "elementary entities" (usually molecules or atoms, but also ions or electrons) contained in a system. See definition of a mole.

The number of "elementary entities" in one mole has been defined as Avogadro's constant or Avogadro's number. It's value was not determined until 1905 by Einstein in his doctorial dissertation.

The basic scheme of atoms and molecules arrived at by Dalton and Avogadro underpins all modern chemistry.

1812 German physician Samuel Thomas von Sömmering increased the range of Salvás (1804) telegraph to three kilometers by using bigger batteries, a method subsequently used with disastrous results on the Transatlantic Telegraph Cable.

1812 Venetian priest and physicist Giuseppe Zamboni developed the first leak proof high voltage "dry" batteries with terminal voltages of over 2000 Volts. They consisted of thousands of small metallic foil discs of tin or an alloy of copper and zinc called "tombacco", separated by paper discs stacked in glass tubes. The technology was not well understood at the time and while Zamboni consciously avoided the use of any conventional corrosive aqueous electrolyte in the cells, hence the name "dry" battery, the electrolyte was actually provided by the humidity in the paper discs and a variety of experimental greasy acidic pulps spread thinly on the foils to minimise polarisation effects. Although the battery voltage was very high, the internal resistance was thousands of megohms so the current drawn from the batteries was about 10-9 amps, limiting the battery's potential applications. One notable application however was a primitive electrostatic clock mechanism in which a pendulum was attracted towards the high voltage terminal of a Zamboni pile by the electrostatic force between the pendulum and the terminal. When the pendulum touched the terminal it acquired the same charge as the terminal and was consequently deflected away from it towards the opposite pole of another similar pile from which, by a similar mechanism it was deflected back again, thus maintaining the oscillation. The current drain or discharge rate of the batteries was so low as to be undetectable with instruments available at the time and it was thought that the pendulum was a "perpetual electromotor". In fact Zamboni primary batteries have been known to last for over 50 years before becoming completely discharged!

1813 French mathematician and physicist Siméon Denis Poisson derived the relationship which relates the electric potential in a static electric field to the charge density which gives rise to it. The resulting electric field is equal to the gradient of the potential. This equation describes the electric fields which drive the flow of charged ions through the electrolyte in a battery.

Poisson published many papers during his lifetime but he is perhaps best remembered for his 1837 paper on the statistical distribution now named after him. The Poisson distribution describes the probability that a random event will occur in a time or space interval under the conditions that the probability of the event occurring is very small, but the number of trials is very large so that the event actually occurs only a small number of times. He used his theory to predict the likelihood of being killed by being kicked by a horse and tested it against French army records over several years of the number of soldiers killed in this way. Apart from analysing accident data, the distribution is fundamental to queuing theory which is used in traffic studies to dimension applications from supermarket checkouts and tollgates to telephone exchanges.

1814 German physicist Joseph von Fraunhofer identified and catalogued a series of 570 dark lines, first noticed by Wollaston in 1802, corresponding to specific wavelengths in the visible light spectrum from the Sun.

In 1859 Kirchhoff and Bunsen began a systematic investigation of these lines and deduced that the dark lines were caused by absorption of radiation by specific elements in the upper layers of the Sun. Comparing these lines with the light spectrum emitted by individual elements on Earth enabled them to identify the elements present in the Sun.

1816 A two wire telegraph system based on high voltage static electricity activating pith balls, using synchronous clockwork dials at each end of the channel to identify the letters, was demonstrated in the UK by Francis Ronalds, an English cheese maker and experimental chemist, and subsequently described in his publication of 1823. Coming only a year after Wellington's victory over Napoleon at Waterloo, it was turned down by the haughty Admiralty, who had just invented semaphore signalling, with the comment "Telegraphs of any kind are now wholly unnecessary". It was an invention before its time and nobody showed any interest. At the time it was however witnessed by the young Charles Wheatstone who was later credited in the UK with the invention of the telegraph.

1816 William Wollaston built the forerunner of the reserve battery. To avoid strong acids eating away the expensive metal plates of his batteries or cells when not in use, he simply hoisted the plates out of the electrolyte, a system copied by many battery makers in the nineteenth century.

1816 Scottish clergyman, Dr. Robert Stirling patented the Stirling Engine a Hot Air external combustion engine first proposed by George Cayley in 1807. Key to the design was an "economiser", now called a regenerator, which improved the thermal efficiency. The first practical engine of this type, it was used in 1818 for pumping water in a quarry. The thermodynamic operating principle, later named the Stirling cycle in his honour, is still the basis of modern Stirling engine applications.

1819 French physicists Pierre Louis Dulong and Alexis Thérèse Petit formulated the law named after them that "The atoms of all simple bodies have exactly the same capacity for heat." In quantitative terms the law is stated as - The specific heat capacity of a crystal (measured in Joules per degree Kelvin per kilogram) depends on the lattice structure and is equal to 3R/M, where R is the gas constant (measured in Joules per degree Kelvin per mole) and M is the molar mass (measured in kilograms per mole). In other words, the dimensionless heat capacity is equal to 3.

Dulong and Petit's Law proved useful in determining atomic weights.

1819 Moses Rogers captain of the passenger ship the SS Savannah converted it from a three masted sailing ship to a paddle steamer by installing a 90 horse power steam engine in it. More a hybrid than a steamship, it was 98 feet long with a displacement of 320 tons. Its fuel storage capacity was very low since the main propulsion was intended to be by the sails with the paddle wheels only coming into use when the wind speed was too low. The paddle wheels were 16 feet (4.9 m) in diameter and unusually, they could be stored on deck when the ship was under sail. A steam ship was such a rare sight that when people saw the ship under steam they thought it was on fire.

In 1819 it crossed the Atlantic from Savannah to Liverpool in 29 days and 11 hours, entering the record books as the first steam ship to make the transatlantic crossing, but the engine was used for a total of about 80 hours during the journey. The return trip was made under sail in rough weather and took 40 hours.

1820 Danish physicist Hans Christian Øersted showed how a wire carrying an electric current can cause a nearby compass needle to move. The first demonstration of the connection between magnetism and electricity and of the existence of a hitherto unknown, non-Newtonian force. Two major scientific discoveries from a simple experiment.

1820 One week after hearing about Øersted's experiment, French physicist and mathematician André-Marie Ampère showed that parallel wires carrying current in the same direction attract eachother, whereas parallel wires carrying current in opposite directions repel eachother.

He also showed that the force of attraction or repulsion is directly proportional to the strength of the current and inversely proportional to the square of the distance between the wires.

He precisely defined the concept of electric potential distinguishing it from electric current. He later went on to develop the relationship between electric currents and magnetic fields.

Ampère's life was not a happy one. Traumatised by his father's execution by the guillotine during the French Revolution, there followed two disastrous marriages, the first one resulting in the early death of his wife. Finally he had to cope with an alcoholic daughter. The epitaph he choose for his gravestone says Tandem Felix ('Happy at last'). The unit of current was named the Ampère in his honour.

1820 French mathematician Jean-Baptiste Biot, together with compatriot Felix Savart , discovered that the intensity of the magnetic field set up by a current flowing through a wire varies inversely with the distance from the wire. This is now known as Biot-Savart's Law and is fundamental to modern electromagnetic theory. They considered magnetism to be a fundamental property rather than taking Ampére's approach which treated magnetism as derived from electric circuits.

1820 Johann Salomo Christoph Schweigger professor of mathematics, chemist and classics scholar at the University of Halle, Germany built the first instrument for measuring the strength and direction of electric current. He named it the "Galvanometer" in honour of Luigi Galvani rather than a "Schweiggermeter"???. Galvani was in fact unaware of the concepts of current flows and magnetic fields.

1820 Dominique François Jean Arago in France demonstrated the first electromagnet, using an electric current to magnetise an iron rod.

1820 American chemist Robert Hare developed high current galvanic batteries by using spiral wound electrodes to increase the surface area of the plates in order to achieve the high current levels used in his combustion experiments. He also used such batteries in 1831 to enable blasting under water.

Hare also developed an apparatus he called the Spiritoscope, designed to detect fraud by Spiritualist mediums, and in the process of testing his machine, he became a Spiritualist convert and eventually became one of the best known Spiritualists in the USA.

1821 Prussian physicist Thomas Johann Seebeck discovered accidentally that a voltage existed between the two ends of a metal bar when one end was cooled and the other heated. This is a thermoelectric effect in which the potential difference depends on the existence of junctions between dissimilar metals (in this case, the bar and the connecting wire used to detect the voltage). Now called the Seebeck effect, it is the basis of the direct conversion of heat into electricity and the thermocouple. See also the Peltier effect discovered 13 years later which is the reverse of the Seebeck effect.

Batteries based on the Seebeck effect were introduced by Clamond in 1874 and NASA in 1961.

1821 The English scientist Michael Faraday was the first to conceive the idea of a magnetic field which he demonstrated with the distribution pattern of iron filings showing lines of force around a magnet. Prior to that, electrical and magnetic forces of attraction and repulsion had been thought to be due to some form of action at a distance.

In 1821 Faraday made the first electric motor. It was a simple model that demonstrated the principles involved. See diagram. Current was passed through a wire that was suspended into a bath of Mercury in the centre of which was a vertical bar magnet. The mercury completed the circuit between the battery and the wire. The current interacting with the magnetic field of the magnet caused the wire to rotate in a circular path around the magnetic pole of the magnet. This was the first time that electrical energy had been transformed into kinetic energy. In 1837 Davenport made the first practical motor but it did not achieve commercial success and for forty years after Faraday's original invention the motor remained a laboratory curiosity with many weird and wonderful designs. Typical examples are those of Barlow (1822) and Jedlik (1828).

This invention was the source of a bitter controversy with Humphry Davy and William Hyde Wollaston, recently President of the Royal Society, who had tried unsuccessfully to make an electric motor. Faraday was unjustly accused of using Wollaston's ideas without acknowledging his contribution. The upshot was that Faraday withdrew from working on electromagnetics for ten years concentrating instead on chemical research.

Consequently it was not until 1831 that Faraday invented a generator or dynamo to drive the motor. Surprisingly nobody else in the intervening ten years thought of it either. Faraday had shown that passing a current through a conductor in a magnetic field would cause the conductor to move through the field but nobody at the time thought of reversing the process and moving the conductor through the field (or conversely moving a magnet through a coil) to create (induce) a current in the conductor.

In an ideal electrical machine, the energy conversion from electrical to mechanical is reversible. Applying a voltage to the terminals of a motor causes the shaft to rotate. Conversely rotating the shaft causes a voltage to appear at the terminals, thus acting as a generator. It was not until 1867 that the idea of a reversible machine occurred to Werner Siemens and practical motor-generators were not realised until 1873 by Gramme and Fontaine.

Faraday, the Father of Electrical Engineering, was the son of a blacksmith. A humble man with no formal education, he started his career as an apprentice bookbinder. Inspired by the texts in the books with which he worked and with tickets given to him by a satisfied customer, he attended lectures in 1812 given by the renowned chemist, Sir Humphry Davy, at the Royal Institution. At each lecture Faraday took copious amounts of notes, which he later wrote up, bound and presented to Davy. As a consequence Faraday was taken on by Davy as an assistant for lower pay than he received in his bookbinding job. During his years with Davy he carried out much original work in chemical research including the isolation new hydrocarbons but despite his achievements he was treated as a servant by Davy's wife and by Davy who became increasingly jealous of Faraday's success. Davy also opposed Faraday's 1824 application for fellow of Royal Society when he himself was president. Davy died prematurely in 1829 at the age of 50, it is said like Scheele, from inhaling many of the gases he discovered or investigated.

Faraday went on to eclipse his mentor discovering electrical induction, inventing the electric motor, the transformer, the generator and the variable capacitor and making major contributions in the fields of chemistry and the theoretical basis of electrical machines, electrochemistry , magneto-optics and capacitors. His inventions and theories were key developments in the Industrial Revolution, providing the foundations of the modern electrical industry, but Faraday never commercialised any of his ideas concentrating more on teaching. He was perhaps the greatest experimenter of his time and although he lacked mathematical skills, he more than made up for it with his profound intuition and understanding of the underlying scientific principles involved which he was able to convey to others. He used his public lectures to explain and popularise science, a tradition still carried on in his name by the IEE today.

Although he was noted for his many inventions, Faraday never applied for a patent.

In 1864 he was offered the presidency of the Royal Institution which he declined. Not so well known is his relationship with Ada Lovelace who idolised him and pursued him over a period of several months in 1844 writing flattering and suggestive letters to which he replied, however in the end he did not succumb to her charms.

When the British Prime Minister asked of Faraday about a new discovery, "What good is it?", Faraday replied, "What good is a new-born baby?"

Saint Michael? - Among Victorian scientists and experimenters, Faraday is revered for his high moral and ethical standards. A deeply religious man, he overcame adversity to become one of the nineteenth century's greatest scientists and an inspiring teacher commanding admiration and respect, but he was not entirely beyond criticism. In 1844 a massive explosion in the coal mine of the small Durham mining village of Haswell killed 95 men and boys, some as young as 10 years old: - most of the male population of the village. The mine owners would accept no responsibility for the disaster and the coroner refused to allow any independent assessor to enter the mine. Incensed, the local villagers took their grievance all the way to the Prime Minister, Sir Robert Peel. Such was the national concern that Peel dispatched two eminent scientists to investigate, Faraday the "government chemist" and Sir Charles Lyell the "government geologist". Their verdict was "Accidental death" and, pressurised by the coroner, they added "No blame should be attached to anyone". In the days before social security, the consequences of this verdict were destitution for the bereaved families.

Faraday's biographers who mention the Haswell mining disaster usually only recount the story that Faraday conducted the proceedings while seated on a sack which, unknown to him, was filled with gunpowder.

1822 English mathematician Peter Barlow built an electric motor driven by continuous current. It used a solid toothed disc mounted between the poles of a magnet with the teeth dipping into a mercury bath, similar in principle to the Faraday disk. Applying a voltage between the shaft and the mercury caused the disc to rotate, the contact with the moving teeth was provided by the mercury.

1822 Probably Britain's greatest engineer, Isambard Kingdom Brunel was sent to France in 1820 at the age of 14 by his father, Mark Isambard Brunel, to acquire a more thorough academic grounding in engineering and to serve an apprenticeship with master horologist and instrument maker Abraham Louis Breguet. Returning in 1822 the 16 year old took up his first job working in his father's drawing office which at the time was preparing the plans for the Thames Tunnel.

In his lifetime Isambard Brunel designed and built 25 Railways, over 100 bridges and tunnels, 3 ships, 8 docks and a pre-fabricated field hospital.

He thought big. Inspired, rather than deterred, by the seemingly impossible, his projects were audacious in scale and ambition, taking engineering way beyond the boundaries of what conventional wisdom believed to be possible with the technology of the day, setting new limits which were not matched by others for decades. A great all round engineer, he turned his hand to architectural, civil, mechanical and naval projects contributing to every detail of the designs. Nor was he afraid to get his hands dirty, helping out the men working on his projects with their manual work when necessary.

Brunel's aspirations may have had no limits, however there was a price to pay for this ambition. He had a prodigious capacity for work and would often be engaged in a number of major projects at any one time, but the actual fulfillment of his projects was carried out by contractors whom he hired and these contractors were frequently driven beyond their limits.

Though his engineering achievements were truly heroic they were not always accompanied by commercial success for his clients and engineering success was often tarnished by unrealistic expectations, aborted projects, missed deadlines, cost over-runs, accidents and in the worst cases, lives lost, and when things went wrong the contractors usually got the blame.

The following are just some of Brunel's achievements:

The Tunnels

  • 1825 - 1843 Thames Tunnel
  • Working for his father on the Thames Tunnel was Brunel's first job. A very difficult project. Previous attempts by Richard Trevithick and others to tunnel beneath the Thames had failed and subsequent formal investigations had judged such a construction to be impracticable. But Brunel and his father persevered despite enormous difficulties and proved the sceptics wrong. See Thames Tunnel.

    It was an experience which gave the young Isambard the confidence to take on many more "impossible" projects over in his subsequent career.

  • 1836 - 1841 Box Tunnel
  • The route for Brunel's Great Western Railway (See below) was designed to follow the most direct route minimising curves and inclines. This necessitated building a tunnel 1.83 miles (2,937 m) long through Box Hill in Wiltshire. At the time,it was the longest railway tunnel in the world.

    Though easier than the Thames Tunnel, the project was not without its difficulties. To speed the construction, work was carried out simultaneously on six separate isolated tunnel sections beneath the hill. They were essentially closed underground chambers until they were able to link up to the adjacent chambers as the excavation of the tunnel progressed. Access to these chambers for the workmen and for removing the excavated earth and rock was through the ventilation shafts,which were up to 290 feet (88 m) deep. Horses at the surface powered the hoists used for this purpose.

    Working conditions were very hazardous. Blasting through the rock in the underground chambers took place with the workmen present and consumed 1 ton of explosives per week. Illumination was by candle light and much of the work was done with pick and shovel. Water ingress had been underestimated and water often gushed from fissures in the limestone strata and from time to time emergency evacuations of the workmen were necessary.

    The project was completed in 1841, one year late and cost the lives of 100 workers.

The Bridges

Though Brunel designed over 100 bridges for his railway projects he did not follow a standard pattern. When the opportunity, or necessity, arose he came up with some sticking and unique designs. The three examples which follow are perhaps his best known. All three are still in use today carrying modern day traffic.

(See pictures of Brunel's Bridges)

  • 1831 - 1864 Clifton Suspension Bridge
  • While convalescing in 1928 from his accident in the Thames Tunnel, Brunel, at the age of 24, submitted a design for his first major project on his own, independent of his father. It was in response to a public tender for a road bridge across the Avon Gorge in Bristol, his home town. Brunel's design was for a suspension bridge with the roadway suspended from chains rather than cables. The main span of 702 ft 3 in (214.05 m) was the longest in its day. In 1931 the results of the tender were announced with Brunel's Clifton Suspension Bridge judged as the winner. Work started immediately but was abandoned in 1843 when Bristol's City Council ran out of funds. After Brunel's death in 1859, work on the bridge was restarted as a memorial to its designer with funds raised by the Institution of Civil Engineers. It was completed in 1864.

  • 1835 - 1838 Maidenhead Railway Bridge
  • The Maidenhead Railway bridge was designed to carry Brunel's Great Western Railway (GWR) over the Thames. As with the Box Tunnel, Brunel's objective was to avoid inclines so that the elevation of the bridge had to be as low as possible above the surrounding fields. At the same time it needed wide spans across the river with high headroom to avoid impeding the river traffic below. Brunel's solution was a brick built bridge with two very wide but at the same time very slender arches of 128 feet (39 m) with a rise of only 24 feet (7 m). At the time it was the widest span for a brick arched bridge and today it still an essential link in the main line carrying high speed trains from London to the West Country.

  • 1848 - 1859 Royal Albert Bridge at Saltash

  • The Royal Albert Bridge is a railway bridge linking Devon with Cornwall spanning the River Tamar at Saltash. Because of the terrain, the railway approaches the bridge from both sides of the river on curved tracks and it was not possible find a simple construction which balanced the horizontal thrust on the bridge piers. Brunel's solution was to use a lenticular truss construction, also known as bowstring girder or tied arch construction, to carry the track bed. Heavy tubular arches in compression formed the top chords of the trusses, and chains in tension formed the bottom chords, balancing the compression forces in the arches. These trusses simply rested on the piers without exerting any horizontal thrust on them. The unique design used two spans of 455 feet (138.7 m) each. Construction started in 1848 and the bridge was opened by Prince Albert in 1859. Like the Maidenhead Bridge it is still carrying mainline rail traffic today.

The Railways

  • 1833 - 1841 Great Western Railway - GWR
  • Despite having no experience in railway construction, in 1833, just four years after the Rainhill Trials had established the viability of public railway systems, at the age of the 27 Brunel was appointed chief engineer for building the Great Western Railway between London and Bristol.

    The estimated price of the route was to be £2.8 million. Government approval was given and construction was started in 1835.

    As was typical of Brunel, he was personally involved in every aspect of the enterprise, from raising the finance to project management and everything in between. He set the highest standards for design and workmanship and took personal charge of every detail of the design, from all the bridges and tunnels along the line, the railway stations at the ends of the line down to the architectural details of their lamp posts and even the contractors' tools.

    Brunel himself surveyed the entire route between London and Bristol, a distance of 118 miles. His target was to minimise inclines and curves so that the trains could run at high speed with increased passenger comfort.

    Responsibility for providing the trains was delegated to Daniel Gooch, an engineer who had trained with Robert Stephenson. For even higher speed and comfort, Brunel specified his trains to run on tracks much wider than the conventional "Stephenson's gauge" of 4 ft 8 1⁄2 in (1,435 mm). He chose to set his tracks 7 ft 0 1⁄4 in (2,140 mm) apart, on what became known as Brunel's "broad gauge". This added significantly to the cost of the bridges, tunnels, embankments and cuttings all along the line and required specially made trains to run on the tracks. This no doubt provided better comfort and speed but it was incompatible with the rest of the rail network making interconnections with the existing railway system difficult. This was one of the first ever standards wars and as has happened many times since, the superior technical system eventually lost out (in 1892) to the inferior system and had to be replaced because the older system had built up a much greater user base. (See The Stockton and Darlington Railway).

    Telegraph signalling using Cooke and Wheatstone's system was installed between Paddington station and West Drayton on 9 April 1839, a distance of 13 miles (21 km). It was the first commercial use of telegraph signalling on the railways.

    Brunel set the standard for railway excellence. When the line was completed in 1841 the alignment was so straight and level that some called the line "Brunel's Billiard Table" and the GWR was affectionately known as "God's Wonderful Railway".

    But the work had cost £6.5 million, more than double the original estimate, and thanks to the problems at the Box Tunnel it was one year late.

High Speed Trains?

  • Brunel's GWR, 118 miles (190 km) long, was completed in 1841, 6 years after approval by parliament, using an army of navvies equipped with only picks and shovels. It used Brunel's unique broad gauge track for which new trains had to be developed and manufactured during the same period.
  • 177 years after the GWR was approved, Britain's new High Speed Train system HS2 connecting London with Manchester and Leeds with 330 miles (531 km) of narrower, standard gauge track was announced by the government in 2012. Using powerful earthmoving equipment, tunneling machines, prefabricated track and bridge sections and automated track laying equipment it is scheduled for completion in 2033, 21 years after initial approval, including time for consultations and further approvals, at a cost of £43 Billion.

The Architecture

The designs for the prestigious railway stations at the termini, and stations in between, of the Great Western Railway are further examples of Brunel's versatility.

The Ships

Brunel's vision extended beyond the shores of Great Britain. He envisaged the Great Western Railway (GWR) as the first link en route to North America with the second link carried by steam-powered iron-hulled ships. Before the GWR was completed he set about fulfilling that dream.

As with all of his projects, his ideas were big. In the case of naval engineering there were good technical reasons justifying his opinions. He was aware that the volume or carrying capacity of a ship is proportional to the cube of its dimensions, whereas the water resistance is proportional to the cross sectional area of the ship below the water line and, to a lesser extent to, the surface area of the ship in the water and these are both proportional to the square of the ship's dimensions. This meant that larger ships would be more efficient and that larger steam powered ships would need comparatively less fuel. This was particularly important for ocean going ships since their range was limited by the amount of fuel they could carry.

There are however practical limits to the size a ship can be, due to the flexing or hogging of the hull as it passes over the waves which affects their seaworthiness. The installation of a heavy steam engine in the ship would tend to make this worse. Wooden-hulled ships are particularly prone to hogging and their length is limited to about 300 feet (100 m) whereas the hull of an iron ship can be made much more rigid and thus less subject to hogging so that much bigger ships are possible. The conclusion was that in order to carry sufficient fuel as well as the cargo across the Atlantic in steam powered ships they would have to be big and preferably iron-hulled.

As ever, Brunel was undaunted by his lack of experience in this new endeavour but went on to design and build three ships that revolutionised naval engineering.

  • 1836 - 1837 SS Great Western
  • Brunel's first ship, the 'Great Western', was the first steamship designed to provide a transatlantic service. It was an oak-hulled, paddle wheel steamer with a displacement of 2300 tons, powered by two Maudslay and Field steam engines with a combined output of 750 horse power driving side-wheel paddles. The hull was reinforced with iron straps to increase its rigidity and it had four masts to carry auxiliary sails. At 236 feet (72 m) long, it was the longest ship in the world and had the capacity to carry128 first class passengers with 20 servants and 60 crew.

    It was launched 1837 and then sailed to London where it was fitted with the engines. On the return journey to Bristol the following year, under her own steam, fire broke out in the engine room. When Brunel went to investigate, he was descending a ladder down into the engine room when it gave way due to damage from the fire and he fell 20 feet (6 m) to the floor landing face down and unconscious in the water being used to douse the flames. Seriously injured once more, he missed the maiden voyage to New York eight days later. As a result of the fire, 50 passengers cancelled their bookings. In 1837, only 9 years after the first demonstration of practical mobile steam power at the Rainhill Trials, the thought of crossing the Atlantic powered by a noisy, newfangled and possibly unreliable steam engine must have terrified the bravest of souls.

    On 4 April 1838, while the Great Western was being readied for the journey, The Sirius, a smaller ship, with a displacement of 1,995 tons, designed to operate a ferry service between London and Cork in Ireland, was chartered by a rival company, British and American Steam Navigation, and left Cork destined for New York instead of London. Similar to the Great Western but smaller, it was a side-wheel, wooden-hulled steamship, 178 feet 4 inches (54.4 m) long with two masts for auxiliary sails, also built in 1837 (by Robert Menzies & Sons in Scotland) but never intended for crossing the Atlantic. Although it was overloaded with the maximum amount of coal it could carry, it was not enough to complete the journey, and the crew burned the cabin furniture, spare yards which carry the sails and one of the masts in their attempt for the Sirius to be the first ship to cross the Atlantic under its own steam. Sailing ships normally did the journey in 40 days, but the Sirius made the crossing in 18 days, 4 hours and 22 minutes at an average speed of 8.03 knots (14.87 km/h).

    The Great Western embarked on her maiden voyage from Bristol, to New York four days after the Sirius left Cork and arrived in New York with 200 tons of coal still aboard just one day after the Sirius, after a crossing 220 miles longer, making the journey in 15 days 5 hours at an average speed of 8.66 knots (16.04 km/h). The Sirius made only one more round trip to New York, whereas the Great Western made a total of 45 round trips for its owners in the following 8 years before it was sold.

    Note: Neither of these ships was the first steamship to cross the Atlantic. That record was claimed in 1819 by the American steamship the SS Savannah which was tiny by comparison.

  • 1839 - 1843 SS Great Britain
  • Brunel made several proposals for a sister ship to the Great Western. His final proposal in 1839 was for the SS Great Britain, designed to carry 252 passengers (later increased to 730) and 130 crew for a cost of £70,000. It was the first to use a screw propeller to drive an iron-hulled steam ocean going ship. Bigger still than the Great Western, it was the largest ship afloat, 322 ft (98.15 m) long with a displacement 3675 tons powered by engines weighing 240 tons with a rated power of 1,000 H.P. and 5 schooner rigged and 1 square rigged mast to carry auxiliary sails. The final cost was £117,000.

    Launched in 1843 the Great Britain was the first iron ship to cross the Atlantic making the voyage from Liverpool to New York in 1845 in a time of 14 days. Screw propellers had recently been claimed by Ericsson to be more efficient than paddle wheels and the Great Britain was fitted with a six bladed screw propeller with a diameter of 15 feet 6 inches (4.7 m), which was only 5% less efficient than modern day propellers. This enabled her to achieve speeds of 11 to 12 knots (20 to 22 km/h).

  • 1854 - 1858 SS Great Eastern
  • In 1852 Brunel was employed by the Eastern Steam Navigation Company to build another ship. His challenge was to design a ship to carry 4,000 passengers with a crew of 418 around the world without refuelling. (At the time there were no bunkering services to refuel ships en route to Australia). To accomplish this the ship would have to be big. Very big!

    His answer was the Great Eastern. Aided by John Scott-Russell, an experienced naval architect and ship builder, Brunel conceived and built the Great Eastern, an iron ship with a displacement of 32,160 tons, it was 692 ft (211 m) long, only 22 % shorter than the 882 ft 6 in (269.0 m) Titanic which was launched 53 years later in 1911. It was powered by five steam engines with a total output power of 8,000 H.P. (6.0 MW). Four of the engines drove two paddle wheels, each 56 feet (17 m) in diameter, and the fifth powered a four bladed screw propeller with a diameter of 24 feet (7.3 m) which enabled the colossal ship to reach a speed of 14 knots (26 km/h). She also had six masts to carry auxiliary sails. The ship was also the first to be constructed with a double-skinned hull, a safety feature which was decades ahead of industry practice.

    Brunel estimated the cost of building the ship to be £500,000. It ultimately cost double that.

    Its keel was laid down on 1 May 1854 and construction took just over three years to complete. (See pictures The SS Great Eastern).

    The launch was scheduled to take place on 3 November 1857 but the enormous ship refused to budge. Two more unsuccessful launch attempts were made first using winches and then hydraulic rams. The ship was finally launched on 31 January 1858, using more powerful hydraulic rams. Fitting out and sea trials took place during the following year and the ship made its maiden voyage in September 1859. This was unfortunately marred by an huge explosion which blew one of the funnels into the air and released steam which killed five stokers, one was drowned and several others were seriously injured. Six days later Brunel, who had been stressed by a series of difficult engineering and financial problems and was already in poor health, suffered a stroke and died at the age of 53.

    In operation the Great Eastern was beset by accidents and failures both technical and commercial. In 1961 it sustained serious damage in a storm losing one of its paddle wheels, smashing the other one and breaking the main rudder shaft to the consternation of passengers. The following year, the New York pilot inadvertently steered the ship onto rocks which opened a gash in the ship's outer hull over 9 feet (2.7 m) wide and 83 feet (25 m) long, some 60 times the area of the damage which caused the sinking of the single hulled Titanic. Fortunately the Great Eastern's double hull saved it from a similar fate.

    Though it may have been an engineering wonder, the Great Eastern was not a commercial success. There was insufficient traffic to fill its great bulk and, in any case, most of the docks and harbours in the world were not big enough to accommodate a ship six times bigger than anything known before so it never sailed on the long routes for which it was planned.

    In 1864 the Great Eastern was sold by auction for £25,000 to Brunel's railway locomotive engineer Daniel Gooch who converted it into a cable laying ship. One of its funnels and some of the boilers were removed and the sumptuous passenger rooms and saloons were ripped out to make way for three huge iron tanks to carry 2,600 miles (4300 km) of cable and the cable paying-out gear on the decks. In 1866 the Great Eastern was used to lay the first successful transatlantic telegraph cable replacing the damaged cable of 1858.

Stepping beyond the boundaries of familiar surroundings into uncharted territory is always subject to meeting unexpected hazards and the possibility of making a wrong turn. Brunel was not immune from this and sometimes rode into a dead end. Unfortunately because of his forceful character he often took a lot of people with him. A couple of examples follow:

Abandoned Projects

In "Man and Superman", George Bernard Shaw wrote "The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.". Perhaps he was thinking of Brunel when he wrote it.

(See picture Brunel - Engineering Superman)

1823 Johann Wolfgang Döbereiner discovered that hydrogen gas "spontaneously" ignited in the oxygen of the air when it passes over finely spread metallic platinum. He used the phenomenon, an example of what we now call catalysis although he was not aware of it, in the design of a "Platinum Firelighter".

1824 Pure Silicon first isolated by Berzelius who thought it to be a metal while Davy thought it to be an insulator.

1824 While steam engines were still in their infancy, twenty eight year old French physicist and military engineer, Nicolas Léonard Sadi Carnot published "Réflexions sur la Puissance Motrice du Feu" ("Reflections on the Motive Power of Fire") in which he developed the concept of an idealised heat engine: the first theoretical treatment of heat engines. He pointed out that the efficiency of a heat engine depends on the temperature difference of the working fluid before and after the energy conversion process. This was later stated as:

η = (Th - Tc)/Th      or      η = 1 - Tc/Th

where η is the maximum efficiency which can be achieved by the energy conversion, Th is the input (hot) temperature of the working fluid in degrees Kelvin and Tc is its output (cold) temperature. This became known as Carnot's Efficiency Law and still holds good today for modern steam turbines and geothermal energy conversion. Carnot also showed that in a reversible process some energy would always be lost providing an early insight into the Second Law of Thermodynamics.

See also Heat engines.

See more about Steam Engines


1825 Ampère quantified the relationship between electric current and the changing magnetic field that produces it, now known as Ampère's Law, and laid the foundation of electromagnetic theory. Ten years later Gauss derived an equivalent equation for electric fields.

1825 British electrician, William Sturgeon credited with inventing the first practical electromagnet (5 years after Arago), a coil, powered by a single cell battery, wrapped around a horseshoe magnet. The world's first controllable electric device.

1825 The Stockton and Darlington Railway, the world's first public railway was opened with George Stephenson at the controls of his steam engine the Locomotion pulling 36 wagons - twelve carrying coal and flour, six for guests and fourteen wagons full of workmen.

Stephenson was self taught and didn't learn to read and write until he was eighteen. Working as an engineman at the colliery in 1813 he was over thirty years old when he was permitted to tinker with the mine's steam engines. One of his early innovations was to use wrought iron rail tracks to replace the brittle cast iron tracks, originally designed for horse drawn wagon ways, to enable them to carry the heavier steam engines.

In 1815 he designed a miners' safety lamp which could be used in coal mines where the seeping of methane gas from the deep coal seams could result in an explosive atmosphere. A year later the well connected Humphry Davy designed a similar lamp which was named the Davy lamp in his honour overlooking the contribution of the diffident Stephenson.

For the Rainhill Trials in 1829, a competition to select the engine for the new Liverpool Manchester railway, Stephenson designed the Rocket a steam engine which reached a speed of 29 m.p.h. (46 km/h) and won the competition outright. This was the first time that people had been conveyed in a vehicle at speeds greater than could be achieved on horseback and caused great excitement. (See diagram of Stephenson's Rocket).

Its performance and adoption by the railway company started a frenzy of railway building - revolutionising the transport of goods, changing the patterns of industrial development, bringing travel within the possibility of the masses and with it - new aspirations. Together with Watt's steam engine, Volta's battery and Faraday's electric motor, the development of the railways was a key driver in the Industrial Revolution.

Stephenson's Rocket used many of the innovations pioneered by Richard Trevithick and established the basic configuration of the steam locomotive. As in Trevithick's Pen-y-Darren engine it used steel wheels on steel rails, high pressure steam, double acting pistons and a "blast pipe" in the chimney. Improved features included flanged wheels rather than the flanged tracks used by Trevethick, a multi-tube boiler with 25 small diameter fire tubes running the length of the boiler to improve the heat transfer from the firebox gases into the boiler water and a more reliable drive system. For lightness and simplicity, only the two front wheels were driven and the drive was by means two horizontal pistons one on either side of the boiler through crank mechanisms directly coupling the piston connecting rods to the wheels.

The basic design principles embodied in the Rocket were soon adopted for steam trains in many countries of the world and endured until the demise of steam trains in the 1960s and the standard (or Stephenson) gauge (the distance between the rail tracks) of 4 ft 8½ in (1,435 mm) adopted by Stephenson for his railways is used in sixty percent of the worlds railways.

In later years George Stephenson was ably aided by his son Robert who contributed to the design of the Rocket and was particularly active in organising the civil works and building bridges to carry the Stephenson's tracks, spreading the railway network throughout the world.

See more about Steam Engines


1825-1843 The Thames Tunnel, the first successful tunnel underneath a navigable river was designed and constructed by Marc Isambard Brunel.

In response to the demand for a much needed land link between the London docks of Rotherhithe and Wapping on opposite sides of the river Thames, Brunel teamed up with a most unlikely partner, Scottish Thomas (Lord) Cochrane (see following footnote), to design a tunneling shield, which they patented in 1818, to facilitate the construction of a tunnel under the river.

They took their inspiration from the feeding and digestive process of the shipworm, "teredo navalis", which, it was claimed, "had sunk more ships than all the cannon ever cast". The shipworm was a huge mollusc, nine inches (230 mm)long and half an inch (13 mm) in diameter. Its body was soft and transparent but its head was formed by jagged shells which bored into, and ground up, the wood which it ate as it bored its way into the ship's timbers, lining and protecting the pathway it left in the bore behind it with petrified excreta.

Their design for the shield envisaged a large frame, weighing 80 tons, with 3 levels, each level with 12 cells or platforms in each of which a miner excavated the wall in front of him. The cells would be open at the back but closed at the front with removable horizontal boards to stabilise the earth on front and to limit water ingress. The boards could be removed one at a time to enable removal of a strip of earth to a depth of 4½ inches (11.5 cm) and then replaced so that the next strip could be excavated. The frame would then be moved forward 4½ inches by hydraulic rams or screw jacks and a masonry lining would be applied to the section of the walls of the tunnel just vacated by the frame to seal it and give it strength after which the process would be repeated until the tunnel was complete.

By 1823, Brunel had produced plans for the tunnel and the Thames Tunnel Company was formed in 1824 with financing secured from prominent private investors who included a local businessman, brother George of William Hyde Wollaston, Vice-president of the Royal Society and son Timothy of Joseph Bramah, inventor of the hydraulic press. They were joined in 1928 when the project as running out of money by others including Henry Maudslay who had made the machines for Brunel's block making factory and the Duke of Wellington, The Iron Duke, hero of the Battle of Waterloo who was by then British Prime Minister. Work commenced in 1825 using Brunel's new tunneling shield and steam driven water pumps to provide the drainage, both manufactured by Maudslay.

Brunel's son Isambard Kingdom Brunel had worked on the planning and design stages of the project with his father and in 1826 at the age of 19 was appointed Resident Engineer in charge of delivering the project.

The work was unfortunately fraught with difficulties. The tunnel was 75 feet (23 m) below the river's surface at high tide but only 14 feet (4.27 M) below the deepest part of the river bed and ran the 1,300 feet (396 m) of its length through gravel, sand, clay and mud. Conditions in the tunnel were most unhealthy and at times highly dangerous suffering from poor ventilation and the constant leaking sewage laden water and several times from flooding when the water broke through the roof. At the time the river itself was like an open sewer, devoid of fish and wildlife. (It was not until 1858, the year of "the Great Stink" that work was started on Joseph Bazalgette's plan for the construction of London's sewage system to manage waste and clean up the river). Accidents were common, many of them fatal. Isambard who often spent 20 hours per day working at the site submitted himself to the same conditions as his workers and paid attention to their needs, meeting and providing for the casualties which inevitably occurred. He was caught himself in one devastating inundation in 1828 and was seriously injured and lucky to escape with his life. Others were not so lucky. All this resulted in delays and cost over-runs until later in 1828 the company ran out of money. Despite pleas from its high profile backers, the company was not able to raise enough cash to carry on and work was suspended for seven years until the project was rescued by Government aid in 1835. This enabled the work to be re-started with a new tunneling shield weighing 140 tons and the tunnel was finally completed in 1843.

Although it was originally intended for pedestrian and horse drawn traffic it eventually became part of London's underground railway system and is still in use today.

  • Footnote:
  • Lord Cochrane was an audacious, charismatic and successful captain in the Royal Navy during the Napoleonic wars and a radical member of the British Parliament to which (aided by bribery) he was elected in 1806. He was however dismissed from both the Navy and Parliament in 1814 after being convicted of fraudulent share trading on the London Stock Exchange. He and his accomplices were charged with perpetrating an elaborate hoax by faking a report that Napoleon had been killed in battle, (a year before the Battle of Waterloo). In the days before the electric telegraph, this could not be verified, and the price of government stocks rose substantially on the news enabling Cochrane and his co-conspirators to sell, at a huge profit, shares which they had acquired just one month before. After his conviction Cochrane returned to the sea, taking charge of the Chilean Navy in late 1818 in their successful revolutionary war of independence from Spain and in 1823 repeating the exploits in Brazil's war of independence from Portugal. A similar role fighting for Greece in their 1827 campaign for independence from the Ottoman Empire had less spectacular results but nevertheless contributed to their success. His exploits became the inspiration for novelist C. S. Forester's fictional hero Horatio Hornblower.

1826 Italian physicist Leopoldo Nobili together with fellow Italian Macedonio Melloni developed a thermoelectric battery based on the Seebeck effect, constructed from a bank of thermocouples each of which provided a very low voltage of about 50 milliVolts. Nobili also invented a very sensitive astatic galvanometer which compensated for the effect of the earth's magnetic field. The pointer was a compass needle suspended on a torsion wire in the current carrying coil. A second compass needle outside of the coil compensated for any external fields.

1826 German physicist and chemist Johann Christian Poggendorff invented the mirror galvanometer for detecting an electric current.

1827 German physicist Georg Simon Ohm discovered the relationship between voltage and current, V=IR, in a conductor which is now called Ohm's Law. The importance of this relationship lies less in the simple proportionality but on Ohm's recognition that Voltage was the driver of current.

1827 Scottish botanist Robert Brown studying the suspension of pollen in water, observed the random movement of the grains we now call Brownian Motion. These random movements which were later quantified using statistical methods are also typical of the movement of electrons and ions in an electrolyte. This causes of this phenomenon were eventually explained in 1905 by Albert Einstein using the kinetic theory of gases.

1828 Berzelius compiled a table of relative atomic weights for all known elements and developed the system of symbols and formulas for describing chemical actions.

1828 Self taught English mathematician George Green, who worked in his family's windmill till the age of forty, published in a local journal in Nottingham with only 51 subscribers, mostly family and friends, An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism. It earned him a place at Cambridge as a mature student but its full importance was not recognised at the time until it was rediscovered by William Thomson (later Lord Kelvin) just after his graduation in 1845. Kelvin recognised this as a seminal influence in the development of electromagnetic theory.

1828 French physiologist and biologist René Joachim Henri Dutrochet discovers osmosis - the diffusion of a solvent through a semi permeable membrane from a region of low solute concentration to a region of high solute concentration. The semi permeable membrane is permeable to the solvent, but not to the solute, resulting in a chemical potential difference across the membrane which drives the diffusion. Thus the solvent flows from the side of the membrane where the solution is weakest to the side where it is strongest, until the solution on both sides of the membrane is the same strength equalising the chemical potential on both sides of the membrane.

Semi permeable membranes are now widely used as separators in batteries and fuel cells allowing the passage of certain ions while blocking others.

1828 Hungarian priest and physicist of Slovak origin, Ányos Jedlik built the first direct current electric motor using an electromagnet for the rotor and a commutator to achieve unidirectional rotation. Jedlik's motor was a shunt wound machine in which a moving electromagnet rotated within a fixed coil, the reverse of modern conventional motors. The wires powering the electromagnet protruded into two small semicircular mercury cups on either side of the shaft. This provided the required commutation as the wires picked up the current from alternate cups as the shaft rotated. Like many motors at the time, it had no practical application, however in 1855 Jedlik built another motor based on similar principles which was capable of carrying out useful work.

In 1861 he demonstrated a self excited dynamo but he did not publish his work. Subsequently Siemens, Varley and Wheatstone were credited with the invention.

Jedlik continued working on high voltage generators and spent his last years in complete seclusion at the priory in Gyór.

1828 Scottish engineer, James Beaumont Neilson patented the hot blast method of air supply to blast furnaces. Preheating the air blown into the furnace, enabled the efficiency of the iron ore smelting process to be improved.

See also Iron and Steel Making

1829Nobili invents the thermopile, an electrical instrument for measuring radiant heat and infra red radiation. It was also based on the Seebeck effect as in Nobili's thermoelectric battery of three years earlier and consisted of a sensor made up from a bank of thermocouples connected in series which generated an electrical current in response to the heat radiation input. The current was measured by an astatic galvanometer, of Nobili's own design. With improvements from Melloni, it found extensive use in nineteenth century laboratories.

1829 French physicist Antoine-César Becquerel, father of a dynasty of famous scientists, developed the Constant Current Cell. The forerunner of the Daniell cell, it was the first non-polarising battery, maintaining a constant current for over an hour unaffected by polarisation. It was a two electrolyte system with copper and zinc electrodes immersed in copper nitrate and zinc nitrate electrolytes respectively, separated by a semi permeable membrane. It was left to Daniell to explain how it worked and thus to get credit for the idea.

1830 The thermostat made from a bi-metallic strip, usually brass and copper, invented by Andrew Ure a Glasgow chemistry professor. It did not find much use for 70 years until the advent of electricity supplies to the home when it could be used to operate a switch.

1830 Joseph Henry in the USA worked to improve electromagnets and was the first to superimpose coils of wire wrapped on an iron core. It is said that he insulated the wire for one of his magnets using a silk dress belonging to his wife. An early example of insulated wire. In 1830 he observed electromagnetic (mutual) induction between two coils and his demonstration of self-induction predates Faraday, but like much of his work, he did not publish it at the time. An unfortunate tendency which he lived to regret. (See 1835 Morse)

The unit of Inductance the Henry is named in his honour.

1831Faraday invented the solenoid and independently discovered the principle of Induction and demonstrated it in an induction coil or transformer. The induction coil has since been "invented" by many others (See 1886 William Stanley).

Faraday discovered that the motion of a magnet could induce the flow of electric current in a conductor in the vicinity of the moving magnet. He was the first to generate electricity from a magnetic field by pushing a magnet into a coil. He put this to practical use with his invention of the generator or dynamo, unshackling the generation of electricity from the battery. Faraday's dynamo, named the Faraday Disk after its construction, was a homopolar machine consisting of a copper disk rotating between the poles of a magnet. Current is generated along the radius of the disk where it cuts the magnetic field and is extracted via brushes contacting the shaft and the edge of the disk. See diagram. The Faraday Disk functions equally well as a motor and although the machine is said to be unique in that it is a direct current machine which does not need a commutator, it does owe something to Barlow's 1922 toothed motor design. (See also Siemens 1867).

From his experiments Faraday defined the relationship now known as Faraday's Law of Induction which states that the magnitude of the emf induced in a circuit is proportional to the rate of change of the magnetic flux that cuts across the circuit. It was left to Maxwell to express Faraday's Law and his notions of Lines of Force in mathematical terms.

1831 Henry demonstrated a simple telegraph system sending a current through a mile and a half of wire to trigger an electromagnet which struck a bell (thereby inventing the electric bell, for many years the main domestic use of the battery). He used a simple coding system switching the current on and off to send messages down the line. Henry thought that patents were an impediment to progress and like Faraday he believed that new ideas should be shared for the benefit of the community. He subsequently freely shared his ideas on telegraphy with S. F. B. Morse who however went on to patent them passing them off as his own.

1831 -1835 Henry developed the relay which was used as an amplifier rather than as a switch as it is used today. At the end of each section, the feeble current would operate a relay which switched a local battery on to the next section of the line renewing the signal level. This enabled signals (currents) to be carried (relayed) over long distances making possible long distance telegraphy. In fact the relay reconstituted the signal rather than amplified it, just as the repeaters used in modern digital circuits do, thus avoiding amplifying the noise. The relay and its use with local battery power to "lengthen the telegraph line" were more of Henry's ideas which he failed to publicise or exploit.

Henry was appointed the first Secretary of the Smithsonian Institution when it was founded in 1846.

For over thirty years telegraphy was the main practical application of the battery, this new found electrical technology.

1832 After witnessing a demonstration of von Sömmering's electrochemical telegraph some time earlier, Baron Schilling an attaché at the Russian embassy in Munich, in turn developed the idea by making an electromagnetic device which he demonstrated in 1832. It was a six wire system which used the movement of five magnetic needles to indicate the transmission of a signal. This was the method subsequently used by Cooke and Wheatstone who later "invented" and patented the five needle electric telegraph for two way communications in 1837.

1832 Hippolyte Pixii built his "magneto generator" the first practical application of Faraday's dynamo. The term "magneto" means that the magnetic force is supplied by a permanent magnet. His first machine rotated a permanent magnet in the field of an electromagnet generating an alternating current for which there was no practical use at the time. The following year at Ampère's suggestion he added a commutator to reverse the direction of the current with each half revolution enabling unidirectional - direct current to be produced. Pixii's magneto liberated electrical experimenters from their dependence on batteries.

1833 Faraday published his quantitative Laws of Electrolysis which express the magnitudes of electrolytic effects and galvanic reactions, putting Volta's discoveries and battery theory on a firm scientific basis.

  • The amount of a substance deposited on each electrode of an electrolytic cell is directly proportional to the quantity of electricity passed through the cell.
  • Faraday's Constant, named in his honour, represents the electric charge carried on one mole of electrons. It is found by multiplying Avogadro's constant by the charge carried on a single electron, and is equal to 9.648 x 104 Coulombs per mole. It is used to calculate the electric charge needed to discharge a particular quantity of ions during electrolysis.

  • The quantities of different elements deposited by a given amount of electricity are in the ratio of their chemical equivalent weights.

With William Whewell, he also coined the words, electrode, electrolyte, anode (Greek - Way in), cathode (Greek - Way out) and ion (Greek - I go) .

1833 Samuel Hunter Christie of the British Royal Military Academy publishes a bridge circuit for comparing or determining resistance, later to be called the Wheatstone Bridge.

1833 German physicist Wilhelm Eduard Weber, working with Gauss, demonstrated "the world's first electric telegraph" using a moving magnet and a coil of wire to send a signal along a wire suspended from a church spire in Gottingen to the other side of the town, a distance of 3 kilometers. One of many such claims before and since. The system used a simple coding scheme switching the current on and off, similar to Henry's, combined with reversing the polarity of the current to deflect a compass needle in opposite directions, to send different letters down a single wire. Over the subsequent years Weber investigated terrestrial and induced magnetic fields and verified the theoretical laws put forward by Ampère and others using electrical instruments which he designed for this purpose. The unit of Magnetic Flux is named the Weber in his honour.

1833 Russian physicist Heinrich Friedrich Emil Lenz formulated Lenz Law which states that an induced electric current flows in a direction such that the current opposes the change that induced it. A special case of the Law of Conservation of Energy. The law explains that when a conductor is pushed into a strong magnetic field, it will be repelled and that when a conductor is pulled out of a strong magnetic field that the magnetic forces created by the induced currents will oppose the pull. This also explains the phenomenon of back emf in electric motors, that is, the voltage created by the moving armature which opposes the applied voltage and hence the movement of the armature itself. Lenz law was later extended for more general application by Le Chatelier.

In the same year he also showed that the resistance of a metal increases with temperature.

1833 Scottish chemist Thomas Graham discovers the rate at which a gas diffuses is inversely proportional to the square root of the density of the gas. Now known as Graham's Law of Diffusion. Diffusion however is not confined to gases, it can take place with matter in any state. It may take place through a semi permeable membrane, which allows some, but not all, substances to pass. In solutions, when the liquid solvent passes through the membrane but the solute (dissolved solid) is retained, the diffusion process is called osmosis, a process which is used in many battery designs.

1833 British engineer Isambard Kingdom Brunel brought bad news to his father Marc Isambard Brunel about the "Gaz Engine" on which they had been working for 10 years. After consultations with Humphry Davy in 1923, the elder Brunel concluded that closed cycle hot air engines similar to Stirling's engine could be more fuel efficient than steam engines which lost a significant quantity of water in every cycle, an opinion which was shared by many at the time including Michael Faraday and the British Admiralty. He then began working on a closed cycle engine using "carbonic acid gas" (Carbon dioxide) which was relatively easy to liquefy under pressure. The engine had two reservoirs for the condensed gas which could be alternately heated (vaporised) and cooled by hot and cold water and these two gas sources were used to propel a double acting piston. The idea was patented in 1825 and, joined by the younger Brunel, they made several demonstrators using pressures up to 120 atmospheres. (The hot air engine had originally been conceived to avoid the explosions of high pressure steam boilers). Based on intuition, as were many inventions of the day, a huge amount of money was invested in the project. Eventually the younger Brunel was able to make use of early thermodynamic theories to justify the project. Unfortunately his conclusion in 1833 was that "No sufficient advantage on the score of economy of fuel can be obtained", and the project was abandoned.

1833 Undeterred by the experience of the Brunels (see previous paragraph above), flamboyant, Swedish born, engineer John Ericsson patented in Britain his "caloric engine" a double-acting external combustion hot air engine in which expansion occurs simultaneously on one side of the displacer piston with compression on the other. It was similar to a Stirling engine (patented in 1816) in which the displacer also acts as the power piston but it used an open cycle instead of a closed cycle design.

Ericsson had left his home country for England in 1826 where he entered a design for a railway locomotive in the Rainhill Trials. Although his design "Novelty" was the fastest in the competition, he lost out to Stephenson's Rocket on reliability grounds. Ericsson, an irrepressible self publicist and showman made extravagant claims for his caloric engine which he was not always able to substantiate.

His next ventures were a stream of inventions for naval applications including the ship's screw propeller, a variant of the Archimedes Screw, which he patented in 1836 (though earlier designs by Scottish inventors James Steadman(1816) and Robert Wilson (1827) and others existed but had not been patented). The superior efficiency of the screw propeller was demonstrated by the British Admiralty in 1845 in a competition between two similar sized Navy steam sloops, the Rattler with a screw propeller and the Alecto driven by paddle wheels. On a calm day in the North sea, coupled together stern to stern, they engaged in a "tug-of-war". The Rattler won, pulling the Aleco backwards at a speed of 2.8 knots. It was argued that this was not a fair trial since the Rattler's engines produced 300 horse power compared to only 141 horse power for those of the Alecto, but the Admiralty had already made up its mind and the spectacle gave them the convincing publicity they wanted.

Discredited by his failure to demonstrate the benefits claimed for the caloric engine and failing to interest the British Admiralty in the propeller and after a series of business losses and a spell in a debtors' prison Ericsson left Britain in 1839 for the USA where he continued to work on the caloric engine for 20 years. Though he sold may examples of his caloric engine, interest faded when he was unable to show its superiority to the steam engine. He was however more successful as a naval architect and munitions designer, his most famous design being the USS Monitor the "ironclad" used to great effect by the Union's forces in the U.S. Civil War.

1834 French clockmaker Jean Charles Athanase Peltier discovered that when a current flows through a closed loop made up from two dissimilar metals, heat is transferred from one junction between the metals to the other and one junction heats up while the other cools down. Used as the basis for refrigeration products with no moving parts. This is now known as the Peltier effect and is the reverse of the Seebeck effect discovered 13 years earlier.

1834 French engineer and physicist, Benoît Paul Émile Clapeyron published "Puissance Motrice de la Chaleur" ("The Driving Force of the Heat") in which he developed further Carnot's work on heat engines. He showed how the heat cycle relationship between the volume and pressure of the working fluid as well as the work due to expansion and contraction could be presented and analysed in graphical form.

He also showed that the work done on, or by, a working fluid such as steam can be determined using calculus. Thus:

W = ∫ PdV (integrated between the initial volume Vi and the final volume Vf)

where W is the work done on, or by, the steam, V is its volume and P is its pressure.

1835 German mathematician Carl Friedrich Gauss quantified the relationship between the electric flux flowing out a closed surface and the charge enclosed in the surface. Now know as Gauss's Law it is the electrical field equivalent ofAmpère's Law for magnetic fields. It was not published however until 1867.

Gauss also did pioneering work on probability and statistics, defining and characterising the Normal Distribution, now also named the Gaussian Distribution in his honour. It is the theoretical basis of much of today's quality control of which Six Sigma is an example.

Gauss was one of the worlds most gifted and prodigious mathematicians making major contributions to geometry, algebra, statistics, probability theory, differential equations, electromagnetics, and astronomy. Working alone for much of his life Gauss' personal life was, like Ampère's, tragic and complicated. His first wife died early, followed by the death of one of his sons, plunging him into a depression which was not helped by an unhappy second marriage which also ended with the early death of his second wife.

While he was working, when informed that his wife is dying Gauss replied: "Ask her to wait a moment - I am almost done. "

1835 Samuel Finley Breese Morse, American artist and professor of the Literature of the Arts of Design in the University of the city of New York and religious bigot with a mandate directly from God, made a career change at the late age of 41 and started work on telegraphy. Undaunted by his lack of knowledge of the principles of electricity, he sought the assistance in developing his ideas, first from a colleague Leonard Gale of the University of New York who pointed out to Morse the need for insulation on the windings of his electromagnets, and then from Joseph Henry who already had a working telegraph system and who explained the need for relays to extend the range of the system. Morse subsequently patented Henry's ideas in his own name. He demonstrated the "first" electric telegraph in 1835 ignoring many prior claims dating as far back as Gray in 1729, Morrison's design of 1753 and Salvá's in 1804 as well as more practical recent inventions by Henry in 1831 and Weber in 1833.

Morse patented his system in 1837 and although it came after the needle telegraphs of Schilling (1832) and that of Cooke and Wheatstone (1837) which was patented earlier the same year as Morse's, Morse's system was simpler and more robust using only a single signalling wire plus a return wire and its use spread very quickly.

Morse subsequently claimed sole authorship for these ideas and also for the relay, another of Henry's inventions ignoring Henry's essential contributions to the system thus creating an irreparable rift with Henry. Similarly, the coding system Morse Code on which single channel telegraphy depends was based on existing technology including Henry's ideas, as well as those of Gauss and Weber, which Morse developed jointly with Albert Vail, Morse's business partner. It was Vail who invented the Morse key and also the printing telegraph which was patented in Morse's name. Their relative contributions are still in dispute. (See also 1841 Bain)

Henry is reported to have said in later life "If I could live my life again, I might have taken out more patents".

The Communications Revolution

Before the advent of the electric telegraph, communications had been limited by the speed of the fastest horse or the fastest ship. It took anything from four to six months to send a message from Britain to Australia and the same time to send a reply back. The telegraph reduced this to minutes, but it didn't just increase the speed of communications, it also dramatically increased the value of the information transmitted. Think of railway signalling which enabled safer movement of trains or military communications which gave commanders intelligence about the enemy's position and enabled rapid deployment of their own assets. Similarly, government or business administrators could monitor the status of remote operations giving them timely opportunity to intervene or to revise their own plans. Think also of commercial networks which could provide time sensitive commercial information to market traders or speculators giving them a competitive advantage.

The electric telegraph also facilitated both the gathering and dissemination of information and brought better understanding of unfamiliar people, places and communities, the first step towards the so called "Global Village".

Providing timely access to information, and the ability to communicate with remote locations transformed news reporting, knowledge of world events, trade, travel, warfare, diplomacy, administration and long range personal and business relationships much more dramatically than today's Internet Revolution.

See also the Transatlantic Cable


For 35 years the battery was a solution looking for a problem. It had been used on a small scale as a laboratory tool providing the energy for electrolysis in the analysis of chemical compounds and the isolation of new elements but it was Morse's electric telegraph which eventually created the deployment of batteries on an industrial scale.

1835 Electric arc welding proposed by James Bowman Lindsay of Dundee. The idea was eventually patented fifty years later by Benardos and Olszewski in 1885.

Lindsay had many bright ideas, including the design for an electric light which he demonstrated in 1836 and several innovations in the field of telegraphy but none of these were ever commercialised.

1836 Demonstration by a British chemist John Frederic Daniell of the Daniell cell, a two electrolyte system using two electrodes immersed in two fluid electrolytes separated by a porous pot.

Volta's simple voltaic cell cannot operate very long because bubbles of hydrogen gas collect at the copper electrode acting as an insulator, reducing or stopping further electron flow. This blockage is called polarisation. Daniell's cell overcomes this problem by using electrolytes which are compatible with the electrodes. Thus the zinc electrode is suspended in an electrolytic solution of zinc sulphate which is contained in the porous pot (Initial designs used sulphuric acid rather than zinc sulphate). The porous pot is in turn immersed in the copper sulphate solution which is contained in a glass jar into which the copper electrode is also suspended. The Daniell cell does not produce gaseous products as a result of galvanic action and copper rather than hydrogen is deposited on the cathode. Daniell's non-polarising battery was thus able to deliver sustained, constant currents, a major improvement on the Voltaic pile.

The Daniell cell chemistry was also available in other configurations which provide superior performance such as the gravity cell or crowfoot cell which eliminated the porous pot.

Daniell's cell was however based on a similar non polarising battery design demonstrated by Becquerel in 1829 which used nitrate electrolytes rather than the sulphate electrolytes used by Daniell. Despite the prior art, Daniell, rather than Becquerel, is remembered as the inventor of the non-polarising cell.

Early galvanic cells were all based on acidic electrolytes and many of these designs produced hydrogen at the cathode causing the cell to become polarised. Two approaches were adopted to solve the polarisation problem. Daniell's solution was a non-polarising cell which did not produce hydrogen. The other alternatives were depolarising cells containing oxidising compounds which absorbed the hydrogen as it was produced and did not allow the build up of bubbles. The Leclanché cell which uses manganese dioxide as a depolariser is an example of this type.

1836 Although it had been known for many years that some chemical processes could be speeded up by the presence of some unrelated chemical agent which was not consumed by the chemical action and that the phenomenon had been used by Döbereiner and others, it was Berzelius who in 1836 introduced the term catalyst and elaborated on the importance of catalysis in chemical reactions.

1836 Electric light from batteries shown at the Paris Opera.

1836 Parisian craftsman Ignace Dubus-Bonnel was granted a patent for the spinning and weaving of glass. His application was supported by a small square of woven fibreglass. The drawn glass was kept malleable by operating in a hot vapour bath and weaving was carried out in a room heated to over 30°C.

1836 Irish priest, scientist, and inventor, Nicholas Joseph Callan, working at Maynooth Theological University in Ireland, invented of the induction coil. He discovered that by interrupting a low current through a small number of turns of thick copper wire making up the primary winding of an induction coil, a very high voltage could be induced across the terminals of a high turns secondary winding of thinner copper wire on the same iron core. Such induction coils are used in the automotive industry to operate the sparking plugs, but in the other industries they are generally known as Ruhmkorff coils.

The importance of Callan's pioneering work was not recognised at his remote institution which had other priorities and he never received recognition for this invention which is now associated with the name of German-born Parisian instrument maker, Heinrich Ruhmkorff. Like all instrument makers, he put his name on every instrument he made and Callan's coil eventually become known as the "Ruhmkorff Coil".

Callan also developed a galvanic cell known as the Maynooth Battery in 1854.

1837 Faraday discovers the concept of dielectric constant, invents the variable capacitor and states the law for calculating the capacitance. The unit of Capacitance the Farad is named in his honour.

1837 Sixteen years after the principle was demonstrated by Faraday, self taught American blacksmith Thomas Davenport patented the first practical electric motor as "an application of magnetism and electro-magnetism to propelling machinery." Powered by a galvanic battery consisting of a bucket of weak acid containing concentric cylindrical electrodes of dissimilar metals, the motor was a shunt wound, brush commutator device. The magnetic field of the stator was provided by two electromagnets. Two further electromagnets formed the spokes of a wheel which acted as the rotor. The commutator reversed the polarity of the rotor electromagnets as they passed the alternate north and south poles of the stator to create unidirectional rotation. It was granted the first ever patent for an electrical machine.

Davenport's "revolutionary" invention was ahead of its time and it did not bring him the commercial success his efforts deserved. At the time, the lack of suitable batteries or any other source of electrical power to drive the motor inhibited its adoption and his persevering endeavours to improve and promote the motor led him into bankruptcy. His pioneering use of electromagnets in both the stator and the rotor of his machine went largely unnoticed until the idea was reinvented simultaneously by Varley, Siemens and Wheatstone in 1866 for use in their designs for dynamos. It was not until forty years after Davenport's invention that the demand for electric motors eventually took off. Unfortunately Davenport didn't live to see it. He died aged 49 in 1851.

1837Patent granted for a Needle electric telegraph (Two way electric communications) conceived by William Fothergill Cooke, a retired English surgeon of the Madras army studying anatomy at the University of Heidelberg, and refined by physicist Sir Charles Wheatstone of King's College, London. (See 1816 Ronalds) This was claimed to be the first practical battery powered telegraph, however it is very similar to Schilling's design of 1832. An elegant design, instead of using one wire for each letter it used only five signalling wires plus a return wire. By using a combination of the five signalling needles the number of wires could be reduced. When activated, the needles pointed to individual letters on a board. Twenty different letters could be identified by only five wires. There was no provision for sending the letters C, J, Q, U, X and Z. The design was overtaken by the simpler single wire system devised Morse using his coding system of dots and dashes. The relationship between Cooke and Wheatstone eventually ended acrimoniously over a dispute about their respective contributions to the design.

In 1839, Cooke and Wheatstone's telegraph was installed on Brunel's Great Western Railway where, on 1 January 1845, it was successfully used to enable the apprehension of murderer John Tawell fleeing from the scene of his crime on a train travelling from Slough to Paddington. After he boarded the train a telegraph message was sent from Slough, alerting police in London who were able to arrest him on arrival at his destination. It was an event which stirred the public interest in telegraphy which up to that time had been regarded as no more than a scientific curiosity.

Wheatstone claimed many inventions in his lifetime, usually some time after they had been invented by somebody else. Apart from the needle telegraph see the electric clock , punched tape and the dynamo. At least he acknowledged that the Wheatstone Bridge was invented by somebody else.

1837 First commercially available insulated wire made by British haberdasher W. Ettrick who adapted silk wound "millinery" wire, used in hat making, for electrical purposes. The same year William Thomas Henley made a six head wire wrapping machine for manufacturing silk insulated wire and founded Henley Cables.

1837 James W. McGauley of Dublin invented the self acting circuit breaker in which the electric current moved an armature which opened the circuit switching off the current. When the current was removed the armature moved back to its original position and switched on the current once more causing the armature to oscillate and the current to be switched rapidly on and off. The same year American inventor Charles Grafton Page built a similar device which he called a rocking magnetic interrupter. The original purpose of these devices was to provide current pulses to the primary of an induction coil causing repetitive high voltage sparks at the terminals of the secondary winding. This trembler mechanism was subsequently widely used in electric bells, buzzers and vibrators.

1838 Scottish engineer Robert Davidson built a DC electric motor based on iron rotor elements driven by pulses from electromagnets in the stator. It was the first example of what we would now call a switched reluctance motor. The motor comprised two electromagnets one on either side of a wooden rotor and three axial iron bars equally spaced around the periphery of the rotor. The electromagnets were switched on and off in turn by means of a mechanical commutator driven from the rotors.

Davidson used four of these motors to drive a 5 ton electric locomotive on the newly opened Edinburgh/Glasgow railway in 1842 reaching a speed of 4 mph over a distance of one and a half miles.

The vehicle was powered by two large batteries constructed from wooden troughs each with 20 cells containing sulphuric acid in which were suspended zinc and iron electrodes. The motor speed was controlled by lowering or raising the electrodes into and out of the acid. A resin sealant protected the wooden cells from attack by the acid.

Like Davenport's motor, Davidson's motor was also ahead of its time and was not developed into a practical product. The more efficient electromagnetic rotors and stators as pioneered by Davenport, became the norm and the reluctance motor was forgotten. It was however revived in the 1960's when new semiconductor technology made electronic commutation possible and, because of its simplicity, the reluctance motor finds many uses today.

1838 Carl August von Steinheil a German physicist discovers the possibility of using the "earth return" or "ground return" in place of the current return wire for the signal in telegraph circuits thus enabling communications using a single wire.

1839 Steinheil builds the first electric clock.

1839 Welsh lawyer Sir William Robert Grove demonstrates the first Fuel Cell. Attempting to reverse the process of electrolysis by combining hydrogen and oxygen to produce water, he immersed two platinum strips surrounded by closed tubes containing hydrogen and oxygen in an acidic electrolyte. His original fuel cell used dilute sulphuric acid because the reaction depends upon the pH when using an aqueous electrolyte. This first fuel cell became the prototype for the Phosphoric Acid Fuel Cell (PAFC) which has had a longer development period than the other fuel cell technologies.

The same year Grove also demonstrated an improved two electrolyte non-polarising galvanic cell using zinc and sulphuric acid for the anodic reaction and platinum in nitric acid for the cathode. Known as the Grove cell it provided nearly double the voltage of the first Daniell cell. Grove actually developed a rechargeable cell however there were few facilities for recharging at that time and the honour for inventing the secondary cell eventually went to Planté in 1860. Grove's nitric acid cell was the favourite battery of the early American telegraph systems (1840-1860), because it offered high current output. However it was found that the Grove cell discharged poisonous nitric dioxide gas and large telegraph offices were filled with gas from rows of hissing Grove batteries. Consequently, by the time of the American Civil War, Grove's battery was replaced by the Daniell battery.

In later life (1880) Grove became a high court judge.

1839 The Magnetohydrodynamic (MHD) Generator proposed by Michael .

1839 Prussian engineer Moritz Hermann von Jacobi financed by Czar Nicholas makes first electric powered boat using 128 Grove cells. He also formulated the law known as the Maximum Power Theorem or Jacobi's Law which states: "Maximum power is transferred when the internal resistance of the source equals the resistance of the load". Also known as Load matching.

In 1838 von Jacobi also discovered electroforming by which duplicates could be made by electroplating metal onto a mould of an object, then removing the mould. This galvanic process was used for making duplicate plates for relief or letterpress printing when it was called electrotyping.

1839 Alexandre-Edmund Becquerel discovered the photovoltaic effect when he was only nineteen while experimenting with an electrolytic cell made up of two metal electrodes placed in an electrically conducting solution. He noticed that small currents were generated between the metals on exposure to light and these currents increased with the light intensity. This new source of electricity never had the same impact as the Volta's cells since the currents were small and the phenomenon was largely ignored by the scientific community. 100 years later Becquerel's discovery was recognised as the first known example of a P-N junction. See also Becquerel 1896

1839 Polystyrene isolated from natural resin by German apothecary Eduard Simon however he was not aware of the significance of his discovery which he called Styrol. Its significance as a plastic polymer with a long chain of styrene molecules was recognised by Staudinger in 1922.

1840 James Prescott Joule an English brewer published "On the Production of Heat by Voltaic Electricity" showing that the heat produced by an electric current is proportional to I2R now known as Joule's Law. He also discovered that electrical power generated is proportional to the product of the current and the battery voltage and he established that the various forms of energy, mechanical, electrical, and heat - are basically the same and can be changed, one into another. Thus he formed the basis of the law of Conservation of Energy, now called the First Law of Thermodynamics. See also Joule's work on refrigeration.

1840 Robert Sterling Newall from Dundee patented a wire rope making machine suitable for manufacturing undersea telegraph cables. It was used to make the first successful telegraph cable connecting England and France in 1851 and later with others the first transatlantic telegraph cable. The cable was insulated with gutta-percha, the adhesive resin of the isonandra gutta tree, introduced to Europe in 1842 by Dr. William Montgomerie, a fellow Scot working as a surveyor in the service of the East India Company. Gutta percha was used for 100 years for cable insulation until it was eventually replaced by polyethylene (commonly called polythene) and PVC.

1840 Electroplating, a process discovered by Cruikshank forty years earlier, was re-invented by the Elkingtons of Birmingham and commercialised by Thomas Prime. Articles to be plated were suspended as one electrode in a bath containing an electrolyte of silver or gold dissolved in cyanide. When the voltage was applied to the electrodes the metal was deposited on the suspended article.

1840 Eminent British mathematician and Astronomer Royal, George Biddell Airy, develops a feedback device for continuously manoeuvring a telescope to compensate for the earth's rotation. Problems with his mechanism led to Airy becoming the first person to discuss instability (hunting or runaway) in closed-loop control systems and the first to analyse them using differential equations. Stability criteria were later established by Maxwell.

Feedback control systems were not new. The list below gives some examples from earlier times:

  • 270 B.C. Greek inventor and barber Ktesibios of Alexandria invented a float regulator to keep the water level in a tank feeding a water clock (the clepsydra - Greek water thief) at a constant depth by controlling the water flow into the tank.
  • 250 A.D. Chinese engineer Ma Chun invented the cybernetic machine, also called the south pointing carriage, models of which can be found in several museums throughout the world. Based on connecting the wheels through a system of differential gears to a pointer, usually in the form of a statuette with an outstretched arm, the pointer always points south no matter how far the carriage has travelled or how many turns it has made. Legend has it that a Chinese general used south pointing chariots to guide his troops against the enemy through a thick fog.
  • 1620 Dutch engineer living in England Cornelius Drebbel invented the thermostat for his stove. It depended on the expansion and contraction of a liquid to move a damper which controlled the air flow to the fire.
  • 1745 Scottish blacksmith and millwright Edmund Lee added a fantail to the moveable cap of the windmill, perpendicular to the main sails, to keep the main sails always pointing into the wind.
  • 1749 English clockmaker John Harrison used a bi-metallic strip to compensate for temperature changes affecting the balance springs in his clocks. As the temperature rises the bi-metallic strip reduces the effective length of the balance spring to compensate for its expansion and change in elasticity.
  • 1787 English carpenter Thomas Mead regulated the speed of rotation of a windmill using the displacement of a centrifugal pendulum to control the effective area of the sails.
  • 1788 James Watt designed the centrifugal flyball governor to control the speed of his steam engines by adjusting the steam inlet valve.

Considering his track record, Airy surprisingly held the post of Astronomer Royal, the highest office in the British civil service, for forty six years. Filled with his own self importance he belittled the work of those whom he considered his social inferiors such as Faraday whose mathematics, in his view, wasn't up to scratch and John Couch Adams who predicted the existence and orbit of the planet Neptune and whom Airy ordered to proceed slowly and re-do his calculations "in a leisurely an dignified manner". Consequently Airy missed its eventual discovery which was scooped by Frenchman Urbain Jean Joseph Le Verrier.

In his role as chief scientific advisor to the government he put a premature end to Babbage's pioneering work on computers with his verdict, "I believe the machine to be useless, and the sooner it is abandoned, the better it will be for all parties", which cut off all government funding for the project.

Airy also advised against the construction of the Crystal Palace to house the Great Exhibition of 1851 because he said the structure would collapse when the salute guns were fired. Despite Airy's objections, it was built anyway and was a great success.

After the Tay Bridge disaster in 1879 when the bridge collapsed into the river during a storm killing all 75 passengers on the train passing over it at the time, the subsequent investigation found that Airy, who who provided the wind loading for designer Thomas Bouch, seriously miscalculated the effect of a Tayside gale on the structure, and that the bridge would have fallen "even if construction had been perfect".

1840 "Steam Electricity" , electrostatic discharges produced by the frictional electrification of water droplets, observed by a colliery "Engine Man" near Newcastle in England when probing a steam leak. The phenomenon was investigated by local lawyer, (later to be engineer and arms manufacturer), William George Armstrong who constructed what he called a Hydro-Electric Generator using the effect to produce electrostatic charges on demand. It consisted of a boiler insulated from the ground generating a jet of steam from which sparks could be drawn on to an insulated metallic conductor. The conductor became positively charged, while the boiler acquired a negative charge.

See also Kelvin's Thunderstorm for an explanation.

1841 The non-polarising Carbon-Zinc cell, substituting the cheaper carbon for the expensive platinum used in Grove's cell, invented by German chemist Robert Wilhelm Bunsen. His battery found large scale use for powering arc-light and in electroplating.

Bunsen did not invent the eponymous burner for which he is famous. The basic burner was in fact invented by Faraday and improved by Peter Desaga, a technician working for Bunsen at the University of Heidelburg. The improved burner was designed to provide the high temperature flames needed for Bunsen's joint studies of spectroscopy with Kirchhoff and Desaga was smart enough to manufacture and sell the new device under his boss's name.

Bunsen never married. He was a popular teacher who delighted in working with foul smelling chemicals. Early in his career he lost the use of his right eye when an arsenic compound, cacodyl cyanide, with which he was working, exploded.

1841 Scottish clockmaker Alexander Bain invented the first pendulum electric clock. Bain demonstrated his clock to Charles Wheatstone who copied the clock and three months later demonstrated it to the Royal Society claiming it as his own invention. Fortunately, unknown to Wheatstone, Bain had already patented the invention.

Bain also proposed a method of generating electricity to power his clock by means of an earth battery. This consisted of two square plates of zinc and copper, about two feet square, buried deep in the ground a short distance apart forming a battery with the earth acting as the electrolyte. Such an arrangement produces about one volt continuously.

1842 Austrian physicist Christian Andreas Doppler explained that the apparent frequency of waves as experienced by an observer depends on the relative motion between the observer and the source, the wavelength being shorter for an approaching source and longer for a receding source. He used the analogy of a ship sailing into or retreating from the waves to explain his hypothesis, but sceptics were not convinced and so in 1845 he set up an experiment to demonstrate the effect. He arranged for a trumpeter to ride on an open train carriage and, as a reference, for two trumpeters to be positioned (stationed) in a railway station. All three trumpeters were to hold the same note as the train passed through the station. His experiment verified that the pitch of the moving trumpet heard by an fixed observer at the station was higher than the pitch of the stationary trumpets as the train approached the station and lower than the stationary trumpets as the train was leaving the station. Known as the Doppler effect it was shown by Fizeau in 1848 that the effect also applied to light (electromagnetic) waves.

The principle of the Doppler effect is used extensively today in radar applications and highway speed traps to determine the speed of moving objects by measuring the frequency shift of signals bounced off the speeding vehicles.

1843 Alexander Bain patented a device to scan a two-dimensional surface and send it over wires. Thus, the patent for the fax machine and the first use of scanning to dissect and build up an image was granted 33 years before the patent was given for the telephone. Over a period of five years Bain designed and patented many improvements to the electric telegraph including the use of punched tape (re-invented by Wheatstone and sold to Samuel Morse in 1857) which were widely adopted at the time. Unfortunately he derived no financial benefit from his ideas. His efforts and his money were spent in pursuing patent infringements by Samuel Morse and he retired into a life of obscurity, poverty and hardship.

1843 The first computer program was written by Augusta Ada Byron, Countess of Lovelace to calculate values of a Bernoulli function. Known as Ada Lovelace she was the beautiful daughter of romantic English poet Lord Byron and wife of the Earl of Lovelace. At the age of 14 she was tutored by famous mathematician Augustus De Morgan at the University of London and became the world's first software engineer. Convinced of her own genius she let everybody know it at every opportunity. She worked as an assistant to Charles Babbage on the development of his "analytical engine" the world's first programmable computer which used punched cards for input and gears to perform the function of the beads of an abacus.

Before Babbage, computing devices were mostly analogue, performing calculation by means of measurement, Babbage's machine however was digital, performing calculation by means of counting. It is claimed that Ada originated the concept of using binary numbers, a practice used in all modern computers, however Babbage's difference engine and more versatile analytical engine were both based on the decimal numbering system. Her notes indicate that she understood and used the concepts of a stored program, as well as looping, indexing, subroutine libraries and conditional jumps, the first use of logic in a machine, however the extent of Babbage's contribution to these thoughts and how much was her own work is not clear. She wrote "The Analytical Engine ... weaves algebraic patterns, just as the Jacquard-loom weaves flowers and leaves." Though her contribution to the technology may be questioned, her charm did wonders for Babbage's PR (although it didn't quite work on Michael Faraday).

Ada however managed to run up considerable gambling debts with her lover John Crosse and as a solution she applied her mathematical prowess to fresh fields developing a winning "system" for betting on horses (proving, incidentally, that genius and common sense don't always go hand-in-hand). Unfortunately, the horses being unaware of their responsibilities, the system didn't win and Ada finished her life as a bankrupt, alienated from her family, addicted to laudanum (opium), dying a painful death from cancer of the cervix at the age of 36, repeating the demise of her father, also an opium addict who died of a fever at same age of 36.

Babbage did not have the financial resources to complete his machines and he appealed to the Prime Minister Robert Peel for help, but after taking advice from the formidable Astronomer Royal Sir George Airy, the request was turned down and his machines were never finished. In 1991 the British Science Museum completed the construction of Babbage's Difference Engine No.2 from Babbage's original drawings with new components and it worked just as he said it would, performing its first test calculation for the public, the powers of seven (y=x7) for the first 100 values.

1843 Sir Charles Wheatstone "found" a description of the Christie's 1833 bridge circuit, now known as the Wheatstone Bridge, and published it via the Royal Society though he never claimed he invented it.

The same year Wheatstone also invented the Rheostat (Greek - "Rheo" Flowing stream) variable resistor.

1843 Patents for the vulcanisation of natural rubber with sulphur to improve its strength, wearing properties and high temperature performance were awarded to Thomas Hancock in England in May 1843 and one month later to Charles Goodyear in the USA. Subsequently patents for hard rubber called vulcanite or ebonite, created by using excess sulphur during vulcanisation, were granted to Hancock in England in 1843 and to Nelson Goodyear (brother of Charles) in the USA in 1851.

Ebonite is a hard, dark and shiny material initially used for jewellery, musical instruments, decorative objects and dental plates (with pink colouring) for nearly 100 years. It is also a good insulator and soon found use in electrical equipment and power distribution panels.

Ebonite was a milestone because it was the first thermosetting material and because it involves modification of a natural material.

Ebonite mouldings were exhibited by both Hancock and Goodyear at the Great Exhibition of 1851.

1843 German founder of modern electro physiology Emil du Bois-Reymond discovered that nerve impulses were a kind of "electrical impulse wave" which propagated at a fixed and relatively slow speed along the nerve fibre. In 1849, using a galvanometer wired to the skin through saline-soaked blotting paper to minimise the contact resistance, he was able to detect minute electrical discharges created by the contraction of the muscles in his arms. Realizing that the skin acted as an insulator in the signal path, he increased the strength of the signals by inducing a blister on each arm, removing the skin and placing the paper electrodes within the wounds. He determined that a stimulus applied to the electropositive surface of the nerve membrane causes a decrease in electrical potential at that point and that this "point of reduced potential", or impulse, travels along the nerve like a wave.

Galvani's theory of animal electricity vindicated at last? See also nerve impulses.

1845 Michael Faraday discovers that the plane of polarisation of a light beam is rotated by a magnetic field. The first experimental evidence that light and magnetism are related. Now called the Magneto-Optic effect or the Faraday effect.

1845 Gustav Robert Kirchhoff a German physicist at the age of 21 announced the laws which allow calculation of the currents, voltages, and resistances of electrical networks. In further studies, based on Kelvin's mathematical representation of the circuit elements, he demonstrated in 1857 that current flows through a conductor at the speed of light.

Kirchhoff formed a productive working partnership with Bunsen at the University of Heidelburg where they discovered the that the flames of each element had a unique emission and absorption visible light spectrum, founding the science of emission spectroscopy for analysing and identifying chemical substances. They invented the spectroscope which allowed them to analyse not only laboratory samples, but also the Fraunhofer lines in cosmic light spectra and by comparing them with the dark lines in the spectrum of earthly elements they could determine the composition of the Sun and the stars by spectral analysis of the radiation they emit.

After an accident in early life, Kirchhoff spent most of his working life in a wheelchair or on crutches.

1846 The Smithsonian Institution established in the USA, "for the increase and diffusion of knowledge among men" with a large endowment from English chemist and mineralogist, James Smithson, in neat symmetry with the founding of the Royal Institution in England by the American, Count Rumford. Joseph Henry was chosen as the Smithsonian's first distinguished Secretary. Smithson never visited the United States but after he died his remains were brought there for burial.

1846 From his experiments on magneto optics Faraday discovered that some substances such as heavy glass and Bismuth are repelled rather than attracted by magnets and named the phenomenon diamagnetism. Using the analogy with dielectrics and conductors he made the distinction between diamagnetics - "poor conductors of magnetic force" and paramagnetics - "good conductors of magnetic force".

1846 The birth place of the modern oil industry was Baku in Azerbaijan, then part of the Soviet Union, where the first "modern" oil well was drilled in 1846 by local mining engineer V. Semyonov. It was followed by others in Bobrka in Poland (1854), Bucharest in Romania (1857), Lambton County, in Ontario, Canada (1858) and Titusville in the USA (1859). Except for the 1857 Canadian well which was originally dug by hand, all of these so called "modern" wells used the same percussion drilling techniques, also called cable tool drilling, that the Han Chinese had pioneered in their oil fields 2000 years before.

In 1898, the Russian oil industry exceeded the U.S. oil production level and by 1901, Baku produced more than half of the world's oil.

Though it was not the first, the Titusville oil well drilled by Edwin Laurentine Drake in 1859 is usually considered to be the West's first commercially viable source of oil.

Drake's is a sad story. An ex railroad conductor with no engineering or drilling experience he had retired from the railroad at the age of 38 due to ill health. Around the same time, the Pennsylvania Rock Oil Company had been formed to exploit oil deposits which were seeping from land in various locations, particularly around Titusville in Pennsylvania, but financial difficulties caused the break up of the company which re-emerged with a low capital base as The Seneca Oil Company.

In 1858 Drake invested in Seneca Oil and he was hired by them with a salary of $1,000 per year. Giving him the nickname of "Colonel" to impress the local residents, Seneca Oil sent him to Titusville to investigate the oil deposits there. He set about building a drilling rig based on traditional percussion drilling methods but using a steam engine for repetitively raising the heavy drill bit. He devised improvements for drilling through the bedrock, housing the bit in an iron pipe to prevent the borehole from collapsing but the work took longer than expected. When Seneca Oil, having invested $2,000 in what appeared to be a dry hole, refused to provide any more capital to purchase essential equipment, Drake used his own money to fund the work. After many difficulties and scorn from the locals he struck oil in August the following year at a depth of 69½ feet (21 metres). Almost immediately Drake's methods, which he failed to patent, were copied by others in the vicinity and America's oil boom was launched.

Unfortunately Seneca Oil did not pay Drake's salary for more than two years, eventually paying him off in June 1860 with a payment of $2,167. By 1862 much more productive wells had come on stream causing the price of oil to drop and Seneca Oil with its original low capacity wells went out of business. The man who had made countless people very rich died in poverty, an invalid, confined to a wheelchair at the age of 61.

1847 Ignoring the difficulties encountered with previous experimental Atmospheric Railways including the Croydon railway by built by William Cubitt in 1846, as well as warnings from experienced engineers such as Daniel Gooch and Robert Stephenson, in 1847 Isambard Kingdom Brunel launched his his own atmospheric railway connecting Exeter with Newton Abbot in Devon, a distance of 20 miles (32 km).

This system did not use heavy locomotives on the track to pull the carriages. Instead the carriages were pulled along by a piston moving in a pipe laid between the tracks. A large stationary engine ahead of the train pumped air out of the pipe and the pressure differential between the partial vacuum in front of the piston and the atmospheric pressure behind it caused the piston to move along the pipe. The piston was connected to the floor of the carriage by means of a plate which slid in a slot at the top of the pipe and the vacuum was maintained by airtight leather flaps, rivetted to the pipe, which opened as the plate passed through and closed again after it passed. Brunel's railway used 15 inch (381 mm) pipes on the level sections, and 22 inch (559 mm) pipes for the steeper gradients. Pumping stations were situated every three miles along the line and trains could run at 20 miles per hour (32 km/h).

The advantages of this system were that there were no heavy locomotives on the track, the stationary engines were more efficient, more reliable and easier to maintain, there were fewer problems with traction on the gradients, and the passengers would not be subject to the noise and smell of the steam engine.

Disadvantages were mainly associated with the seal around the piston and, more importantly, maintaining the vacuum seal in the slot which was its Achilles heal. Apart from wear and tear, the leather flaps were attacked by vermin and damaged by frost in the winter. Various lubricants were tried to keep the leather supple including cod oil, soap, beeswax and tallow but the problems with the seals remained. Less serious problems were the inconvenience of decoupling the carriages from the piston at the end of each section and reconnecting them to the piston in the next section. Furthermore the trains could not be run in reverse. Running costs however were another major problem. It was calculated that Brunel's atmospheric traction cost 3s 1d per mile (£0.10/km), compared to 1s 4d (£0.04/km) for conventional steam power.

In view of these insurmountable difficulties the project was abandoned in 1848 after only one year and the line returned to conventional locomotive haulage. The shareholders in the system had lost £500,000.

1848 Scottish physicist, born in Belfast, William Thomson (later Lord Kelvin) established the basis for an absolute temperature scale. Starting from the experimental results of Charles and Gay Lussac, Kelvin showed also that there is an absolute zero of temperature which is -273°C. The absolute temperature scale is named the Kelvin scale in his honour and -273°C is called 0°K or absolute zero.

Kelvin was an infant prodigy in mathematics, entering Glasgow University at the age of ten, he started the undergraduate syllabus when he was only fourteen and published his first scholarly papers, correcting errors in the works of both Fourier and Fourier's critics, when he was only sixteen. Fourier remained an inspiration to him throughout his early years. Kelvin always sought practical analogies to explain his theories and published over 600 scientific papers on mathematics, thermodynamics, electromagnetics, telecommunications, hydrodynamics, oceanography and instrumentation and he filed 70 patents. He is remembered for his work on the Transatlantic Telegraph Cable but he initially gained fame by estimating the age of the earth from a knowledge of its cooling rate at over 100 million years (later revised and broadened from 20 to 400 million years) in contradiction of the prevailing religious, creationist view of the world. Despite this he maintained a strong and simple Christian faith throughout his life and engaged in a long running public disagreement with Charles Darwin, remaining "on the side of the angels", claiming that, according to his calculations, the age of the earth was too short for Darwin's evolutionary changes to have taken place. (Current estimates give the age of the earth as 4.6 billion years taking into account the heating effect of radioactivity of the earth's core, something of which Kelvin could not have been aware). He remained actively involved in scientific work until he was 75 but in later life he found it difficult to accept Maxwell's theories, for which he himself had been the Genesis, and the concept of radioactivity.

According to C. Watson, Kelvin's biographer, "During the first half of Thomson's career he seemed incapable of being wrong while during the second half of his career he seemed incapable of being right."

1849 President Abraham Lincoln was granted a U.S. patent number 6469 for a device for lifting riverboats over shoals [shallow water], the only U.S. president ever to have been awarded a patent. Part of his application read, "Be it known that I, Abraham Lincoln, of Springfield, in the county of Sangamon, in the state of Illinois, have invented a new and improved manner of combining adjustable buoyant air chambers with a steam boat or other vessel for the purpose of enabling their draught of water to be readily lessened to enable them to pass over [sand] bars, or through shallow water, without discharging their cargoes...".

The device was never manufactured.

1849 The first accurate terrestrial measurement of the speed of light was made by French physicist Armand Hippolyte Louis Fizeau. Previous measurements had been based on observations of the movement of planets and moons by Danish astronomer Ole Christensen Rømer (1676), English astronomer James Bradley (1728) and others. Fizeau directed a beam of light through the gaps in a rotating cog wheel to a mirror several miles away and observed the reflection of the pulses of light coming back through gaps in the wheel. Depending on the speed of rotation of the wheel, the returning light would either pass though the gap or be blocked by a tooth. The speed of light could be calculated from the distance to the mirror, the number of teeth on the wheel and its rate of rotation. He determined the speed of light to be 186,000 miles per second or 300,000,000 metres per second.

Also known as Einstein's constant, the speed of light is represented by the symbol c for "celeritas" (Latin - "speed").

Fizeau also showed that the Doppler effect also applied to lightwaves.

1849 The Bourdon tube pressure gauge was patented by French engineer Eugene Bourdon. It is still one of the most widely used instruments for measuring the pressure of liquids and gases of all kinds, including steam, water, and air up to pressures of 100,000 pounds per square inch as well as pressures below atmospheric. It consists of a "C" shaped or spiral curved tube sealed at one end which tends to straighten out when a pressurised fluid is admitted into it. The displacement of the end of the tube is used to move a pointer or other indicator.

1850 Prussian born theoretical physicist Rudolf Julius Emmanuel Clausius publishes his seminal paper "On the Mechanical Theory of Heat" establishing the study of Thermodynamics and outlining the basis of the Second Law. In 1865 Clausius defined the notion of entropy.

1850 The trembler electric bell invented by John Mirand.

1851 In his treatise "On the Dynamical Theory of Heat." Kelvin formally states the Second Law of Thermodynamics, that "Heat does not spontaneously flow from a colder body to a hotter". It was later restated in the form "In a closed system entropy can only increase", recognising the concept of entropy proposed by Clausius in 1865.

1851 German inventor Heinrich Daniel Ruhmkorff patents the Ruhmkorff Induction Coil capable of producing sparks 30 centimetres long. Basically a high turns ratio transformer, it was invented in 1836 by Irish priest Nicholas Callan.

1851 French physicist Léon Foucault proved for the first time that the earth rotated on its axis by suspending a 28 kg brass-coated lead bob pendulum on a 67 meter long wire from the dome of the Panthéon in Paris. The plane of the pendulum's swing, though fixed, appeared to rotate by 360 degrees during the course of the day thus indicating the rotation of the earth.

In 1852 Foucault performed similar experiments with gyroscopes. Though he was not able to sustain the rotation of the rotor for a full day, he was able to demonstrate that over a short period of time before friction slowed the rotor, the gyroscope maintained a fixed position in space independent of the earth's rotation.

See more about Gyroscopes.

1851 American inventor and entrepreneur Isaac Merritt Singer invented the Singer Sewing Machine. Like many great inventors his inspiration drew on prior art to which he added his own contributions which brought the commercial success which had eluded his predecessors. In this case he improved the lockstitch mechanism of Elias Howe (See below), making it more reliable. He changed the needle movement from "side to side" to "up and down" enabling the use of a straight, rather than curved needle, and also enabling the machine to sew on a curved path. He also added automatic feed of the cloth and a presser "foot" to hold the cloth down against the upward stroke of the needle, and he introduced the foot treadle to power the movement of the needle and shuttle, replacing the hand-cranked mechanism used in all previous machines.

His major innovation however was in the marketing of the product. Previously sewing machines had been designed for industrial use and Singer launched the first domestic models in 1856 and pioneered the introduction of the Hire Purchase Agreement or Installment Payments, with $5 securing a machine, followed by monthly payments of $3 until the full purchase price was paid off. This allowed people of modest means to acquire relatively expensive capital goods. He later adopted the policy of accepting trade-ins against new purchases. These measures in turn increased the potential market for the machines and allowed the introduction of mass production methods for the first time, reducing the costs and increasing market potential still further. By 1870 the price of a new machine had been reduced to only $30.

Singer expanded into the European market, establishing a factory in Clydebank, near Glasgow, controlled by the parent company, becoming one of the first American-based multinational corporations, with agencies in Paris and Rio de Janeiro.

Singer's machine came towards the end of the Industrial Revolution which had largely benefited the textile industry with the mechanisation of spinning and weaving. His sewing machine dramatically reduced the time to make up garments while simultaneously improving both the quality and strength of the stitching giving further impetus to the textile industry by providing new markets for the increased textile production.

According to Brian Coats of the eponymous thread company, "To put sewing mechanisation into perspective, a skilled seamstress can manage 40 stitches per minute (spm) at full speed. The earliest machines claimed speeds of about 250 spm, Singer's machine in the 1850s could reach 900, and a contemporary domestic machine can do 1,500. Industrial machines will now get up to 10,000 spm and can sew coarse fabrics such as canvas and denim so fast that they will catch fire."

Just as important as the improvement in efficiency however, the sewing machine provided a means for families not just to make their own clothing, but also to start a small family businesses to supplement their incomes and improve their lives.

There had been many attempts at designing sewing machines in the past leading up to, and perhaps influencing, Isaac Singer's design in 1851 but most were unreliable or expensive and failed to gain commercial acceptance. These antecedents included the following:

  • 1755 German inventor Charles Weisenthal awarded an English patent for his invention of a sewing needle for use in a machine, but the description of the machine was not included in the patent, so it is unknown whether he actually designed a machine as well.
  • 1790 English inventor and cabinet maker, Thomas Saint was issued the first patent for a complete machine for sewing. It is not known if Saint actually built a working prototype of his invention. The patent describes an awl that punched a hole in leather and passed a needle through the hole. A later reproduction of Saint's invention based on his patent drawings did not work, though it did with work when some modifications were made.
  • 1810 German hosiery maker, Balthasar Krems developed an automatic machine for sewing caps but did not patent it. Like many others it never functioned well and was forgotten.
  • 1804 A French patent was granted to English inventors Thomas Stone and James Henderson for "a machine that emulated hand sewing."
  • The same year a British patent was granted to Scottish inventor John Duncan for an "embroidery machine with multiple needles."

    Both inventions failed and were soon forgotten by the public.

  • 1814 Austrian tailor, Josef Madersperger was issued a patent for a machine which made embroidery stitches, but it could not sew seams. By 1839 he had also received a patent for a machine suitable for chain stitching but this was not considered to be successful.
  • A chain stitch is formed by a single thread introduced from one side of the material only and is normally used for hemming or temporary stitching. It will unravel rapidly if the last stitch in the chain is not secured.

  • 1818 The first American sewing machine was invented by pastor John Adams Doge and John Knowles. Their machine failed to sew any useful amount of fabric before malfunctioning.
  • 1830 The first practical sewing machine was patented by the French tailor, Barthelemy Thimonnier. His machine had no transport mechanism, with the cloth being moved forward by hand, and used only one thread and a hooked needle that made an acceptable chain stitch like that used in embroidery. He set up a garment factory with 80 of his machines and had contracted with the French army to manufacture their uniforms but he was almost killed by an angry group of French tailors who feared being put out of work by his new invention and burned down his garment factory in 1841. Thimonnier died bankrupt in England.
  • 1833 American Walter Hunt invented the lockstitch sewing machine. In traditional lockstitch sewing, the needle thread interlaces with a separate under-thread, which is on a small bobbin over which the needle thread can pass to lock the stitch in place. This is a much more secure structure than the chain stitch.
  • Hunt's machine had two spools of thread and a curved needle with the eye at the point rather than in the shank as in conventional hand sewing needles. Hunt's needle passed the thread through the fabric in an arc motion; creating a loop on the other side of the fabric and a second thread carried by a shuttle running back and forth on a track passed through the loop creating a lockstitch. It was the first time an inventor moved away from attempting to duplicate hand sewing motions. Unfortunately his machine was only suitable for sewing straight seams.

    He later lost interest in the device because he believed his invention would cause unemployment and never patented it.

    Hunt also invented the safety pin.

  • 1844 The earliest known patent for a sewing machine which used two threads and the combination of an eye-pointed needle and a shuttle to form couched stitches was granted to Englishmen John Fisher and James Gibbons who received the patent for a lace making machine which was almost identical to the machines later made by Howe and Singer. The commercialisation of Fisher's machine was hampered by poor preparation of his patent application and subsequent legal challenges by Howe and Singer.
  • 1846 The first American patent was issued to Elias Howe of Spencer, Massachusetts for "a process that used thread from two different sources". It was basically a refinement of Hunt's idea. With a price tag of $300, equivalent of six months' wages, no single family could afford such a machine and Howe struggled to attract commercial interest in his invention in America. Trying his luck in England he eventually sold his first machine there but ended up in a debtors' prison in 1849.
  • Returning to Massachusetts he discovered that "his" lockstitch mechanism was being copied by many others and he embarked on a series of incessant law suits to protect his design. The most serious offender was Isaac Singer whose machine used the same lockstitch mechanism that Hunt had invented, but which Howe had patented, and in 1854 Howe sued Singer for patent infringement. The courts upheld Howe's patent, since Hunt had abandoned his design and not filed patent, giving Howe the exclusive patent rights to the eye pointed needle and Singer, as well as all others, had to pay royalties to Howe for the use of the patent on every machine manufactured.

    Howe then saw his annual income jump from $300 to more than $200,000 a year.

    In 1856 Howe, Singer and two other sewing machine manufacturers, "Grover & Baker", and "Wheeler & Wilson" agreed to pool their various patents creating the Sewing Machine Combination which extracted royalties of $15 per machine for the use of their patents by others.

    Between 1854 and 1867, Howe earned close to $2 million from his invention. During the Civil War, he donated a portion of his wealth to equip an infantry regiment for the Union Army and served in the regiment as a private.

    Elias Howe died in 1867, the year his patent expired.

  • 1849 American John Bachelder from Boston patented a sewing machine with a belt to feed the fabric along a horizontal sewing surface, though his invention was still only capable of making chain stitches. The patent for his feed mechanism was later sold to Singer.
  • 1851 American inventor, Allen B. Wilson, developed the rotary hook shuttle used extensively in lockstitch sewing machines which enabled much faster, vibration-free sewing speeds and the intermittent four-motion feed for advancing the material between stitches which is still used today.

Singer lived an unconventional lifestyle. He ran away from home at the age of eleven to join a travelling stage act and became a consummate showman who put his talents to good use in promoting his machines. He also lived a life of polygamy, marrying his first wife when she was only fifteen and subsequently fathering at least 24 children with seven common law wives and various mistresses.

On the darker side, when his business partner George Zeiber, fell seriously ill and was not expected to survive, Singer persuaded him to sign over his share of the company's assets which were at the time worth around $500,000 for only $6,000. Zeiber had helped Singer to start up the sewing machine company by giving him his entire life savings of $1,700 in return for a full share of the venture and even contributed his own ideas for improvement to the designs. Zeiber recovered however and though he managed to obtain menial employment from the company he never received any offer of compensation for his blatantly immoral treatment.

1852 English chemist Edward Frankland invented the notion of chemical bond and introduced the idea of valency, that an atom of one element could only compound with a definite number of atoms of another element.

1852 Joule and Kelvin (William Thomson) discovered that when a gas is allowed to expand without performing external work, the temperature of the gas falls. Now known as the Joule-Thomson Effect, it is the basis of nearly all modern refrigerators and gas liquefaction processes. (The Peltier Effect is also used in some special cooling applications)

For an explanation see Refrigeration Systems in the section on Heat Engines.

1852 American engineers William F. Channing and Moses Gerrish Farmer installed the first municipal electric fire alarm system using a series of electric bells and call boxes with automatic signaling to indicate the location of a fire in Boston, twenty four years before the advent of the telephone.

Farmer was a prolific inventor in the same mould as Edison. In the same year (1852) he also demonstrated diplex telegraphy, the simultaneous transmission of two signals in the same direction down a wire (or channel), the first example of time division multiplexing (TDM). It was based on two rotating switches, one at each end of the line which connected the transmission line alternately to each transmitter / receiver pair permitting sequential, interleaving of signals from each channel. Unfortunately he was not able to develop it into a practical system because of the difficulty of synchronising the receivers with the transmitters, a problem which was not solved until 1874 by Baudot.

In 1858 he did however patent a two battery duplex system similar to Gintl's 1853 design. (See next). As with the diplexer, there were obstacles to overcome before practical duplexers were ready for roll out. In this case it was the design by Stearns in 1872 which took the honours.

In 1853 Farmer also patented an improved battery.

1853 The electric burglar alarm patented by American Minister Augustus Russell Pope. When a door or window was opened, it closed an electrical contact initiating an alarm. The rights to the patent were purchased by Edwin Holmes who began manufacturing and selling the alarms in 1858 and was subsequently credited with its invention.

1853 Austrian telecommunications engineer Julius Wilhelm Gintl working in Vienna, invented a method of duplex telegraphy, the simultaneous transmission of two signals in opposite directions down a wire (or channel). The first telecommunications duplexer - allowing simultaneous message transmission and reception. It was a two battery, "compensating" system with differential relays, in which two samples of the transmitted signal were arranged to cancel eachother in the local receiving relay but were able to operate the remote receiving relay normally.

In 1855 German engineer Carl Frischen working for Siemens & Halske registered of a patent for a simplified version of Gintl's design with only one compensating battery.

1853 Almost 200 years after Newton, Scottish engineer William John Macquorn Rankine introduced the concept of potential energy for stored energy (In mechanical terms - energy based on position). Together with Kelvin they applied the concept to electrical potential whose unit of measurement they named the volt.

1853 Mathematical representation of the voltage-current relationships of capacitors (i = C dv/dt) and inductors (v = L di/dt) derived by Kelvin enabling the analysis of RLC circuits and the performance of telegraph cables. A more detailed model of the cable or transmission line, based on Kelvin's theory, but taking into account the distribution of the capacitance and inductance along the line, was developed by Kirchhoff in 1857.

1854 The fundamental idea of the electrical transmission of sound (the telephone) was published in the magazine "L'Illustration de Paris" by Belgian experimenter Charles Bourseul, working in France.

1854 Heinrich Geissler, a master glassblower in Bonn, Germany, was the first to make use of improved vacuum technology to create a series of astonishingly beautiful evacuated glass vessels into which he sealed metal electrodes. Geissler's vacuum tubes emitted brilliant and colourful fluorescent light when energised by a high voltage which aroused the interest of both scientists and artists of his day.

1854 English mathematician George Boole published "An Investigation of the Laws of Thought, on Which Are Founded the Mathematical Theories of Logic and Probabilities" in which he expressed logical statements in mathematical form. Now known as Boolean Logic it also used a binary approach to represent whether statements were true or false. It made little impact at the time until twelve years latter it was picked up and developed by American logician Charles Sanders Pierce. However it remained in obscurity until it's value was recognised by Claude Shannon in 1937 and used to make improvements to Vannevar Bush's analogue computer the differential analyser. Overnight it became the basic information processing concept used in all modern computers.

Boole's wife, Mary Everest, niece of Sir George Everest after whom the mountain was named, was not blessed with the same logical mind as her husband. in 1864 at the age of 49 Boole caught a serious cold after walking two miles in the rain and giving a lecture still dressed in his wet clothes. His wife believed that a remedy should resemble the cause. She put him to bed and threw buckets of water over the bed since his illness had been caused by getting wet. Boole died of pneumonia.

1854 Irish inventor John Tyndall, in a demonstration at the Royal Institution, directed a beam of sunlight into the path of the curved stream of water pouring from a container. Due to total internal reflection at the boundaries of the water stream with the air, the light followed a zig zag path inside the arc of the water stream which acted as a light pipe. This is the phenomenon on which fibre-optics are based today.

Tyndall was a prolific inventor as well as a renowned populariser of science in the mould of Michael Faraday whom he counted among his friends.

Experimenting with cures for insomnia he died at the age of 73 from an overdose of chloral, a sedative administered by his wife.

1854 Scottish chemist John Stenhouse invented the gas mask. It was based on the ability of powdered charcoal to absorb large volumes of gases. Carbon based absorbers are still the most common filters in use today

1854 Italian priest and engineer Eugenio Barsanti in partnership with hydraulic engineer Felice Matteucci patented a four stroke, spark ignition internal combustion engine running on coal gas. They failed to sufficiently promote their business and when Barsanti died at the age of 43 in 1864 Matteucci was unable to carry on alone and Otto's recent (1862) similar design became the industry standard.

1855 British chemist and inventor Alexander Parkes produced the first synthetic (man made) plastic. By dissolving cellulose nitrate in alcohol and camphor containing ether, he produced a hard solid which could be molded when heated, which he called Parkesine (later known as celluloid). Unfortunately, Parkes could find no market for the material. In the 1860's, John Wesley Hyatt, an American chemist, rediscovered celluloid and marketed it successfully as a replacement for ivory. Thus was born the plastics industry which brought new opportunities to the electrical industry for both insulation and packaging.

1855 English engineer and inventor, Henry Bessemer patented a more effective, fast and inexpensive method of mass-producing steel from pig iron, essentially purifying the iron by blowing air through the molten metal to oxidise the impurities, thus converting the pig iron into steel, in a large pear shaped tilting retort or furnace known as a Bessemer converter. The initial process was successful in removing the impurities from the iron but it also removed too much of the carbon, the amount of which controlled the properties of the steel, and it left excess oxygen in the steel.

British metallurgist Robert Mushet came to the rescue with a solution to manage the carbon content of the steel more precisely by adding to the mix, small, controlled quantities of spiegeleisen (German Spiegel - mirror and Eisen - iron), an alloy containing approximately 15% manganese and small quantities of carbon and silicon. The carbon in the spiegeleisen replaced the carbon lost in the Bessemer conversion and the manganese removed the surplus oxygen.

Bessemer's steel was much stronger than wrought iron and cast iron whose serious weaknesses had been exposed in some construction projects. The Bessemer conversion, together with the innovations introduced by Thomas in 1876, reduced the costs of steel making by about 80% reducing the costs of steel rails and opening up new applications for steel in railways, construction, ship building, cable making and armaments. Steel was also less expensive than wrought iron which it rapidly replaced.

Bessemer was a prolific inventor with at least 129 patents to his name and made his first fortune selling "gold" paint, enabling passable imitations of the very expensive ormolu to be made. It was made from fine powdered brass suspended in a paint like solution. Rather than patenting it, he kept the process a closely guarded secret, carrying out parts of the production in four separate locations so that nobody could know the complete process. Bessemer's gold paint was used to adorn much of the gilded decoration which was popular at the time, and brought him great wealth.

See also Iron and Steel Making

1856 As an extension to his "dynamical theory of heat" published in 1851, Kelvin submitted a paper to the Royal Society outlining the "dynamical theory of electricity and magnetism" treating electricity as a fluid. It was these ideas which led Maxwell to develop his theory of electromagnetic radiation published in 1873.

In the same year Kelvin invented the strain gauge based on his discovery that the resistance of a wire increases with increasing strain.

1857 Following his discovery the previous year that the resistance of a conductor increases with increasing strain Kelvin also discovered that the resistance also changes when the conductor is subjected to an external magnetic field, a phenomenon known as magnetoresistance. In bulk ferromagnetic conductors, the main contributor to the magnetoresistance is the anisotropic magnetoresistance (AMR). It is now known that this is due to electron spin-orbit interaction which leads to a different electrical resistivity for a current direction parallel or perpendicular to the direction of magnetisation. When a magnetic field is applied, randomly oriented magnetic domains tend to align their magnetisation along the direction of the field, giving rise to a resistance change of the order of a few percent. The the AMR effect has been used for making magnetic sensors and read-out heads for magnetic disks. See also GMR

1857 Wheatstone introduced the first application of punched paper tapes (Ticker tapes) as a medium for the preparation, storage, and transmission of data (another one of Bain's ideas) which was rapidly adopted in the USA to speed up the transmission of Morse code.

1858 The laying of the first Transatlantic Telegraph Cable from two wooden warships, Agamemnon and Niagra, was completed. - One of the greatest engineering feats of the nineteenth century. Financed by American entrepreneur Cyrus Field, it was designed and supervised by arrogant and incompetent amateur electrician, the aptly named, Dr Edward Orange Wildman Whitehouse, a former surgeon from Brighton. The cable was made up from seven copper strands carrying the signal, insulated with a treble layer of gutta percha held together by a jute yarn impregnated with tar, pitch, boiled oil and beeswax. The protective armouring consisted of eighteen strands of seven wires each of charcoal iron bright wire and the total weight of the cable was one ton per mile. The signal was carried in one direction by the cable while the return path was through the earth.

Unfortunately the cable failed after less than a month in use, almost before the celebrations were complete, having transmitted only 732 messages. At its peak, over a period of 20 days, the cable was able to transmit in one direction 271 messages with an average of 10 words each, and 129 messages in the other direction, but the transmissions got steadily weaker becoming lost in the noise until it was taking half a day or more to send a message.

The signal pulses were generated from Daniell cells whose voltage was augmented using induction coils. In an attempt to solve the problem of weak signal levels, Whitehouse, advised by Morse it is claimed, increased the battery voltage from 600 Volts to 2000 Volts with disastrous results causing the breakdown of the cable's insulation. Kelvin, a consultant on the project, had advocated solving the weak signal problem by using more sensitive receiving equipment. He had the same year patented a mirror galvanometer (originally devised by Poggendorff in 1826) which enabled the detection of very weak signals for this purpose which arch rival Whitehouse was reluctant to use, preferring his own detectors. Kelvin's work on this high profile project and his design and management of the subsequent successful cable, laid by Brunel's Great Eastern and the Archimedes, in 1866 enhanced both his reputation and his bank balance as well as his already considerable ego.

One of the last messages sent over the original cable before it failed was from the British government to General Trollope, commander of the British forces in Halifax, Nova Scotia, rescinding an order to send two regiments of troops to help quell the Indian Mutiny, a rebellion against British rule. The original order had been sent by ship, the fastest way possible, a few weeks earlier, but by now the rebellion had been contained and there was no need for reinforcements. This single message of only nine words saved the British government £60,000 - more than paying back its investment in the cable.

The Archimedes, used to lay the second cable, was the world's first propeller driven steam ship and was named appropriately after the Archimedes Screw. Built in 1839 by Henry Wimshurst, father of the inventor of the Wimshurst electrostatic generator, it was sixteen years before the launch of the similarly equipped Niagra which had been used to lay the first cable.

It was not until 1956, almost a hundred years after the original cable was laid, that the Atlantic was spanned by the first telephone cable TAT 1.

1858 German physicist Julius Plücker at Bonn University, looking for a way to observe "pure electricity" separate from the conductor carrying it, discovered cathode rays. Aware of Hauksbee's glow discharge demonstrations in 1705, he commissioned local glassblower Heinrich Geissler to construct an evacuated tube with a metal plate or electrode at each end. Plücker and his assistant Johann Hittorf evacuated the tubes using Geissler's "mercury air pump", which produced a much greater vacuum than Hauksbee had been able to achieve. They created an electric discharge between the electrodes and observed what happened in the intervening empty space. At first, with partial vacuum, the tube was filled with an eerie glow just as Hauksbee had found but as the vacuum was increased the glow disappeared and a different greenish glow appeared on the glass near one of the electrodes. Hittorf showed that the glow was due to invisible rays which he called glow rays (now called cathode rays) which were emanating from the other electrode. He noticed that they cast shadows when objects were placed in their way indicating that they travelled in straight lines and that they were deflected by magnets indicating that they were electrically charged.

On further investigation Plücker filled the tube with different rarified gases to observe how they conducted electricity and discovered that each gas glowed with a bright characteristic colour like modern day fluorescent lights, years before their time. Although this amazing nineteenth century invention was picked up by local shopkeepers to entertain their customers it was never commercialised and seems to have been forgotten until it was rediscovered by Claude in the twentieth century.

1858 Scottish linguist and chemist Archibald Scott Couper and German chemist Friedrich August Kekulé von Stradonitz of Czech decent simultaneously and independently recognized that carbon atoms can link to each other to form chains giving birth to the study of organic chemistry. Prior to this thinking, it was believed that molecules could only have one central atom. Couper's publication was delayed for three weeks by his reviewer Charles Adolphe Wurtz and all credit for the discovery went to Kekulé. Couper was devastated and never published another paper.

1858 The electric burglar alarm, invented five years earlier by Augustus Russell Pope, was first commercialised by American inventor Edwin Holmes who is usually credited with its invention. Holmes' workshop was later used by Bell in the development of the telephone and he was the first person to have a home telephone. Holmes' Burglar Alarm business was eventually bought by the American Telephone and Telegraph Company in 1905.

1858 Italian chemist Stanislao Cannizzaro, using Avogadro's theories, resolved the confusion between atoms and molecules of the compounds of the same atoms allowing a unified scale for relative atomic mass of the elements to be developed.

1859 Scottish engineer and polymath William John Macquorn Rankine published his "Manual of the Steam Engine and Other Prime Movers" in which he provided a systematic treatment of the theory of steam engines. Building on Carnot's theory on the efficiency of heat engines which was based on the thermodynamic cycle of a single gaseous phase reversible process, he recognised that the relationship does not apply if a phase change is encountered, because the heat added or removed during a phase change does not change the temperature of the working fluid. He therefore developed a more general theory of heat cycles for vapour based, closed systems in which the working fluid was alternately vaporised and condensed. Now known as the Rankine Cycle, it describes the steam cycle used in modern day electricity generating plants.

See also Heat engines.

1859 French inventor Ferdinand Carré developed the first gas absorption refrigeration system using gaseous ammonia which he patented in 1860. The system does not depend on a compressor and instead uses heat to change the vapour back to a liquid. Due to the toxicity of ammonia they were mainly used for the commercial production of ice rather than for domestic applications. Since gas absorption systems with no moving parts can be built, they are still used today portable applications where no electricity supply is available.

For an explanation of how heat is used for cooling see Refrigeration Systems in the section on Heat Engines.

1859 English naturalist Charles Robert Darwin published On the Origin of Species explaining his Theory of Evolution that all species are descended from common ancestors by Natural Selection. There had been many similar speculations in the past but coming from a respected scientist and justified by evidence, though not yet possible by experiment, it created widespread interest as well as controversy since its findings directly contradicted the Creationist Theory as found in the bible and traditionally held by the church.

It was the culmination of many years' work by Darwin. As a self funded naturalist with the aim of collecting specimens, in 1831 he accompanied captain Robert FitzRoy's expedition to chart the coastline of South America sailing on HMS Beagle as a passenger. The expedition was planned to take two years but lasted almost five years during which Darwin was seasick most of the time while at sea. In South America he gathered fossils of extinct species and discovered later that they were allied to other species still living on the same continent. He noticed that finches present on three of the Galapagos Islands represented three separate species each unique to that particular island, and speculated that "one species does change into another" by the genealogical branching of a single evolutionary tree. It was not until over twenty years later after much further research that Darwin eventually published his theories.

1860 Spurred by the threat of the Civil War, entrepreneurs William H. Russell, William B. Waddell and Alexander Majors launched the Pony Express mail service to bring faster communications to the American West. It consisted of relays of men riding horses carrying saddlebags of mail across a 2000 mile trail between St. Joseph, Missouri, and Sacramento, California. The journey took between ten and twelve days with the pony riders covering around 250 miles in a 24-hour day. Soon the Pony Express had more than 100 stations, 80 riders, and between 400 and 500 horses, becoming part of the legend of the Old West. Sadly, despite its fame, the service lasted only 19 months when the completion of the Pacific Telegraph line in October 1861 rendered its service obsolete and its investors bankrupt.

1860 Belgian engineer Jean Joseph Étienne Lenoir patented the first practical internal combustion engine, a single-cylinder, two-stroke engine which burnt a mixture of coal gas and air. It was a double acting configuration with the power stroke and exhaust stroke taking place simultaneously on opposite sides of the piston. The fuel/air charge was not compressed before ignition which was provided by a spark from a Ruhmkorff coil. His patent also included the provision of a carburettor so that liquid fuel could be substituted for gas. The thermodynamic cycle on which the engine was based is named the Lenoir cycle after him.

Lenoir went on to build an experimental vehicle driven by his gas-engine, which managed to achieve a speed of 3 kms/hour in 1862.

1860 Munich clockmaker Christian Reithmann was granted a patent for a four stroke internal combustion engine, but lost out to Otto in subsequent legal patent disputes. He is also reputed to be the first person to use Hydrogen to power an internal combustion engine.

1860 The Lead Acid battery, the first practical rechargeable storage battery was demonstrated by Raymond Gaston Planté. It used spiral wound electrodes of Lead and Lead Oxide immersed in Sulphuric Acid and despite delivering remarkably high currents it remained a laboratory curiosity for two decades until the manufacturability and performance were improved by Fauré. The reversible battery cell chemistry had been observed 60 years earlier by Gautherot using copper electrodes but he failed to realise the potential of his discovery. (Sorry!) After over 145 years of development, patents are still being awarded for improvements to this simple device. Currently the value of Lead Acid batteries sold every year in the world is over $30 Billion and still growing.

1860 Concerned with the security of coal supplies, French mathematician Auguste Mouchout started work on the design of a solar powered motor, the first practical application of solar energy. The following year he was granted a patent for his design which used sunlight to boil water in a solar boiler to raise steam to drive a conventional motor. By 1865 his efficiency improvements included solar collectors or reflectors to catch and focus more of the sun's energy and also a tracking device to maintain the optimum orientation towards the sun.

1860 Maxwell showed that white light can be generated by mixing only three colours not the full spectrum as indicated by Newton.

The following year he published "On the theory of primary colours" in which he explained that any colour, not just white light, can be generated with a mixture of any three primary colours. He chose red, green and blue and produced the world's first colour photograph at a demonstration of colour photography to the Royal Institution in London in 1861. The subject was a tartan ribbon. Three separate monochrome images were made by exposing the ribbon through red green and blue filters respectively to make three lantern slides. A colour image of the ribbon was then created by projecting the three images from the slides simultaneously on to a screen through three separate lanterns, each equipped with the same filter used to make its image. See Maxwell's Colour Photograph.

Maxwell also developed the colour triangle, a practical tool for generating any desired colour. The vertices of the triangle represent the primary colours and the proportions of each primary colour required to generate the desired colour are determined by the distance of the desired colour from each vertex.

Maxwell's work could be considered to be the basis for modern colorimetry. Colour television and HTML, the language used to generate the colours in Internet browsers, work on the principle of combining different proportions of red, green and blue primary colours (RGB) to produce the full spectrum of colours as proposed by Maxwell.

1861 German schoolmaster Johann Philipp Reis made the first public presentation of a working telephone to Frankfurt's Physics Association (Der Physikalische Verein) and published "Telephony Using Galvanic Current". His transmitter and receiver used a cork, a knitting needle, a sausage skin, and a piece of platinum. Initially fifty units were made but their performance was erratic. Unfortunately Reis suffered from tuberculosis and did not have the time nor the energy to perfect his invention which he called the "Telephon", nor did he find the time to patent it. He died at the age of forty.

1861 Italian immigrant to the USA, fugitive from persecution as a supporter of the Italian unification movement, Antonio Santi Giuseppe Meucci, after constructing numerous devices which enabled the transmission of sound, demonstrated a working telephone system in New York. It was based on a system he had devised for communicating between his bedridden wife's room and his workshop in the basement. He called it the Telettrofono and it was reported in the local Italian language newspaper "L'Eco d'Italia" at the time.

Meucci was perpetually short of cash. He was a prolific inventor but was unsuccessful in commercialising his ideas and this consumed most of his income. Nevertheless he also provided financial support to the leader of the Italian unification movement Giuseppe Garibaldi during his exile in the United States.

Meucci continued to devise improvements to his telephone system, including inductive loading (in 1870) to enable longer distance calls. Unfortunately, in 1871 when he was incapacitated with serious burns from an explosion aboard the steamship Westfield on which he was travelling, his wife sold all his early models of telephone devices for $6. Meucci could not afford the $250 needed to patent his system, however in 1871 he did manage to obtain a cheaper official "Caveat" stating his paternity of the invention. After the sale of the old prototypes, in 1874 he handed some new models to Western Union Telegraph for evaluation and these were subsequently seen by Alexander G.Bell who had access to the laboratory where they were stored. In 1876 he was surprised to read in the newspapers that Bell was credited as the sole inventor of of this amazing new device. United States Patent No. 174,465, issued to Alexander Graham Bell in 1876, became recognized as the world's "most valuable patent." Meanwhile Meucci died in poverty in 1989 bringing to an end the US Government's fraud proceedings against Bell.

Meucci was finally recognised as the first inventor of the telephone by the United States Congress in its resolution 269 dated June 15, 2002, 113 years after his death.

1861 French engineer Alphonse Beau de Rochas patented the four stroke cycle the principle on which most modern internal combustion engines depend though he never built an engine.

1862 German travelling salesman and inventor Nicolaus August Otto demonstrated the World's first successful four-stroke, spark ignition, internal combustion engine. Prior to that, three patents for four stroke engines had been awarded, the first to Italian inventors Eugenio Barsanti and Felice Matteucci in London in 1854, the second to German engineer Christian Reithmann in 1860 and the third to French engineer Alphonse Eugène Beau de Rochas in 1861 however none of these engines achieved commercial application and there is no evidence that Otto was aware of these developments. In 1864 with Eugen Langen the owner of a sugar factory, Otto established N.A. Otto & Cie. (today's DEUTZ AG) to manufacture the engines. Initially they made only stationary engines but today the Otto cycle, named after him, is the operating principle used by the vast majority of the world's piston engines.

See also Heat engines.

1863 The British government passes the Alkali Works Act setting limits to the emissions of noxious substances, one of the first attempts to recognise and control environmental pollution. Alkali compounds were widely used at the time in the production of glass, soap, and textiles and were manufactured using the Le Blanc Process whose byproducts included various harmful emissions including hydrochloric acid, nitrous oxides, sulphur and chlorine gas. As a result, manufacturing plants were ringed by dead and dying vegetation and scorched earth and local residents suffered health problems. The new law was backed by the appointment of Alkali Inspectors who monitored pollution levels.

One of the founders of modern chemical engineering was George E. Davis who started his career as an "Alkali Inspector". He stressed the value of large scale experimentation (the precursor of the modern pilot plant), safety practices, and a unit operations approach for controlling chemical manufacturing processes.

1863 Ányos Jedlik, then physics professor at the University of Pest in Hungary, introduced his multiplying capacitor battery in which a bank of electrostatic generators was used to simultaneously charge a parallel bank (battery) of capacitors. The charged capacitors were then switched to a series connection so that the voltage appearing on the output terminals was equal to the sum of the voltages on the individual capacitors, enabling very high voltages to be built up. He was awarded a gold medal at the 1873 Vienna World Exhibition for his design.

1864 Maxwell predicts that light, radiant heat, and "other radiations if any" are electromagnetic disturbances in the form of waves propagated through an electromagnetic field according to electromagnetic laws. It was not until 1873 that Maxwell provided the theoretical justification for his predictions.

1864 James Elkington the owner of a silver plating works in Birmingham, invented a commercial method for the refining of crude copper by the electrolytic deposition pure copper from a solution of copper salts. He patented the idea the following year and 1869 he founded the first electrolytic refining plant using this process, at Pembrey in South Wales.

1865 Clausius introduces the concept of entropy (from the Greek "transformation") defined as: "The internal energy of a system that cannot be converted to mechanical work" or "The property that describes the disorder of a system". He restated the Second Law of Thermodynamics, first outlined by Kelvin, in the context of system entropy as "In a closed system the entropy can only increase".

1865 French engineer Pierre-Émile Martin took out a license from German engineer, Karl Wilhelm Siemens and developed the open-hearth process in an attempt to circumvent the Bessemer patents. This process converts iron into steel in a broad, shallow, gas fired open-hearth furnace, by adding scrap iron including wrought iron or iron oxide as well as the alkaline limestone to molten pig iron until the carbon content is reduced by dilution and oxidation. The process allows for the production of larger batches of steel than the Bessemer process. It also allows precise control of the specifications of the steel but it is very slow.

See also Iron and Steel Making

1865 The International Telecommunications Union (ITU), the world's oldest international organization, an example of international cooperation at its best, was established to develop a framework agreement covering the interconnection of the first national and independent telegraph networks which at the time were built and operated to different and often incompatible standards. Its agreements cover interconnections, signalling and message protocols, equipment standards, operating instructions, tariffs, accounting and billing rules.

Today every telephone whether it is a new push button phone or an old dial phone, an analogue or digital cordless phone, a mobile phone, a payphone or a proprietary office system phone can be connected to every other telephone in the world. The same network is used to connect fax machines and the telephone message may be analogue or digital. The telephone message may be routed to an office in New York, a remote rural village in China or it can find the called party wherever they might be driving their car in Europe, passing through open overhead wires, underground cables, microwave links, fibre optic links, satellite links, undersea cables or local wireless links on the way. The signalling will be understood, the message will get through and the intermediate organisations carrying the call will get paid for their service.

With the advent of radio and later television, the ITU took on a similar role in managing the use of the radio spectrum, regulating frequency allocations, bandwidths and transmission powers to avoid the possible chaos of millions of transmitters from all over the world interfering with eachother. Despite the finite limitation on the available bandwidth, the ITU's regulatory framework also allows the flexibility to accommodate an ever growing number of users as well as new applications such as radar, cellular phones and GPS satellite navigation and the use of new modulation, multiplexing and transmission technologies as they have been developed to ensure the efficient use of this scarce resource.

The telephone network used to be the biggest machine in the world. Now with the advent of the Internet the machine is even bigger with computers as well as telephones connected together over the same network with modems carrying data and broadband terminals passing data, video and a host of new services down the same old wires and it still all works thanks to the ITU working anonymously in the background.

And all of this has been achieved with the ITU's recognition of "the sovereign right of each State to regulate its telecommunication"

See ISO and the Internet for how NOT to do it.

1866 Almost thirty years after Davenport had built the first practical electric motor using electromagnets in both the stator and rotor, the same technique was applied to the self energising dynamo. A wound rotating electromagnetic armature, replacing the weaker permanent magnet of the magneto, was invented almost simultaneously by Samuel Alfred Varley who's design was patented on 12 December 1866, by Werner Siemens who publicised his design on 17 January 1867, and by CharlesWheatstone who presented a paper to the Royal Society on 4th February 1867 about the principles involved. The design permitted much more powerful and efficient DC generators.

It was later revealed that a patent had been granted in 1854 to Mr. Soren Hjorth, a Danish railway engineer and inventor for a similar invention with self excited armature coils. Hjorth's patent is to be found in the British Patent Office Library.

The principle had also been demonstrated by Hungarian priest Ányos Jedlik in 1861.

The advent of practical dynamos provided a convenient, low cost, inexhaustible source of electric power overcoming many of the limitations of the battery and marked the beginning of electricity generation by electromechanical means rather than by electrochemistry. Rotary generators paved the way for the widespread use of electricity for both high power industrial applications and for consumer appliances in the home.

1867 The reversibility of the dynamo was enunciated by Werner Siemens but it was not demonstrated on a practical scale until 1873 by Gramme and Fontaine.

1867 Kelvin presented to the Royal Society, a paper "On a self-acting apparatus for multiplying and maintaining electric charges, with applications to illustrate the voltaic theory" describing a water powered electrostatic generator.

1867 The first practical typewriter was invented by Milwaukee newspaper editor Christopher Latham Sholes and his colleagues, Carlos Glidden and Samuel W. Soule. Sales did not immediately take off and early designs suffered from clashing and jamming of the keys when fast typing was attempted. At the suggestion of Sholes' financial backer, James Densmore, Scholes re-laid out the keyboard, into what eventually became the familiar QWERTY layout by spacing out pairs of keys which are often used together to avoid jams by effectively slowing down the typist.

Commercial success eventually came when the patents, manufacturing and sales rights were sold to the Remington Arms Company where the design continued to undergo many engineering improvements. One of the innovations was a minor keyboard layout change to replace the "period" key, previously allocated a place on the top row, with the "R" key so that their brand name "TYPE WRITER" could be typed out from the keys in only one row of the keyboard.

In return for the rights they obtained, Remington offered Scholes and Densmore either cash or royalties from future sales. Scholes took the cash, $12,000, a considerable sum in those days. Densmore took the royalties and eventually received $1.5 million.

1868 Invention of the Leclanché cell carbon-zinc wet cell by the French railway engineer Georges Leclanché. It used a cathode of manganese dioxide mixed with carbon contained in a porous pot and an anode of zinc in the form of a rod suspended in an outer glass container. The electrolyte was a solution of ammonium chloride that bathed the electrodes. The manganese dioxide acts as a depolariser absorbing hydrogen gas released at the cathode. The first practical battery product to be commercialised, it was immediately adopted by the telegraph service in Belgium and in the space of two years, twenty thousand of his cells were being used in the telegraph system. Later, it was also Alexander Graham Bell's battery of choice for his telephone demonstrations. Domestically however its use for many years was limited to door bells.

Leclanché's electrochemistry was implemented with a different cell construction by Gassner in 1886 to make more convenient dry cells which still survive today in the form of zinc-carbon dry cells, the lowest-cost flashlight batteries. Polaroid's PolaPulse disposable batteries used in instant film packs also used Leclanché chemistry although in a plastic sandwich.

1868 Maxwell analysed the stability of Watt's flyball centrifugal governor. Like Airy, he used differential equations of motion to find the characteristic equation of the system and studied the effect of the system parameters on stability and showed that the system is stable if the roots of the characteristic equation have negative real parts. He thus established the theoretical basis of modern feedback control systems or cybernetics.

1868 French engineer Jean Joseph Farcot patented improvements to machine control and in 1873 published a book entitled Le Servo-Moteur introducing the notion of servomechanisms which allow a small control system to control pieces of far heavier machinery.

1869 Prussian physicist Johann Wilhelm Hittorf published his laws governing the migration of ions. These were based on the concept of the transport number, the rate at which particular ions carried the electric current, which he had previously developed. He had noted in 1853 that some ions traveled more rapidly than others. By measuring the changes in the concentration of electrolyzed solutions, he computed from these the transport numbers (relative carrying capacities) of many ions.

1869 German chemist Julius Lother Meyer discovered the periodic relationship between the elements by plotting a graph of atomic weight against atomic volume, however its publication was delayed by the reviewer.

Working at the same time, this periodic relationship was also noticed by Russian chemist Dimitri Ivanovich Mendeleyev. By arranging cards with the names, atomic weights and some properties of the 65 known elements at that time, into rows and columns he noticed an underlying pattern. His Periodic Table of the elements was published before Meyer's and the Periodic Table thus became attributed to Mendeleyev. Since then over 700 versions of the table have been produced.

Gaps in the table led scientists to speculate on the existence of hitherto unknown elements with predicted properties related to their positions in the table. The existence and properties of these elements was duly confirmed once suitable experiments could be devised.

1869 French paper manufacturer Aristide Berges built the first hydroelectric generator at Lancey near Grenoble. Using sluice gates or penstocks, he directed water from a 200 metre high Alpine waterfall through a waterwheel which drove an electrical machine generating 1.5 kiloWatts of power. He coined the expression hydroelectric power. Over the years Berges built bigger machines and 1886-1887 he built the world's first hydraulic accumulator.

1869 John Tyndall explained that the reason why the sky is blue is because of the scattering of light by dust and large molecules in the upper atmosphere, now known as the Tyndall Effect. He noticed that most light wavelengths pass through the atmosphere unaffected, but the wavelength of blue light is comparable with the spacing of the molecules in the atmosphere which therefore tends to be scatter the Sun's blue light. The effect is more commonly known as Rayleigh scattering, after Lord Rayleigh, who studied it in more detail some years later.

1870 New Yorker John Wesley Hyatt patented the first synthetic plastic, now called Celluloid, which was invented by Parkes in1855. He first used it as a coating for billiard balls and later for denture plates.

1870 John Player developed a process of mass producing strands of glass with a steam jet process to make what was called mineral wool for use as an effective insulating material. (Editor's Note - I have not yet been able to verify this first statement which could be an oft repeated internet myth related to the next paragraph. Please email me if you can help. The next statement is true.)

John Player had no connection with John Player cigarettes, a major brand in the 1980's. Nevertheless an unfounded rumour spread in the late 1980's and early 1990's, no doubt encouraged by their competitors, that the filters in John Player cigarettes contained fibreglass resulting in major damage to their market share.

1870's Austrian physicist Ludwig Eduard Boltzmann published a series of papers developing the theory of statistical mechanics with which he explained and predicted how the properties of atoms such as mass, charge, and structure determine the visible properties of matter such as viscosity, thermal conductivity, and diffusion. He showed that the kinetic energy of a molecule of an ideal gas is proportional to its absolute temperature. The ratio is equal to 1.38 X 10-23 Joules per degree Kelvin (J/K) and is called the Boltzmann Constant in his honour.

Boltzmann also derived a theoretical relationships for the thermodynamic entropy of a gas. 70 years later Shannon used an equivalent relationship to define the information entropy in a message.

Tragically ill and depressed, Boltzmann took his own life in 1906.

1871 Weber proposed the idea for atomic structure that atoms contain positive charges that are surrounded by rotating negative particles and that the application of an electric potential to a conductor causes the negative particles to migrate from one atom to another creating current flow.

1871 German scientist Steiner revived an apparently dead patient by passing a weak electrical current directly through his heart. The first recorded use of electric shock treatment for reviving people after cardiac arrest.

1871 After witnessing a death from smoke inhalation, John Tyndall invented the fireman's respirator or gas mask. See also Stenhouse

1872 PVC, Poly Vinyl Chloride first created by German chemist Eugen Baumann. It was not patented until 1913. In 1926 Waldo Semon invented a new way of making PVC into a useful product and he is now generally credited with discovering it.

1872 One of the many "Fathers of Radio" West Virginian dentist Mahlon Loomis was granted a patent for "a new and Improved Mode of Telegraphing and of Generating Light, Heat, and Motive Power". Although not a true radio system it was an attempt at making a wireless telegraphy system by replacing the batteries with electricity gathered from the atmosphere by means of flying kites attached to long copper wires. It used a Morse key between one kite wire and the ground to send signals and at the remote kite it used a galvanometer between the wire and the ground to detect the signals. It is claimed that signals using this method were transmitted over 14 miles, however it is questionable whether this system ever worked and it was never commercially exploited. Nevertheless the Guinness Book of Records credits Loomis with sending the first signals through the air. It was another sixteen years before Hertz demonstrated the existence of radio waves.

1872 American telecommunications engineer Joseph Barker Stearns of Boston developed the first practical telecommunications duplexing system. He accomplished this by using two different types of signals, one for each direction. In one direction he used varying strength signals (e.g. On or Off) which he detected with a common or neutral relay, while in the opposite direction he used varying polarity signals (Plus or Minus) which he detected with a polarised relay. The receivers were designed to respond only to signals of the appropriate type from the remote transmitter and to ignore local transmissions. Stearns' system effectively doubled the capacity of the installed telegraph lines and Western Union rapidly acquired rights to use it.

1872 British electrical engineer Josiah Latimer Clark invented the Clark Standard Cell which provided a reference voltage of 1.434 volts at 15 °C. The cathode was Mercury, in contact with a paste of Mercurous Sulphate, and the anode was Zinc amalgam in contact with a saturated solution of Zinc Sulphate.

1872 American mechanical engineer George Brayton patented his Ready Motor, a continuous combustion, two cylinder, two stroke, kerosene (paraffin) engine. It used a rocking arm coupled to a flywheel to drive the pistons alternately up and down. One piston was used to compress the air which was then mixed with a controlled amount of fuel and ignited by a continuous flame in a combustion chamber and fed into the second chamber where the hot gases expanded providing the power stroke. The modern gas turbine uses the same three fundamental components of Brayton's system, a compressor, continuous combustion burner and an expansion chamber from which work can be extracted and the thermodynamic cycle on which it based, heat addition at constant pressure, is now called the Brayton cycle. Brayton himself never made anything other than piston engines.

See also Gas turbines and Heat engines.

1873 Scottish physicist James Clerk Maxwell published his "Treatise on Electricity and Magnetism" in which, using a water analogy, he distilled all electromagnetic theory into a set of four rules now accepted as one of the fundamental laws of nature. Now known as Maxwell's Equations, they were one of the most important scientific works of the century, not only explaining all electric, magnetic and radiation phenomena known at the time but also providing the foundations for the two great theoretical advances of the twentieth century, relativity and quantum theory.

Maxwell's four equations express, respectively:

  • How electric charges produce electric fields - Gauss' law.
  • The absence of single magnetic poles.
  • How currents produce magnetic fields - Ampere's law with an additional term called the displacement current showing that a changing electric field is equivalent to a current also inducing a magnetic field.
  • How changing magnetic fields produce electric fields - Faraday's law of induction.

In mathematical vector form these complex relationships can be expressed very simply as:-


∇• D = ρ

∇• B = 0

∇x H = J + δD/δt

∇x E = - δB/δt

ρ is the free electric charge density (not including dipoles)
D is the electric displacement field or flux density = ε0E
B is the magnetic flux density = µ0H
H is the magnetic field
J is the current density
E is the electric field
∇• is the divergence operator
∇x is the curl operator
ε0  is the electric permittivity of a vacuum
µ0  is the magnetic permeability of a vacuum

Maxwell originally expressed his theory in 20 partial differential equations. They were subsequently simplified in 1884 by Oliver Heaviside who expressed them in vector form which is the form in which they are shown above.

As some physics teachers are fond of saying:

"The Lord said Let there be light and there were Maxwell's equations"

These four equations provided the theoretical justification of his 1864 predictions of the existence of radiation or electromagnetic (radio) waves, even though at that time there was still no evidence to demonstrate that such a phenomenon existed.

Maxwell showed that electromagnetic fields hold energy which is in every way equivalent to mechanical energy and that a changing magnetic field will induce a changing electric field which in turn induces a changing magnetic field, and so on, such that an electromagnetic wave is created in which the energy oscillates between the electric and magnetic fields.

He also showed that neither the electric wave nor the magnetic wave can exist alone. They travel together, always at right angles to, and in phase with eachother.

The velocity of propagation of the electromagnetic wave v can also be derived from Maxwell's equations as v = E/B the ratio between the electric field strength E and magnetic flux density B which is also equal to 1/√µ0ε0. From a knowledge of the magnitudes of µ0 and ε0 he determined that the velocity of propagation of the electromagnetic wave is constant and equal to the speed of light and that light is an electromagnetic wave.

It is a measure of Maxwell's genius that with four elegant and concise equations he could not only account for the movement of a compass needle next to a current carrying wire but with the same equations he was also able to predict, understand and correctly characterise mathematically such a complex phenomenon as electromagnetic radiation that nobody had yet witnessed or even imagined.

Maxwell was initially encouraged and supported in his theories by Kelvin, upon whose earlier work he built, however in his lifetime Kelvin never accepted Maxwell's conclusions believing them too theoretical and not related to reality.

It was 1888 before his predictions were proved right by experiments carried out by Heinrich Hertz.

In the twentieth century, while Einstein's relativity theory required Newton's laws to be modified, Maxwell's equations remained absolute.

See more about Electromagnetic Radiation and Radio Waves today.

Maxwell also introduced statistical methods into the study of physics, now accepted as commonplace and made significant contributions to structural analysts, feedback control theory (cybernetics) and the theory of colour taking the first ever colour photograph.

Maxwell was a kind and modest man, universally liked. His ideas were ahead of his time but he made no attempt to promote his work. Despite his monumental achievement, it was Hertz' name rather than Maxwell's that has become associated with radio waves and radio propagation.

He died of stomach cancer in 1879 at the age of forty eight without seeing the experimental confirmation of his theories.

Like several Victorian scientists, Maxwell used poetry to describe his interests and his work. 43 of his poems on such riveting subjects as "A Problem In dynamics", "British Association, Notes Of The President's Address", "To The Committee Of The Cayley Portrait Fund" and "Torto Volitans Sub Verbere Turbo Quem Pueri Magno In Gyro Vacua Atria Circum Intenti Ludo Exercent" about spinning tops, were published in 1882, after his death, by his friend Lewis Campbell.

Quotations about Maxwell:

When Michael Faraday was asked what was his greatest ever discovery he replied "James Maxwell"

"The Special Theory of Relativity owes its origins to Maxwell's Equations of the Electromagnetic Field" - Albert Einstein.

"Ten thousand years from now, there can be little doubt that the most significant event of the 19th century will be judged as Maxwell's discovery of the laws of electrodynamics" - Richard Feynman

1873 Belgian carpenter and instrument maker Zénobe Théophile Gramme in partnership with French engineer and inventor Hippolyte Fontaine developed the first reliable commutators for DC machines. (The commutator is the device which reverses the current in the rotor coil as it passes from the influence of one magnet pole to the next magnet pole of opposite polarity in order to maintain a unidirectional current in the external circuit).

They also demonstrated the reversibility of their dynamo by pumping water at the Vienna International Exhibition using two dynamos connected together, one, the generator, deriving motion from a hydraulic engine, provided electrical power to the receiving dynamo which worked the pump. It is said that they discovered the phenomenon by accident when an idle dynamo was mistakenly connected across another working/running dynamo and began motoring backwards. They did however realise that the importance of their discovery was not just the reversibility of the dynamo, but also the possibilities electrical power transmission. The fact that electrical power could be generated in one place and used in another.

1873 The first demonstration of electric traction in a road vehicle by Robert Davidson in Edinburgh using iron/zinc primary cells to drive a truck.

1873 English telegraph engineers, Joseph May and Willoughby Smith, while working with Selenium, noticed that its conductivity changed under the influence of light thus discovering the photoconductivity effect.

1873 Dutch physicist Johannes Diederik van der Waals deduced more accurate gas laws taking into account the volume of the actual molecules making up the gas and the intermolecular forces between them. The van der Waals forces, named after him, assumed that neutral molecules behaved like dipoles with a positive charge on one side and a negative charge on the other because their shape was distorted. The true nature of the forces was later explained in 1930 by Polish-born physicist Fritz London using quantum theory.

Van der Waals was awarded a Nobel Prize in 1910 for his work on the equation of state for gases and liquids.

1874 A thermo-electric battery based on the Seebeck effect powered by a gas heater introduced by M Clamond in France. Known as the Clamond pile or thermopile, it consisted of a stack of circular arrays of junctions of iron with a zinc-antimony alloy heated by a gas burner located in the centre of the stack. It generated 8 Volts providing a current of 2 to 3 Amps and supplied both heat and electricity to galvanising baths.

1874 Thomas Alva Edison invented the quadruplex telegraph, which was capable of sending four Morse coded messages simultaneously on a single channel. He amalgamated and rearranged the duplexer of Gintl, and Farmer and the diplexer of Stearns into a single system permitting two messages to be sent in each direction. As with Gintl's duplexer design, two relays in each terminal were unresponsive to outgoing signals, one of these relays responded to current increases of the incoming signals the while the other responded to current reversals of the received signals. Thus Stearns duplexing method of distinguishing between two signals was modified by Edison to separate the signals going in the same direction (diplexing) rather than in opposite directions (duplexing). This avoided the problem of synchronising the receivers with the transmitters. The quadruplex allowed the telegraph lines to carry four times the traffic and saved the telegraph companies millions of dollars.

Edison had started the development of his quadruplex system in 1873 in cooperation with Western Union using their facilities for his experimental work. He had agreed with William Orton, the president of Western Union, a development fee and that the patents for the design would be assigned to Western Union. When the design was complete Edison was given $5000 as part payment and $25,000 later. Orton also authorised a royalty payment to Edison of $233 per year before leaving on a business trip. While he was away, Edison was approached by George Jay Gould, railroad baron, Wall Street financier, stock manipulator and head of Atlantic and Pacific Telegraph Company, an arch rival of Western Union. He offered Edison $30,000 cash for the quadruplex patents and a job at Atlantic and Pacific. Edison accepted and wrote to Orton saying their arrangement had been a mistake and he revoked the assignment of patents to Western Union. Edison had sold the patents twice over. This earned him the title of "Master of Duplicity and Quadruplicity" bestowed on him by New York journalists. There followed years of litigation which only ended with the eventual amalgamation of the two telegraph companies. A portent of Edison's business methods to come. See Edison and Tesla.

Quadruplex telegraphs were eventually displaced by two new inventions, Baudot's multiplex telegraphy capable of eight or more simultaneous transmissions (see next) and Murray's teleprinter machines which did not use Morse code.(See following entry - Baudot code).

Edison set up his first small laboratory and manufacturing facility in Newark, New Jersey in 1871 to produce new designs for Western Union and others. In 1876 he moved to a larger facility at Menlo Park equipped to work on any invention opportunities he might turn up. This was the world's first industrial research and development facility and was where Edison's phonograph, light bulb and electrical power systems were developed. See more about Edison's Inventions.

1874 Jean Maurice Émile Baudot, an officer of the French Telegraph Service made major improvements in the telegraph system by bringing together the five unit code devised by Gauss and Weber, now called the five bit Baudot code, and the synchronous time division multiplex (TDM) system, proposed by Farmer in 1852, into a practical design for a printing telegraph.

The five bit code was the first truly digital code, each unit having only two logical states, giving 32 possible combinations or characters, the shortest practicable code for the number of characters to be transmitted. Baudot used two special characters to switch between letters and numbers giving effectively 64 combinations, enough to allow for 26 characters for the alphabet and 10 numbers plus other miscellaneous punctuation and synchronisation codes. Input was by 5 keys. Later adaptations by Murray in 1903 (and others) used five hole punched tape to input the characters with a sixth row of smaller holes to feed the tape through the reader. The tape had the advantage that it could be punched off line and subsequently transmitted at high speed, but more importantly the tapes enabled the transmission speed to be controlled thus facilitating the multiplexing. Early teletypewriters also used Baudot code which eventually supplanted Morse code as the most commonly used telegraphic alphabet becoming known as the International Telegraph Code No.1.

Although the code is now named after Baudot, the five digit binary code was first proposed by Francis Bacon in 1605.

The Baudot distributor enabled four messages to be transmitted simultaneously. Multiplexing was achieved by using synchronised motors at either end of the line with brushes which connected each channel sequentially, for a fixed interval, to a single transmission line as the motor rotated. Synchronisation codes were sent down the line to keep the transmitter and receiver in step.

In modern circuits TDM is accomplished by interleaving the bit streams from the different channels.

The unit of measurement for data transmission rates of one character per second is named the Baud, a shortened form of Baudot, in his honour.

1874 German physicist Karl Ferdinand Braun discovered one way conduction in metal sulfide crystals. He later used the rectifying properties of the galena crystal, a semiconductor material composed of lead sulfide, to create the crystal detector used for detecting radio signals which Braun worked on with Marconi. Thus was born the first semiconductor device. Now called the diode, the cat's whisker detector was rediscovered and patented 30 years later by Pickard and Dunwoody.

1874 Irish physicist George Johnstone Stoney expanding on Faraday's laws of electrolysis and the notion that an electric charge was associated with the particles deposited on the electrodes during electrolysis, proposed that the minimum unit of charge was that which was found on the hydrogen ion and that it should be a fundamental unit. He named it the "electrine". In 1891, he changed the name to "electron". He calculated the magnitude of this charge from data obtained from the electrolysis of water and the kinetic theory of gases. The value obtained later became known as a coulomb. Stoney was unaware of the nature of the atom and "Stoney's electron" is a unit of charge, not to be confused with J.J. Thomson's sub atomic particle which Thomson called a corpuscle but which we now call the electron.

1874 David Salomons of Tunbridge Wells, England demonstrated a 1 H.P. three wheeled electric car powered by Bunsen cells.

1875 American physicist Henry Augustus Rowland was the first to show that moving electric charge is the same thing as an electric current.

He built up an electrostatic charge on a rotating gramophone (phonograph) record by rubbing it with woolen cloth. A magnetic compass bought in close to the spinning disk was deflected, the magnitude of the deflection increasing with the speed of the disk. This showed that a magnetic field is not only set up by a current moving through a wire but also by a moving electrostatic field.

1876 On March 10 in Boston, Massachusetts, Alexander Graham Bell, a Scottish emigré to the USA, invented the telephone. Bell filed his application just hours before his competitor, American inventor Elisha Gray, founder of Western Electric, filed notice with the same patent examiner, an outline of a telephone he planned to patent himself. What's more, neither man had actually built a working telephone. Bell in particular did not have a working microphone but he made his telephone operate three weeks later using the microphone described in Gray's Notice of Invention, and methods Bell did not propose in his own patent. Being a "system" using several technologies over which Bell claimed sole rights, it spawned more than 600 law suits mostly focused on whether the concept of modulating a DC current supplied by a battery was revolutionary or insubstantial and which of the many rivals had thought of it first. Legitimate claimants included Belgian experimenter Charles Bourseul (1854), German schoolmaster Johann Philipp Reis (1861) and impoverished Italian US immigrant Antonio Meucci (1861) to whom the idea is now officially credited by the American Congress (disregarding the prior work of Reis).

Bell's United States Patent No. 174465 became recognized as the world's most valuable patent.

Similar controversies surround the invention of radio, but that's another story.

In an attempt to find an assassin's bullet lodged in the body of US President James Garfield, in 1881 Bell hastily devised a crude metal detector based on the induction balance recently devised in 1879 by David Hughes. It worked but it didn't find the bullet, indicating that it was deeper than at first thought. It was later discovered that the detector had been confused by the newly invented metal bed springs under the mattress on which the President lay. (The President died after eighty painful days from complications arising from contamination of, and further damage to his wound by the dozen or more doctors probing his body in search of the bullet).

Bell's father, grandfather, and brother had all been associated with work on elocution and speech, and both his mother and wife were deaf, profoundly influencing Bell's life's work. It was his research on hearing, speech and sound transmission which eventually led him to the invention of the telephone.

In 1877 Bell married Mabel Gardiner Hubbard, a student from his school for the deaf, the daughter of Boston lawyer Gardiner Greene Hubbard. Hubbard senior, helped Bell set up the Bell Telephone Company with himself as president ably defending the company from the avalanche of lawsuits it faced.

In later life Bell moved to the relative seclusion of his estate in Nova Scotia where he declared himself to be sick of the telephone which he regarded as a nuisance, referring to it as a "beast". He crusaded tirelessly on behalf of the deaf and worked on a variety of projects including flight and aerofoils. At odds with his genuine concern for the deaf, he was an advocate of eugenics and carried out experiments with sheep. He was convinced that sheep with extra nipples would give birth to more lambs, and built a huge village of sheep pens, spending years counting sheep nipples, before the US State Department announced that extra nipples were not linked with extra lambs.

1876 Welshman Sidney Gilchrist Thomas discovered that adding a chemically basic (alkaline) material to the Bessemer converter can draw phosphorus impurities from the pig iron into the slag which is skimmed off, resulting in phosphorus-free steel. This process was called the "Basic" Bessemer Process. Phosphorus makes the steel very brittle and up to that time it had been necessary to use costly phosphorus free ores from Wales and Sweden to produce the high quality steel. Thomas's innovation meant that iron ore from anywhere in the world could be used to make steel resulting in significant savings in production costs.

See also Iron and Steel Making

1877 The telephone industry created the next major leap forward in the demand for batteries.

In Bell's original 1876 system the microphone was a passive transducer in which the acoustic power of the human voice provided the energy to create the varying electric currents which represent the sound and also to carry them down the wire to the receiver. In Bell's microphone, or transmitter in telephone parlance, sound waves impinge upon a steel diaphragm causing it to vibrate in sympathy. The diaphragm is arranged adjacent to the pole of a bar electromagnet and acts as an armature. The vibrations of the diaphragm cause very weak electrical impulses to be induced in the coil of the electromagnet. However these feeble signals were quickly attenuated as they passed down the telephone line until they were inaudible, severely limiting the range of the circuit and hence the potential of the telephone system.

During 1877 and 1878 German born American Emil Berliner, David Hughes, Thomas Edison, Bell employee Francis Blake and English curate Henry Hunnings, were each working independently on designs for improved microphones based on active transducers in which the acoustic power controls an external source of power. An active transducer provides an electrical signal with about a thousand times more electrical power than the acoustical power absorbed by the transducer and their designs considerably improved the range of the telephone at the expense of requiring power from a local battery. They all used variants of a carbon transducer which depend on the fact that the electrical resistance of some materials varies with the physical pressure exerted on it, various forms of carbon material, such as carbon granules, coke or lamp black being particularly sensitive. In the carbon microphones which they developed, during the call the battery current flows constantly in a closed circuit across a capsule of carbon material between two terminals one of which is a flexible diaphragm. The sound pressure variations are transferred to the carbon by the diaphragm thus causing the battery current to vary in response to the sound pressure. Edison's design used lamp black and had the added refinement of an induction coil or step up transformer which superimposed the sound information from the transducer on to a separate higher level DC current flowing through the secondary winding of the coil in the main transmission line so that an amplified signal appeared across the terminals of the secondary coil and the stronger DC current carried it further. A process we now call modulation.

Rather than patenting his ideas for the microphone, Hughes, who was already wealthy from his invention in 1855 of the printing telegraph, communicated his designs to the Royal Society in the February 1878 and generously gave the carbon microphone to the world. This earned him the wrath of Thomas Edison who laid claim to the invention, accusing Hughes of plagiarism and patent infringement. Two months later Berliner and Edison filed for patents on carbon microphones within two weeks of each other resulting in numerous bitter law suits which were eventually settled out of court. Hunnings patented the idea of using carbon granules which could carry higher currents but his patent was challenged by Edison's lawyers. Being a man of limited means he conceded and sold the rights for £1000 and went on Edison's payroll. Berliner went to work for Bell who bought his design for $50,000 and Edison's design, based on principles described by Hughes but using Hunnings' crushed carbon granules became the basis of the standard telephone transmitter and with a few refinements was used for over a hundred years.

Berliner went on to found Deutsche Grammophon Co. and his trademark image became a painting by English artist Mark Barraud of his dog "Nipper" listening to His Master's Voice for which Barraud was paid £50 for the painting and a further £50 for the full copyright. Berliner's other notable invention was the gramophone using a flat disk instead of the cylinder used by Edison.

1877 English experimenter Williams Grylls Adams and his student Richard Evans Day discovered that an electrical current could be created in Selenium solely by exposing it to light and produced the first Solar Cells naming the currents produced this way photoelectric. Although the effect was attributed to the properties of Selenium it was in fact due to the properties of the junction between the Selenium, now known to be a semiconducting material, and the Platinum metal used to create the connection for measuring the current.

Note: Confusingly the currents produced by solar cells, named photoelectric currents by Adams and Day, do not arise from the photoelectric effect in which light causes electrons to be emitted from the surface of the material by the process of photo-emission. Solar cells or photovoltaic cells are made of semiconductor material. The incoming light (photons) moves electrons from the valence band across the band gap to the conduction band and the resulting electron-hole pairs cause an internal electrical field to be set up across the P-N junction which separates them. In this way different charges on the two electrodes of the solar cell are created, and this potential difference can be used to drive a current through a wire.

It was not until 1954 that the efficiency of photovoltaic cells was improved enough to generate useful power.

1877, German, Ernst Siemens patented the first loudspeaker before the advent of electrical music reproduction.

1878 Electric alternator invented by Gramme and Fontaine.

1878 American physical chemist Josiah Willard Gibbs developed the theory of Chemical Thermodynamics introducing the free energy concept. When a chemical reaction occurs, the free energy of the system changes. The free energy is the amount of energy available to do external work, ignoring any changes on pressure or volume associated with the change of state. Thus the change in Gibbs free energy represents the total useful energy released by the chemical action which can be made available for doing work. When the free energy decreases, the entropy always increases, and the reaction is spontaneous. (The value of the free energy lies in the fact that its change is easier to measure than the change in entropy.)

He also developed fundamental equations and relationships to calculate multiphase equilibrium and the phase rule which specifies the minimum possible number of degrees of freedom, or variables such as temperature, pressure, concentration etc. in a (closed) system at equilibrium which must be specified , in terms of the number of separate phases and the number of chemical constituents in the system, in order to completely describe the state of the system. Gibbs' work laid the foundations for the theoretical representation of the energy transfers involved in chemical reactions. This allowed the performance (energy release) of galvanic cells to be quantified and predicted.

He published his work in the Transactions of the Connecticut Academy of Arts and Sciences, an obscure publication, published by his brother in law, with a very limited, mostly local, circulation. His work on thermodynamics, a major advance in the understanding of chemical reactions, therefore remained unknown until 1883, when Wilhelm Ostwald a Russian-German physical chemist discovered it and translated it to German.

In 1881 Gibbs published "Elements of Vector Analysis" which presents what is essentially the modern system of vector analysis. It permitted the presentation and analysis of complex relationships between multi-dimensional forces such as Maxwell's field theory to be simplified by the use of Gibbs' vector notation and methods. He also made important contributions to the electromagnetic theory of light. His later work on statistical mechanics was also important, providing a mathematical framework for quantum theory.

For all his major contributions to science, Gibbs was a modest man like Maxwell who shunned fame and fortune, living a quiet and contented, simple life as a bachelor, much admired by his students at Yale where he worked.

1878 French electrician, Alfred Niaudet, published "Traité élémentaire de la pile électrique" on electric batteries in which he described over a hundred different battery types and combinations of elements, indicating the growth and importance of battery technology.

Niaudet described the various chemical mixes and designs which had been used to address a range of design goals. The polarisation problem was solved by using non polarising chemical mixes which did not produce gases, or by using mixes which included depolarising agents or oxidants, which reduced any hydrogen emissions by combination with oxygen. Other recipes were used to achieve higher cell voltages, higher capacity, lower costs or longer life. Alternative constructions were designed to improve the convenience of use and current carrying capability or to reduce the cell's internal resistance. Later the possibility of electrical recharging became a design aim.

Examples not mentioned elsewhere on this web site are given below.

Non polarising 2 Volt primary cells were mostly based on potassium dichromate and often used two electrolyte gravity cells (See below). Examples were:

  • 1840 Grenet's single electrolyte potassium dichromate "Bottle" cell with adjustable carbon and zinc electrodes, favoured by Edison for his domestic lighting systems.
  • Voisin and Dronier's potassium dichromate "Bottle" cell, a variation on the Grenet cell with different electrode controls.
  • 1842 Poggendorff 2 electrolyte cell, similar to the Bunsen cell but with potassium dichromate replacing the nitric acid.
  • 1852 John Fuller's patented "gravity cell" which had a zinc cathode whose base was immersed in liquid mercury, in a porous container with a dilute sulphuric acid solution. The anode was carbon, surrounded by orange-red potassium dichromate solution and crystals, again in sulphuric acid. Similar cells were patented by Leffert. The following year Fuller improved on Daniell's original design to provide the Daniell cell chemistry as we know it today by replacing the aggressive sulphuric acid electrolyte with the more benign zinc sulphate prolonging the life of the cell. He also used the gravity cell construction and the design became very popular for telegraph applications.
  • 1854 Gravity cell proposed by C. F. Varley
  • Radiguet 2 electrolyte cell with electrodes of mercury and zinc and electrolytes of sulphuric acid and potassium dichromate.
  • Guiraud 2 electrolyte cell, a low cost cell with electrodes of carbon and zinc and electrolytes of brine and potassium dichromate

Potassium dichromate is strongly toxic and these cells consequently fell into disuse.

Gravity cells are two electrolyte cells which depend on a lighter electrolyte, such as zinc sulphate, floating on the top of a heavier electrolyte, such as copper sulphate, like oil and water. Normally, diffusion would soon mix the two liquids destroying the cell's efficacy, but if a current was drawn continuously the natural migration of the ions kept the electrolytes apart. This construction reduced the internal resistance of the battery by eliminating the porous pot from the current path. Gravity cells were used extensively in the telegraph and telephone industry, however the inconvenience of keeping the cells undisturbed to avoid mixing the electrolytes and also above freezing temperatures eventually led to their replacement.

Gravity cells which used zinc electrodes suspended in zinc sulphate or sulphuric acid were also called Crowfoot Cells because the shape of the zinc electrode resembled the bird's foot.

Other non polarising primary cells such as the Daniell cell were two electrolyte cells based on copper sulphate and sulphuric acid electrolytes. These included designs by the following inventors

  • Smée whose cell was the fore-runner of this class. It used zinc and copper electrodes and the copper electrode was coated with finely-divided platinum intended to cause the evolved hydrogen to form bubbles and detach themselves. An imperfect solution, but the cell was nevertheless popular in the electroplating industry.
  • Carré who replaced Daniell's porous pot with a parchment membrane.
  • Callaud, who in the 1860's, eliminated the porous cup in the Daniell cell perfecting the gravity cell construction.
  • Hill similar to the Callaud cell.
  • Meidinger whose design was popular in Germany. It used the Callaud chemistry but with a construction which was much easier to maintain.
  • Verité
  • Minotto who developed a gravity cell in 1862, based on Daniell's chemistry, for tropical use. It was used by the Indian PTT.
  • Essick whose cell was designed to operate at 70°C to achieve higher current outputs.
  • Tyer who patented a mercurial battery with silver and mercury-covered zinc in dilute sulphuric acid.

These cells all produced only 1 Volt which made them less attractive than the 2 Volt dichromate cells.

Many batteries at that time used elemental mercury for contacts or for preventing local action at the zinc electrodes. Impurities in zinc, such as iron or nickel, effectively created minute short-circuited cells around each grain of impurity which soon ate away the zinc. Pure zinc was far too expensive to be considered at that time, however in 1835 William Sturgeon discovered that the local action in the cheaper impure zinc could be eliminated if the zinc electrodes were amalgamated with liquid mercury.

In 1840 Sturgeon developed a long lasting battery consisting of a cast iron cylinder into which a rolled cylinder of amalgamated zinc was placed. Discs of millboard were used as separators and the electrolyte was dilute sulphuric acid.

Depolarising cells from the same period were usually based on nitric acid with a cell voltage of 1.9 Volts and included:

  • 1839 Grove cell, the first depolarising cell, it was a two electrolyte cell with nitric and sulphuric acid electrolytes and platinum and zinc electrodes
  • 1841 Bunsen cell, similar to Grove's cell, it replaced expensive platinum with cheaper carbon
  • 1853 Farmer cell, similar to Grove's cell with improved design of the porous pot.
  • 1854/5 Callan cell, the Maynooth battery, a two electrolyte cell. Expensive platinum or unreliable carbon cathodes were replaced by cast iron. The outer casing was cast iron, and the zinc anode was immersed in a porous pot in the centre.
  • Other variants on this theme were developed by Lansing B. Swan, Thomas C. Avery, Christian Schönbein, Archeneau, Hawkins, Niaudet, Tommasi and d'Arsonval.

Although these cells were popular, the acid decomposed rather than polarising the cell giving off toxic nitric dioxide gas which eventually led to their demise.

Other developments included:

  • The de la Rue silver chloride cell whose constant voltage and small size made it popular for medical and testing applications. The electrodes consisted of a small rod or pencil of zinc and a silver strip or wire coated with silver chloride and sheathed in parchment paper. The electrolyte was ammonium chloride contained in a closed glass phial or beaker to avoid evaporation.
  • The Schanschieff battery which used zinc and carbon electrodes and an electrolyte of mercury sulphate. It was suitable for portable applications such as reading and mining lamps.

All of the above cells were primary cells, but most were designed for re-use. In general, they used aqueous electrolytes enclosed in stout containers, often made of glass. Once the cell was discharged the spent chemicals could be replaced or replenished: - a form of mechanical recharging. High volume users such as the telegraph and telephone companies pioneered recycling, working with their battery suppliers to reprocess and recover expensive elements from the used electrolytes. (In 1886 Western Union recovered 3000 pounds of copper in this way.)

A further impetus was given to the search for alternative chemistries after 1860 when Gaston Planté demonstrated the feasibility of rechargeable cells with his Lead Acid battery.

All of the above primary cells were eventually superceded for PTT use by versions of Planté's rechargeable battery or by mains power.

For portable power, the Leclanché cell was one of the few surviving primary cells from this period.

1878 In a letter sent to the publication "Mechanic and World Science" Irish experimenter Denis D. Redmond described a 10 by 10 array of Selenium photocells each connected to a corresponding array of platinum wires which would glow when light impinged on the photocells. The system was the first to provide electric transmission of moving images, albeit silhouettes, only one year after the discovery of the photovoltaic effect and one year before Edison patented his light bulb. The system had no image scanning (later provided by Nipkow) so it required 100 channels to transmit the image. Nevertheless it was the forerunner of the modern television system.

The same year Portuguese professor Adriano de Paiva published "La téléscopie électrique basée sur l'emploi du sélénium" in a Portuguese publication "Commercio Portuguez", curiously written mostly in French with some Portuguese. It described a similar system to Redmond's which he called an electric telescope anticipating a different application from what eventually transpired.

It was another five years before practical photovoltaic cells were invented by Fritts.

1878 The world's first electric power station was built by Sigmund Schuckert at the instigation of King Ludwig II went into operation in the Bavarian town of Ettal. It contained 24 dynamo electric generators based on a design by Siemens driven by a steam engine. It was used to power an array of Siemens carbon arc lamps to illuminate the Venus Grotto in the gardens of Ludwig's Linderhof Palace.

1878 The bolometer, a very sensitive device for measuring very low levels of incident electromagnetic radiation, including infrared radiation, was invented by Samuel Pierpoint Langley. It works by measuring the heating effect of the radiation on the resistivity of a suitable conductive material. The name comes from the Greek bole ray of light, stroke, from ballein to throw.

Langley's bolometer used a Wheatstone Bridge with a sensitive galvanometer to measure the differential resistance between two Platinum strips coated with Carbon black, one exposed to the radiation and the other shielded from it. It was sensitive enough to detect the thermal radiation from a cow a quarter of a mile (400 m) away.

Modern bolometers use semiconductor or superconductor absorptive elements to pick up the radiation and are able to detect changes in temperature of less than 1/100,000 of a degree Celsius. They are commonly used to measure of the amount of solar energy reaching the Earth.

See also Langley's contribution to aviation.

See more about thermo-electricity.

1878 The invention which did more than any other to promote the use of electricity in the home, the incandescent electric light bulb, was patented in the UK by English physicist and chemist, Joseph Wilson Swan in 1878 and the following year in the USA by American, Thomas Alva Edison. (See following item).

Swan started his development of incandescent lamps in 1848 using platinum filaments but, because of the high cost of platinum and its short life before failing, he switched to carbon which could withstand the heat better. By 1860 he demonstrated a working device, and was granted a British patent covering a partial vacuum, carbon filament, incandescent lamp almost twenty years before Edison. Carbon unfortunately burns in the presence of oxygen and so must be enclosed in a vacuum and Swan's lamps still suffered from short lifetimes because of the difficulty of achieving a high enough vacuum. By 1878 however vacuum technology had advanced sufficiently and Swan was able to produce and patent a reliable carbon filament lamp.

1879 After an intensive search, starting in 1878, for suitable incandescent materials Thomas Alva Edison patented the Carbon filament, incandescent electric light bulb in the USA.

History is written by the winners and a certain mythology has built up around Edison's inventive genius. The light bulb itself is synonymous with bright ideas but also with Thomas Edison himself. Forgotten however is English experimenter Warren de la Rue's 1940 incandescent lamp using a platinum filament in a partially evacuated glass tube. Forgotten also are all the previous patents for electric lights similar to Edison's using carbon filaments in evacuated bulbs or bulbs filled with inert gas. These included American John W Starr from Cincinnati who was granted a UK patent in 1845 for a carbon filament incandescent lamp which he successfully demonstrated to Michael Faraday. Unfortunately Starr was found dead in bed the day after the demonstration at the age of 25, it is said, of "excitement and overwork of the brain" and nothing further became of his invention. Forgotten too are the similar inventions of Alexander Lodygin in Russia (1872), Henry Woodward and Matthew Evans in Canada (1874) and Joseph Swan in the England (See previous item) who demonstrated an almost identical lamp to the Newcastle Literary and Philosophical Society eight months before Edison's "breakthrough". Edison actually sued Swan for patent infringement and the matter was finally settled out of court when the rivals formed the Edison and Swan United Electric Company.

Although Swan got there first, at the time, the only source of domestic electrical energy generally available was the battery and so all the lighting development took place using DC/battery power and it was Edison who popularised the invention by providing the necessary electricity generating and distribution systems to power the lamps which made electric lighting practical.

Considering that Edison's name is almost synonymous with the invention of the light bulb it is perhaps surprising to note that in 1883 the US Patent Office ruled that a prior invention patented in 1878 by William Sawyer and Albon Man took precedence.

See also Tesla (1887)

Despite the unfortunate ending in 1874 of Edison's relationship with William Orton the head of Western Union, in 1877 Edison was hired once more by Orton to try to break Bell's patents on the telephone. Orton is quoted as saying that "Edison had a vacuum where his conscience ought to be". The battlefield was to be the telephone transmitter where Bell's design was inadequate but several others were already working on this. Edison provided an innovative design but it also used ideas developed by others and Edison's rights to these were only settled after litigation. He was paid over $100,000 for his solution by Western Union and this gave him the funding and the independence he needed to develop his creative talent. (Bell's lawyers later successfully overturned Orton's main patent challenges to Bell's system although Edison's patents on the carbon microphone were upheld.)

Edison, became known as the Wizard of Menlo Park, where he employed an army of engineers working on development projects and an aggressive team of lawyers. He made his first patent application in 1868 when he was 21 years old and over his lifetime he was granted 1,093 U.S. patents including 106 in 1882. In addition he also filed an estimated 500-600 unsuccessful or abandoned applications. This amounts to two successful patents per week during his most productive period and a patent application on average every eight working days over his long working lifetime of sixty years. Considering that three of these inventions, the light bulb, the phonograph and the movie projector for which he is famous each took several years of development, and at the same time he had a large company to run, you have ask your self how much Edison himself contributed to the patents which bear his name.

Canadian author Peter McArthur is quoted as saying in 1901 "Every successful enterprise requires three men: a dreamer, a businessman and a son-of-a-bitch". The giants of the industry seem to embody all three of these characteristics at the same time.

The tale of the light bulb is a re-run of the disputes and dirty dealings around the invention of telegraphy by Morse and Edison, Bell's telephony,  Edison's carbon microphone and Bain's electric clock and Fax machine, stories and intrigues destined to be repeated with AC electrical power generation and distribution,  radio (Marconi),  radio and telephony (Pupin) and computers, and each new technology advance, though surprisingly the "invention" of the internet seems relatively free from such disputes and charlatans.

1879 Repeating the 1858 experiment of Plücker and Hittorf Sir William Crookes used a Geissler vacuum tube with an anode in the shape of a cross noticed that the cross cast a shadow on a zinc sulfide fluorescent coating on the end of the tube. He hypothesized that there must have been rays coming from the cathode which caused the zinc sulfide to fluoresce and the cross to create a shadow. He called these rays cathode rays. Crookes tubes were used by Röntgen in 1895 to demonstrate X-rays and by J. J. Thomson in 1897 in his discovery of the electron.

Crookes also invented the radiometer which detects the presence of radiation. It consists of an evacuated glass bulb in which lightweight metal vanes are mounted on a low friction spindle. Each vane is polished on one side, and blackened on the other. In sunlight , or exposed to a source of infrared radiation (even the heat of a hand nearby can be enough), the vanes turn with no apparent motive power.

Crookes was a believer in the occult and in the 1870's claimed to have verified the authenticity of psychic phenomena. He was knighted by Queen Victoria who, it is rumoured, had similar interests.

1879 American physicist Edwin Herbert Hall discovers that when a solid material carrying an electric current is placed in a magnetic field perpendicular to the current, a transverse electric field is created in the current carrier. Known as the Hall Effect in his honour. The voltage drop across the conductor at right angles to the current is called the Hall Voltage and is proportional to the external magnetic field. Now used in sensors for measuring magnetic field strength.

1879 Siemens Halske demonstrate an electric railway at an exhibition in Berlin. Power was provided from a separate generator which supplied the train via a third rail. A similar system was built in 1883 to run a commercial service along Brighton promenade in the UK by the son of a German clockmaker, Magnus Volk, an electrical engineer who had already completed the electric lighting of Brighton Pavilion. It was the world's first publicly operated electric railway when it opened and with some modifications his trains are still carrying passengers along the promenade today.

1879 Austrian physicist Josef Stefan formulated a law which states that the radiant energy of a blackbody is proportional to the fourth power of its temperature.

1879 After five years working as music professor, Welsh born American David Edward Hughes resigned in 1855 to patent a printing telegraph which became very successful in the USA and most of Europe, except Great Britain, bringing him international honours. In 1879 he invented the induction balance, the basis of the metal detector. It consists of two coils, one transmitting a low frequency signal and one connected to a receiver (detector) arranged in such a way that the receiver coil is close to, but shielded from, the transmitter coil so that in free space it does not pick up (detect) any signals from the transmitter. When the coils are brought near to a metal object, small perturbations in the magnetic field upset the balance between the coils causing a current to flow in the receiving coil thus indicating the presence of the metallic object.

The same year while working on his induction balance he noticed a clicking in a separate home made telephone ear-piece which was not connected in any way to the induction balance. He diagnosed this to be caused by a loose wire in his induction balance since the clicking stopped when the wire was firmly connected. He deduced that invisible waves, which he called aerial transmissions and which would today be called radio waves, were being emitted from a spark gap which occurred when the wire in the transmitting coil of the induction balance became disconnected and that the ear piece was picking them up. Investigating further he devised a clockwork device for opening and closing the spark gap and was able to pick up signals from the spark gap with his telephone receiver over ever greater distances, up to 500 yards, walking up and down Great Portland Street in London. Effectively he made the world's first mobile phone call. In 1880 Hughes demonstrated the phenomenon of radio communications to the Royal Society in London but the president, mathematician William Spottiswoode was not impressed. According to George Gabriel Stokes, Irish mathematician and physicist specialising in hydraulics and optics, who witnessed the demonstration, the phenomenon was explained by induction not radio waves. Discouraged, Hughes passed on to other interests and did not pursue his discovery. Eight years later Hertz was credited with the discovery of radio waves.

1880 The brothers Pierre Curie and Jacques Curie predicted and demonstrated piezoelectricity.

1880 Emile Alphonse Fauré in France patented pasted plates for manufacturing lead-acid batteries. The lead plates were coated with a paste of lead dioxide and sulphuric acid which greatly increased the capacity of the cells and reduced the formation time. This was a significant breakthrough which led directly to the industrial manufacture of lead-acid batteries.

1880 Herman Hammesfahr, a German immigrant to the USA, was awarded a patent for a durable and flame retardant fibreglass cloth with the diameter and texture of silk fibres. He showed a glass dress at the 1893 Chicago World Fair. (Also attributed to American glass manufacturer Edward Drummond Libbey founder of Owens-Illinois).

1881 Improvements to the Leclanché cell, to avoid leakage, by encapsulating both the negative electrode and porous pot into a sealed zinc cup were patented by J.A. Thiebaut.

1881 The first electric torch or flashlight patented by English inventors Ebenezer Burr and William Thomas Scott. The original lamps were designed as portable table lamps and powered by a wet cell battery in a waterproof box. At the time the first power station had not yet been commissioned and there were no households wired up for mains electricity. More convenient portable versions of the torch using the recently invented dry cells were introduced starting in 1883. They quickly became popular for bicycle and miners lamps.

1881 Lead acid rechargeable batteries were first used to power an electric car by M. G. Touvé in France.

1881 The first International Electric Congress or International Conference of Electricians convened in Paris to define the international terms for the electrical units of electromotive force (Volt), resistance (Ohm), current (Ampère) The Congress also specified the manner and conditions in which the units were to be measured. Up to this time there had been at least twelve different units of electromotive force, ten different units of current, and fifteen different units of resistance.

The standard Ohm was defined by the resistance of a specified column of mercury, the standard Ampère by the current which deposits metallic silver at a specified rate from a silver nitrate solution and the standard Volt was defined by the EMF produced by an electrical circuit passing through an electrical field at a specified rate. However since most laboratories were not equipped to generate a standard Volt in the specified manner, and in any case they used batteries to provide their source of electric potential, a new voltage standard was devised, based on the EMF produced by a standard Clark cell and this was adopted at the fourth International Electric Congress in Chicago in 1893. Unfortunately with the three standards each based on independent measured quantities, Volts did not always equal Amps multiplied by Ohms and the voltage standard had to be changed once more. The 1908 International Congress in London consequently changed the Volt to a derived unit based on the standard Ampère and standard Ohm.

1881 American engineer Frederick Winslow Taylor working at the Midvale Steel company introduced Time and Motion Studies or Work Study and Method Studies to streamline manufacturing and eliminate unnecessary work. They enabled major efficiency savings to be made and became the foundation of Scientific Management.

1881 Patent granted to William Wiley Smith for the induction telegraph used to communicate with moving trains. Soon afterwards improved versions were invented independently by Lucius J. Phelps (1884), Edison (1885) and black American Granville T, Woods (1887). The system consisted of a track-side wire or rail which could pick up signals from an induction coil mounted on the train, essentially acting as the primary and secondary windings of a transformer. The forerunner of the mobile phone.

Similar systems, based on the same principle, were also used for fixed wireless communications before the discovery of radio (Hertzian) waves.

1882 French physicist and physician Jacques Arsène d'Arsonval invented the moving coil galvanometer. It had shaped pole pieces which enabled it to have a linear scale and became the basis of all modern electromechanical analogue panel meters.

1882 Nikola Tesla, working in Budapest, identified the rotating magnetic field principle and the following year used it to design a two-phase induction motor.

1882 French chemists Felix de Lalande and Georges Chaperon introduce the first battery to use alkaline electrolyte, the Lalande-Chaperon cell, the predecessor of the Nickel-Cadmium cell. Using electrodes of Zinc and Copper Oxide with a Potassium Hydroxide electrolyte, it was rechargeable and produced a voltage of 0.85 Volts.

Up to that point, all batteries had used acidic electrolytes. They chose to investigate alkaline rather than acidic electrolytes because electrodes of most metals and their compounds are attacked by the acid. Lead is one of the few metals resisting the acids but it is very heavy and a weight savings would be secured by using almost any other metal.

1882 English amateur scientist James Wimshurst invented the Wimshurst Electrostatic Generator, the first machine capable of generating high voltage static electricity that was unaffected by atmospheric humidity. Static electrical charges of opposite polarity built up on its two fourteen and a half inch (38 cm) contra-rotating discs sufficient to draw a four and a half inch (12 cm) spark. Since the breakdown voltage for air is 30,000 Volts per centimetre, this small table top machine was capable of generating over 300,000 Volts. As a reliable source of high voltage electricity, it not only provided a practical power source for X-ray machines, but it was a boon to Victorian experimenters enabling them to carry out serious scientific investigations or to carry out dubious experiments in electrotherapy. Wimshurst's basic design is still used in electrical laboratories today.

James Wimshurst was the son of British ship builder Henry Wimshurst who built the Archimedes, the world's first propeller driven steamship, using the screw propeller patented in 1836 by John Ericsson. The Archimedes was used to lay the first successful Atlantic cable in 1866, replacing the ill fated 1858 original cable.

1882 Ayrton and Perry in England build an electric tricycle with a range of 10 to 25 miles powered by a lead acid battery and sporting electric lights for the first time. (Four years before the first Internal Combustion Engine car by Karl Benz)

1882 British engineer, James Atkinson patented modifications to the spark ignition, four stroke, internal combustion engine to circumvent Otto's patent. The design used a complex crankshaft arrangement to provide a longer exhaust (power) stroke than the induction stroke to improve the efficiency of heat cycle. The penalty was a more complicated mechanical mechanism as well as a larger, heavier engine. The industry however preferred the simpler Otto design and Atkinson's design did not achieve commercial success in his lifetime. Recently however the design is making a comeback as fuel efficiency becomes a priority.

See also Heat engines.

1882 In a display of optimism the first small domestic electrical appliances begin to appear, three months before power was available from the first electricity generating station. The electric fan, a two bladed desk fan was invented by Schuyler Skaats Wheeler manufactured by Crocker and Curtis electric motor company and the electric safety iron was invented by New Yorker Henry W. Seely.

1882 The world's first large scale central electricity generating plants or power stations were completed by the Edison Electric Lighting Company. (The first practical power plant commission by Schuckert in 1878) The first to come on stream in April was Holborn Viaduct in London powering 2000 electric lamps. The second, in September, was on on Pearl Street in New York City's financial district, supplying 85 customers. Reciprocating Porter and Allen steam engines provided the motive power (about 900 horsepower) to 27 ton direct-current (DC) dynamos which produced 100 Kilowatts of power at 110 Volts. The overall energy efficiency is estimated at 6%.

1882 Young American engineer William Joseph Hammer testing light bulbs for Edison noted a faint blue glow around the one side of the filament in an evacuated bulb and a blackening of the wire and the bulb at the other side, a phenomenon which was first called Hammer's Phantom Shadow. In an attempt to keep the inside of the electric lamps free of soot he placed a metal plate inside the evacuated bulb and connected a wire to it. He noted the unidirectional or "one-way" current flow from the incandescent filament across the vacuum to the metal plate but he was unable to explain it or realise its significance at the time. It was in fact due to the thermionic emission of electrons (not discovered until 1897 by J.J Thomson) from the hot electrode of the filament, flowing to the cold electrode of the plate creating in effect a vacuum diode or valve. In 1884 Edison was awarded a patent for a device using this effect to monitor variations in the output from electrical generators. The indicator proved ineffective however Hammer's discovery of thermionics was henceforth known as the Edison effect. The Edison effect is the basis of all the vacuum tube devices and thus the foundation of the electronics industry in the early 20th century. The first practical vacuum tube diode was patented by Fleming in 1904.

1882 English engineer John Hopkinson patented the three-wire, three phase system for electricity generation and distribution. This system saved over 50 percent of the copper in the conductor.

1883 Hopkinson demonstrated the principle the synchronous motor.

Hopkinson died at the age of 49 in a mountaineering accident in Switzerland, together with one of his sons and two of his three daughters.

1883 Edison patents the fuse.

1883 Charles Edgar Fritts an American inventor built the first practical PhotoVoltaic module by coating selenium wafers with an ultra thin, almost transparent layer of gold. The energy conversion efficiency of these early devices was less than 1%. Denounced as a fraud in the USA for "generating power without consuming matter, thus violating the laws of physics" the idea of solar cells was taken up and commercialised by Siemens in Germany.

1883 Irish physicist George Francis FitzGerald suggests that Maxwell's theory of electromagnetic waves indicates that radio waves can be produced by an oscillating electric current.

1884 In an attempt to simplify Maxwell's Equations British engineer, physicist and mathematician Oliver Heaviside developed the branch of mathematics known as vector calculus. Maxwell expressed his theory with a cumbersome series of 20 partial differential equations with 20 variables representing the electric and magnetic fields. The equations for the fields were dependent on the coordinate system used. In each of cartesian, polar or spherical coordinate systems, three different equations were needed to represent the three possible components of the field directions. Heaviside defined the new vector operators, GRAD, DIV and CURL which enabled him to rewrite Maxwell's equations in vector notation, in a form which is independent of the coordinate system, with only four equations with four variables. Maxwell's equations are now, normally presented in the form developed by Heaviside.

Heaviside contributed much to communications theory but sadly remained unrecognised in his lifetime. In 1880 he patented the coaxial cable. In 1887 he investigated the causes of distortion in transmission lines showing mathematically that it was due to the distributed capacitance along the line, and more importantly, that it could be corrected or reduced by adding distributed inductance along the line. His suggestion to install induction coils at intervals along transmission lines was turned down by William Preece the assistant chief of the British Post Office who controlled the lines and it was published without fanfare in "The Electrician". The idea however was taken up in America by AT&T and by Michael Pupin a Columbia University lecturer in mathematical physics. Pupin subsequently patented the idea of inductive loading coils in 1899 and "Pupin coils" were implemented by AT&T throughout their network enabling them to increase dramatically the range of their telegraph and telephone cables. The patent made him extremely wealthy, much to Heaviside's chagrin, not so much for the money, which was never important to him, but for the recognition which he felt he deserved. While initially acknowledging Heaviside's contribution, Pupin changed his stance when the value of his patent became clear. His autobiography, "From Immigrant to Inventor", an example of the American dream, won him a Pulitzer Prize. In it, he rubs salt into Heaviside's wounds by mockingly crediting inspiration for "his invention" to a herdsman from his native Serbia who showed him how to send sound signals by tapping on the ground.

Heaviside is remembered today more for his 1902 prediction, published in the Encyclopaedia Brittanica, of the ionised layer in the upper atmosphere which reflected radio waves making long distance radio transmission possible by bending the radio wave around the curvature of the Earth. Known as the Heavisde Layer, or the Kennelly-Heaviside Layer since Arthur Edwin Kennelly an expatriate Briton working in the USA also independently made the same prediction at the same time, its existence was verified in 1924 by Edward Victor Appleton.

Heaviside's life was not a happy one. He was not a wealthy man and worked much of his life with no regular income. His mathematics were difficult to understand even by the most technically literate and the injustice of Pupin's exploitation of his ideas affected him greatly. An embittered man, he never married, living an eccentric existence in bare rooms furnished with granite blocks. In later life his appearance became more and more unkempt and children would taunt him in the street, shouting "Poop. Poop. Pupin".

1884 Charles Renard uses a Zinc/Chlorine Flow Battery to power his air ship La France with the chlorine being supplied by an on board chemical reactor containing Chromium Trioxide and Hydrochloric Acid.

1884 Swedish chemist Svante August Arrhenius working at the University of Uppsala published his PhD thesis on the Galvanic Conductivity of Electrolytes explaining the process by which some compounds conduct electricity when in solution. He proposed that when a compound like table salt NaCl (sodium chloride) was dissolved in water, it dissociated into positively and negatively charged "ions" (Greek for "the ones that move" or "wanderers") Na+ and Cl- whose motions constituted a current. These ions drift freely through the solution but when positive and negative electrodes are introduced into the electrolyte, as in electrolysis, the ions drift towards the electrode of opposite polarity. He defined acids as any substance, which when dissolved in water, tends to increase the amount of H+ hydrogen ions and bases as any substance, which when dissolved in water, tends to increase the amount of OH- hydroxide ions. (These definitions do not cover all possibilities which are now known to exist).

His 1884 thesis was treated with disbelief and was given the lowest passing grade at the time, however he was vindicated with the discovery of the electron by J J Thomson in 1897 and his disparaged thesis won him the Nobel Prize for chemistry in 1903.

In 1887 Arrhenius was the first to develop the theory quantifying the rate at which chemical reactions proceed, now known as Arrhenius Law.

In 1896 Arrhenius was also the first to describe the "Greenhouse Effect" and its causes.

1884 French chemist Henri Louis Le Chatelier discovered the chemical equivalent of Lenz Law of electromagnetism. It was published in simpler form 4 years later as: "If the conditions of a system, initially at equilibrium, are changed, the equilibrium will shift in such a direction as to tend to restore the original conditions". The conditions refer to concentration, temperature and pressure. Le Chatelier's Principle allows you to predict which way the equilibrium will move when you change the reaction conditions, and helps provide ways to increase the yield in a chemical reaction.

1884 German engineering student Paul Gottlieb Nipkow patents an electromechanical image scanning system the basis for television raster scanning. The system was made possible by use of the photoconductive properties of the element selenium recently discovered by Fritts. Previous attempts at transmitting images such as Redmond's had used one channel, or pair of wires, to transmit each picture element. Nipkow's design needed only one pair of wires for transmitting the image. He used a rotating disk with holes, through which the scene could be observed, arranged circumferentially around the disc in a spiral between the centre and the edge. Light passing through the holes as the disk rotated, impinged on a selenium photocell, generating an electrical signal proportional to the brightness of the scene which could be transmitted down wires to a receiver. As the disk rotated it produced a rectangular scanning pattern or raster which scanned the scene. The number of scanned lines was equal to the number of holes and each rotation of the disk produced a television frame. A similar Nipkow disc, synchronised with the transmitter disc, was used in the receiver and the received electrical signal was used to to vary the brightness of a light source illuminating a projection screen. The light passing through the rotating disk formed a raster on the projection screen allowing an image to be built up. Like all television systems, it depended on the principle of "persistence of vision" and rapid scanning was needed to ensure that it worked. This was the first example of transmitting moving images electrically down a wire however it is not clear whether Nipkow actually built a working system. The signals from the selenium were very low and needed amplification for a practical system and it was not until 1907 that De Forest's audion made this possible.

1885 German physicist Eugen Goldstein using a cathode ray tube with a perforated cathode discovered rays of positively charged particles emerging from holes on the sides of the cathode and moving in the opposite direction of cathode rays. He called these rays Canal rays. The particles were later determined by Wien to be protons with a mass almost 2000 times the mass of an electron.

1885 Italian physicist Galileo Ferraris discovered the rotating magnetic field that he applied to the first 4 pole induction motor. He did not patent his invention but offered it freely to "the service of mankind"

1885 Russian Nikolai Benardos and Polish Stanislav Olszewski were granted a patent for an electric arc welder with a carbon electrode. They are considered the inventors of modern welding apparatus although electric arc welding was first proposed by Lindsay fifty years earlier in 1835.

1885 Engineers from the Ganz factory in Hungary, Ottó Titusz Bláthy, Miksa Déri and Károly Zipernowsky demonstrated at the National Exhibition in Budapest, a high voltage alternating current distribution system using toroidal transformers which they also designed. The entire exhibition was illuminated by 1,067 X 100 Volt incandescent lamps supplied by 75 transformers taking their power from a 1,350 Volt 70 Hz distribution system.

In modern day power transformers the windings are usually wound around a laminated iron (Silicon steel) core (either directly or on a former). The Ganz transformers at the time provided a breakthrough in efficiency because of their unique construction which improved the transformer's magnetic circuit. The primary and secondary windings were first wound together in the shape of an annular ring and this formed the core of a torus. The magnetic circuit was made by toroidally winding thousands of turns of iron wire around the copper windings, completely encasing them in magnetic material which almost filled the inner space of the ring.

Bláthy also patented the first alternating-current kilowatt-hour meter in 1889.

1885 German mechanical engineer, Karl Friedrich Benz designed and built the world's first practical automobile to be powered by an internal combustion engine. It was a "three wheeler", powered by a water cooled 958cc, 0.75hp four stroke engine based on Nicolaus Otto's patent with electric ignition and differential gears. He was granted a patent for the gasoline fuelled "motor carriage" the following year and built his first four wheeled car in 1891. His invention marked the start of the slow demise of the battery driven car.

1885 British engineer Charles Algernon Parsons had produced his first steam turbine in 1885 but had failed to generate any commercial interest in it. One of his key innovations was the compound turbine which used a set of stator blades to redirect the steam after it had passed through the first rotor blades so that it could be directed through a second rotor and hence to further rotor/stator pairs. This allowed much higher power outputs and efficiencies to be achieved.

To publicise his invention, in 1894 he took out a patent on the turbine and commissioned a 100 foot long steel boat, the Turbinia, to demonstrate its capability. Initially he did not achieve the desired speed through the water as its propellers, rotating at 18,000 rpm, suffered from the previously unheard of problem of cavitation and churned up the water as bubbles formed behind the blades due to sudden pressure reduction. However by slowing down the turbine and modifying the propellers he was able to achieve a speed of 34.5 knots. Still his target customer the Admiralty were unimpressed. According to Parson's biographer Ken Smith, Parsons dictum was "If you believe in a principle, never damage it with a poor impression. You must go all the way". His opportunity came at the 1897 Spithead Naval Review of 160 of the navy's ships, arranged to show off the might of the Royal Navy to Queen Victoria and invited foreign dignitaries on the sixtieth anniversary of the queen's accession to the throne. The navy's best boats were capable of no more than 30 knots and the Turbinia astonished the gathered crowd by steaming up and down the navy's lines leaving their fastest boats in her wake. The steam turbine's future was assured. Today 86% of the world's electricity is generated using steam turbines.

See more about Steam Turbines and how they work.

See more about Steam Engines


1886 After Bláthy's demonstrations of alternating current power distribution the previous year, New Yorker, William Stanley Jr in the USA patented the "Induction Coil", invented by Michael Faraday in 1831, what we would now call a transformer. This opened the door to the widespread use of AC power for domestic applications. Battery power, once the only source of electricity in the home, now had a serious competitor.

1886 Carl Gassner of Mainz patented the carbon-zinc dry cell which made batteries the convenient power source they are today. It used the basic Leclanché (1868) cell chemistry with zinc as its primary ingredient with the chemicals being encased in a sealed zinc container which acted as the negative electrode. A carbon rod immersed in a manganese dioxide/carbon black mixture served as the positive electrode. Initially the electrolyte was ammonium chloride soaked into the separator which was made of paper, but by adding zinc chloride to the electrolyte the wasteful corrosion of zinc when the cell was idle was reduced - adding considerably to the shelf life. A bitumen seal prevented leakage. Although the technology has been refined by over a century of development, the concepts and chemistry are the same as Gassner's first cells.

Previously most wet primary cells could be recharged mechanically by replacing the spent chemicals. The used electrolyte could then be recycled to recover the the basic constituents. The advent of the dry cell marked the beginning of the single use, throwaway, primary cell since it was no longer easy or possible for the user to replace or replenish the active chemicals.

1886 Patent granted to American chemist Charles Martin Hall for the electrolytic process for extracting aluminium from its bauxite ore, aluminium oxide or alumina. His discovery was made in a laboratory he set up at home, using home made Bunsen batteries, shortly after finishing his undergraduate studies. The process was discovered simultaneously by French chemist Paul Héroult and is now called the Hall-Héroult process.

Aluminium is the most abundant metal and the third most abundant element in the earth's crust but, because it is highly chemically reactive, it does not occur in nature as a free metal. Before Hall discovered a practical way of extracting it from its ore, aluminium metal was extremely rare and cost more than gold.

On an industrial scale the process uses enormous amounts of electricity, consequently aluminium extraction plants are normally located close to the sources of cheap hydroelectric power.

Hall went on to found ALCOA, the Aluminium Company of America.

See also Héroult

1886 English inventor Herbert Akroyd Stuart built the first compression ignition engine which he patented in 1890. In subsequent patent disputes with Rudolf Diesel who patented a similar engine in 1893, Akroyd Smith's claim to priority was upheld.

1887 Kelvin patented the electrostatic voltmeter.

1887 Arrhenius publishes the equation named after him showing the exponential relationship between the rate at which a chemical action proceeds and its temperature, the rate doubling with each 10°C rise in temperature.

1887 American inventor Elihu Thomson patents the electric welding (resistance welding) process. The technique used for making battery interconnections.

1887 By 1887 huge strides had been made in the electrical power industry since the invention of the first practical dynamo 20 years earlier.

1887 - 1890 Croatian-born physicist Nikola Tesla filed for numerous US patents on AC distribution systems and polyphase induction motors and generators based on the rotating field principle he discovered in 1882. This enabled inexpensive and unlimited electric power to be brought to the home consumer thus sealing the fate of the DC system and the use of DC in domestic applications.

Contracted for $50,000 by Thomas Edison (a supporter of DC transmission) to improve his DC dynamos Tesla worked night and day to deliver the solutions on time a year later to Edison but Edison refused to pay saying he had been a joking about the contract. Tesla resigned in disgust and went to work for George Westinghouse promoter of AC distribution and Edison's arch rival. Edison with some success, spent the rest of his life trying to undermine Tesla.

For two years after Tesla left, Edison staged a morbid public relations campaign in the notorious current wars to demonstrate that the Westinghouse AC distribution system was dangerous by promoting the AC powered electric chair for carrying out the death penalty and calling such executions "Westinghousing". At the same time he arranged public executions of farm animals which he attended personally in the courtyard of his laboratory using AC power, starting with dogs and escalating to calves then horses.

Edison's system itself was responsible for a number of deaths due to mechanical failure or ignorance as the deceptively similar high voltage wires were installed overhead near to the more familiar low voltage telegraph wires.

In 1915 Reuters and the New york Times carried reports that Tesla and Edison were to share the Nobel Prize for physics. Mystery surrounds what happened next, but no such prize was awarded and it is claimed that Edison, whose fame and wealth were secure, turned down the award to deprive Tesla of a much needed $20,000. Others claim Tesla himself turned it down not wanting to be associated with Edison whom he called "a mere inventor". The Nobel Foundation did not deny that Tesla and Edison had been their first choices.

Despite having over 800 patents Tesla died penniless.

1887 British engineer, born in Liverpool, with the distinctly un-British name of Sebastian Pietro Innocenzo Adhemar Ziani de Ferranti, (his father was a photographer and his grandfather, Guitarist to the King of Belgians), designed the generation and distribution systems for Deptford Power Station (1887-1890), which at that time was the largest in the world. Power was supplied by four single phase 1000 kW, 10,000 Volts, 85 cycle/sec alternators. Ferranti pioneered the use of Alternating Current for the distribution of electrical power in Europe authoring 176 patents on the alternator, high-tension cables, insulation, circuit breakers, transformers and turbines.

Ferranti also designed the first flexible high voltage cables for power distribution using wax-impregnated paper for insulation, a technique which was used exclusively until synthetic materials became available.

In the same year Ferranti also patented the induction furnace in which materials are heated by eddy currents induced within the material itself, generated by placing the material in the magnetic field of an induction coil.

1887 British physiologist Augustus Waller of St. Mary's Medical School in London published the first human electrocardiogram - recorded by lab technician Thomas Goswell.

1887 Fibreglass invented again by Charles Vernon Boys a physics demonstrator at the London's Royal College of Science who produced glass fibre strands by using the end of an arrow fired from a miniature crossbow to draw strands of molten glass from a heated vessel.

1887 German physicist Heinrich Rudolf Hertz discovered the photoelectric effect, that physical materials emit charged particles (electrons) when they absorb radiant energy. During electromagnetic wave experiments he noticed that a spark would jump more readily between two electrically charged spheres when there surfaces were illuminated by the light from the other spark. Light shining on their surfaces seemed to facilitate the escape of electrons.

The photoelectric effect was not explained until 1905 by Albert Einstein who used quantum theory proposed in 1900 by MaxPlanck.

1888 Heinrich Hertz is generally considered to be the first to transmit and receive radio waves. (But see also Hughes 1880). Hertz demonstrated the existence of electromagnetic waves, predicted by Maxwell in 1864 and justified theoretically by him in 1873, by transmitting an electrical disturbance between two unconnected spark gaps situated 1.5 metres apart. He set up a wire loop containing spark gap (the transmitter) through which a large spark was deliberately generated. This caused a small spark to jump across another spark gap (the detector) at the ends of a similar wire loop situated near to but not connected to the transmitting loop. The wire loops were effectively the world's first radio transmitting and receiving antennas.

He showed that radio waves travel in straight lines and can be reflected by a metal sheet.

Hertz died of a brain tumour at the age of 36 without ever seeing the practical applications which resulted from his discoveries. The unit of frequency is named the Hertz in his honour.

Like Hughes who discovered the phenomenon before him, Hertz failed to see the potential of radio for communications. Hertz told one of his pupils " I don't see any useful purpose for this mysterious, invisible electromagnetic energy".

Hertz' (or should we say "Maxwell's") radio waves now form the basis of all broadcast radio and television, radar, satellite navigation, mobile phones and much of the backbone of the world's communications systems. Maxwell provided the theoretical basis for the technology, Hertz showed it was possible but there were many, many worthy contributors whose inventions were needed to make it happen. Each country had its national champions who invented transmitters, receivers, antennas, tuners, detectors, filters, oscillators, amplifiers, transducers, displays, batteries and other components and a variety of coding, modulation, multiplexing, compression, encryption schemes, communications protocols and software. There were however five players associated with the fundamental developments in radio technology whose contrasting fortunes are worth mentioning briefly here namely: Marconi, Fessenden, Armstrong, Watson-Watt and Dippy.

See more about Electromagnetic Radiation and Radio Waves today.

1888 German physicist Wilhelm Ludwig Franz Hallwachs discovers another example of photoelectric emission. (Becquerel's was the first). Following up Hertz' experiments on how light affected the intensity of spark discharges, he noticed that the charge on an insulated, negatively charged plate leaked away slowly but when it was illuminated with ultraviolet light the charge leaked away very quickly. On the other hand a positively charged plate was unaffected by the light. This phenomenon, now known as the Hallwachs effect, was later explained to be due to the emission of electrons from certain metallic substances when exposed to light. It is the basis of the modern photocell. Note that this is different from the photovoltaic effect in solar cells.

1888 Spanish naval officer Isaac Peral built the first electrically powered submarine.

Later the same year the French launched Gymnôte, a 60 foot submarine designed by Gustave Zede. It was driven by a 55 horse power electric motor, originally powered by 564 Lalande Chaperon alkaline cells by Coumelin, Desmazures et Baillache with a total capacity of 400 Amphours weighing 11 tons and delivering a maximum current of 166 Amps. These batteries were replaced in 1891 by 204 Laurent-Cely Lead acid cells, which were in turn replaced in 1897. Although the batteries were rechargeable, they could not be charged at sea.

An electric submarine was also built by Polish inventor Stefan Drzewiecki for the Russian Tzar in 1884.

1888 Austrian botanist Friedrich Reinitzer investigating the behaviour of cholesterol in plants observed cholesteryl benzoate changing into its liquid crystal state, nine years before the invention of the CRT. For nearly a hundred years afterwards liquid crystals remained little more than a chemical curiosity. See Dreyer (1950) and Heilmeyer(1968)

1888 An irate Kansas City undertaker Almon B. Strowger patented the automatic telephone exchange.

When Alexander Bell first started selling telephones, he sold them in pairs because the few subscribers that there were at the time could connect to eachother directly. As the number of telephones grew, the need quickly arose to be able to connect to more than one subscriber, but running telephone lines from each subscriber to every other subscriber was impractical so the telephone exchange with a manual switchboard was born. Each subscriber was connected to a switchboard at the exchange. When a subscriber wanted to make a call he would call the exchange and the telephone operator would connect his line to the called party line via a cable on the switchboard to complete the circuit. Strowger was infuriated by this system, since there was another undertaker in town who happened to be friends with the telephone operator and whenever someone called the operator asking to be put through to an undertaker, all the calls went to his competitor. He therefore set about designing an automatic exchange that would eliminate the need for operators.

In Strowger's design the telephone dial sent a series of pulses corresponding to each digit of the telephone number. At the telephone exchange the dial pulses would step a 10 position, rotary selector switch, called a uniselector, to a telephone line corresponding to the digit. For multi-digit telephone numbers, each line of the uniselector corresponding to the first digit was connected to a second uniselector, so that 100 lines could be accessed with 11 uniselectors. By adding a third stage, with 100 more uniselectors, 1000 subscribers could be accessed. In practice the uniselectors were designed as two-motion selectors with two dialling stages in one bank making 100 possible connections. The first stage was a rotary movement and the second stage was a linear movement with the selector stage moving up and down to connect to a set of contacts arranged vertically. This system formed the backbone of telephone communications in many countries of the world for almost 100 years.

Interestingly, before the familiar rotary telephone dial was invented, Strowger's first telephone sets used push button dialling, which required the caller to provide the pulses by tapping on the keys.

1888 AT&T engineer, Hammond V. Hayes developed the common battery system which permitted a central battery to supply all telephones on an exchange with power, rather than relying upon each subscriber's own troublesome power supply. It allowed all telephone signalling and speech to be powered from single large central 24 Volt lead acid batteries mounted in central telephone exchanges, eliminating the need for magnetos and Leclanché cells to be installed in every subscriber's premises. The system is still in use today.

1889 Elihu Thomson invents the motor driven recording wattmeter.

1889 Russian engineer Michail Osipovich Dolivo von Dobrovolski working for AEG in Germany made the first squirrel cage induction motor.

1889 Walther Hermann Nernst a German physical chemist applied the principles of thermodynamics to the chemical reactions proceeding in a battery. He formulated an equation (now called the Nernst Equation) for calculating the cell voltage taking into account the electrode potentials, the temperature and the concentrations of the active chemicals. It applies to the equilibrium position i.e. no current. This is a special case of the more general Gibbs free energy relationship and is one of the basic formulas used by cell designers to characterise the performance of the cell.

He also showed that in a reversible system the electrical work done is equal to the change in free energy. Also known as the enthalpy.

Nernst stated the Third Law of Thermodynamics that it is impossible to cool a body to absolute zero, when it would have zero entropy, by any finite process. In a closed system undergoing change, entropy is a measure of the amount of energy unavailable for useful work. At absolute zero, when all molecular motion ceases and order is assumed to be complete, entropy is zero.

1889 America's first alternating current (AC) hydroelectric power generating station was put into service at Willamette Falls, Oregon. Using Westinghouse generators it was also America's first AC transmission system providing single phase power at 4000 Volts which was transmitted to Portland 14 miles away where it was stepped down to 50 Volts for distribution and used to power the street lights.

1890 Dundee born engineer James Alfred Ewing discovers the phenomenon of hysteresis which he named after the Greek "hysteros" meaning "later". He observed that, when a permeable material like soft iron is magnetised by being subjected to an external magnetic field, the induced magnetisation tends to lag behind the magnetising force. If a field is applied to an initially unmagnetised sample and is then removed, the sample retains a residual magnetisation becoming a permanent magnet. He speculated that individual molecules act as magnets, resisting changes in magnetising potential and described the characteristic curve of the magnetic induction B versus the magnetic field H which caused it, calling it a hysteresis loop See diagram. Also known as the BH loop, it was later shown by Steinmetz that the area of the hysteresis loop is proportional to the energy expended in taking the system through a complete magnetisation - demagnetisation cycle. This wasted energy appears as heat and represents a considerable energy loss in alternating-current machines which are subject to cyclic magnetic fields. On the other hand, hysteresis is useful for creating permanent magnets or temporary magnetic memory, once the main method of providing computer Random Access Memory (RAM).

The hysteresis loop is the signature of a magnet. A slender loop indicates a good temporary magnet which has low hysteresis losses and responds readily to a small magnetic field. Temporary magnets (also known as soft magnets) are needed in magnetic circuits subject to cyclic field such as those found in motors, generators, transformers and inductors. A fat hysteresis loop indicates a permanent magnet, or hard magnet, which will remain magnetized after the application and withdrawal of a large magnetic field.

The term "hysteresis" is now used to describe any system in whose response depends not only on its current state, but also upon its past history.

1890 Tesla produced a muli-pole generator suitable for generating a high frequency carrier wave suitable for transmitting radio signals. It had 384 poles and produced a 10 kHz signal.

1891 German born, American mathematician and engineer Charles Proteus (Karl August) Steinmetz developed an empirical law for determining the magnitude of the losses due to the recently discovered phenomenon of magnetic hysteresis which he published in the magazine, "The Electrical Engineer".

The Hysteresis law for the loss of energy per magnetization cycle per unit volume "W" is given by Steinmetz's equation as:


where Bmax is the maximum flux density, η is the hysteresis coefficient or (a constant depending on the molecular structure and content of the material) and x is the Steinmetz exponent between 1.5 and 2.3, typically 1.6

Steinmetz also provided data on the magnetic characteristics of all magnetic materials then in current use.

As a rule of thumb, when the magnetic flux induced by the alternating current doubles, the hysteresis loss triples. The ability to predict the hysteresis losses for different materials and shapes enabled the design of more efficient machines, a process which had previously been trial and error.

In 1893 Steinmetz developed the phasor method using complex or imaginary number notation for representing the the varying currents and voltages in AC circuits. This simple and practical method revolutionised the analysis of AC circuits.

Called the Wizard of Schenectady where he worked for General Electric, Steinmetz also carried out research on lightning phenomena. He was a prolific inventor with over 200 patents to his name including an electric car, the 1917 Dey electric roadster, for which he designed a compact double-rotor motor which was an integral part of the rear axle avoiding the need for a differential.

Steinmetz was physically handicapped with a deformed left leg, humped back, and diminutive stature, only four foot three inches (1.3M) tall, but he was compensated by a brilliant mind, congenial personality and infectious vitality. Raised in poverty, Steinmetz was a lifelong socialist whose early political activities brought him into conflict with the German authorities resulting in his flight from Germany. Throughout his life he applied his considerable energies to helping others.

1891 Another patent for the three-phase electric power generation and transmission system, this one granted to Jonas Wenström a Swedish engineer. His patent was disputed for many years by other claimants, including Hopkinson who patented the principle in 1882. It was finally confirmed in 1959, sixty eight years after Wenström died.

1891 American electrical engineer Harry Ward Leonard introduced the motor speed control system which bears his name. For almost a century, until the advent of thyristor controllers, it was the only practical way of providing a variable speed drive system from the fixed frequency mains electricity supply.

1891 Heinrich Hertz, with his Hungarian student Philipp Eduard Anton von Lenard, discovered that cathode rays could penetrate a thin aluminium plate. Because gas could not pass through the foil they surmised that the cathode ray was a wave, publishing their results in 1894. In 1897 J.J. Thomson showed that cathode rays were streams of particles which he called corpuscles and which we now call electrons.

Lenard was awarded the Nobel Prize for Physics in 1905 for his work on cathode rays. He was a strong proponent of the German "Master Race" and became Adolf Hitler's advisor and Chief of "Deutsche Physik" or "Aryan Physics". He claimed that so called "English physics" had stolen their ideas from Germany and denounced Einstein's theory of relativity as a deliberately misleading Jewish fraud perpetrated by "Jewish physics". He was expelled from his post at Heidelberg University by the Allied occupation forces in 1945.

1891 One of the most important inventions in radio telegraphy, the coherer, was demonstrated at the French Academy of Science by physics professor from the Catholic University of Paris, Edouard Eugène Désiré Branly, and the results were published in La Lumière Èlectrique. In 1890 Branly rediscovered the coherer effect, that loose iron or similar filings would coalesce under the influence of an electric or magnetic field dramatically reducing the resistance of a path through the material. Though he was not the first to notice the phenomenon, he was the first to see its potential for detecting radio waves. His device consisted of a small glass tube containing the filings or powder in series with a battery and a galvanometer for indicating changes in the current due to the presence of an electromagnetic field. It was much more sensitive than the spark detector used by Hertz enabling transmissions over much longer distances to be detected and for a decade it became the telegraph industry standard.

Branly's design was improved by Oliver Lodge who added a trembler which shook the filings loose for decohering between signal pulses, readying the device for detecting the next pulse. Unfortunately the coherer was only suitable for detecting the reception of a pulse of radio waves such as Morse code and could not be used for detecting the varying voice signals which, Fessenden showed, could be carried on a radio wave.

Contrary to legend, neither Branly's nor Lodge's coherer was used by Marconi for his first trans-Atlantic radio transmission in 1901. This pioneering communication needed a particularly sensitive detector and this was provided by an Iron-Mercury-Iron Coherer invented in 1899 by Indian physicist Sir Jagadish Chandra Bose of Presidency College, Calcutta. It was an example of an imperfect junction coherer which reset itself after receiving a pulse so there is no need for decohering.

On the basis of his coherer design Branly is revered in France as "The Father of Radio" and some text books even credit him with a Nobel prize for the invention. In fact Branly was nominated three times for the honour but he never actually won the prize.

Prior to Branly and the invention of radio, several others had investigated variations of the coherer effect observed when loosely compacted particles or lightly touching objects were subject to electrical or magnetic fields.

  • In 1866 English engineer Samuel Alfred Varley used the coherer effect in his invention of the lightning bridge for protecting telegraph circuits and their operators. The coherer, containing loosely packed carbon granules in a wooden box, was connected in parallel to the telegraph equipment by a wire running from the telegraph line to the ground. Under normal circumstances, no electrical current could flow though the carbon granules because of their high resistance. But the high voltage between the line and the ground produced by a lightning strike caused the coherer to conduct providing a route for the lighting energy to flow to ground, thus bypassing and protecting the telegraph equipment.
  • In 1884 Italian school teacher Temistocle Calzecchi-Onesti observed that metal filings contained in an insulating tube will conduct an electrical current when influenced by electric or magnetic fields but this property disappears if the tube is shaken. He also noticed that copper filings between two copper plates had two resistance states - conducting when a high voltage was applied between the plates but and non-conducting for low voltages.

1891 German aviation pioneer Otto Lilienthal began a series of over 2000 experimental glider flights in gliders of his own design. Jumping from low hills near Berlin he was able to make flights as far as 820 feet (250 m) demonstrating that flying machines could be possible.

His gliders were similar to modern hang gliders but with a limited range of control made possible by the pilot changing the centre of gravity by shifting his body. Designs were based on Cayley's theories and his own observations of bird flight and he made both monoplane and biplane versions.

In 1889 He published a book Birdflight as the Basis of Aviation outlining his own theories and experiences of flight which has become an aviation classic.

Tragically, in 1896, at the age of 48 while piloting his regular glider he failed to recover from a stall and fell 49 feet (15 m) to the ground, dying from his injuries 36 hours later in hospital.

His last words were "Opfer müssen gebracht werden!" roughly translated as "Victims are necessary" or "Sacrifices must be made."

1892 British born American chemist Edward Weston invented and patented the saturated cadmium cell. Known as the Weston Standard Cell, it was adopted as the International Standard for electromotive force (EMF) in 1911 and was used as a calibration standard by the US National Bureau of Standards for almost a century. It had the advantages of being less temperature sensitive than the previous standard, the Latimer Clark Standard Cell which it replaced and of producing a voltage of 1.0183 Volt, conveniently near to one Volt. Similar to Clark's cell it used a Cadmium anode rather than Zinc.

He had revolutionised the electroplating industry in 1875 by replacing the batteries used to provide the current used in the plating process with dynamos which he designed and made himself and in 1886 he developed a practical precision, direct reading, portable instrument to accurately measure electrical current, a device which became the basis for the moving coil voltmeter, ammeter and watt meter.

A prolific inventor Weston held 334 patents.

1892 Eccentric Kentucky melon farmer Nathan B. Stubblefield "demonstrated" wireless telephony using a ground battery or earth battery (first proposed by Bain in 1841), for transmitting signals through the ground. Extravagant claims were made for the applications of the ground battery, from telephony and broadcasting to power generation, but they were never substantiated and Stubblefield, claiming he was swindled, died of starvation, an impoverished recluse. He is honoured in his hometown of Murray, Kentucky as "The Real Father of Radio".

1892 Dutch physicist Hendrik Antoon Lorentz formulates Lorentz Law, a fundamental equation in electrodynamics which gives the force F on a charged particle in an electromagnetic field as the sum of the electrical and magnetic components as follows:

F = qE + qv X B

Where q is the charge on the particle, v is its velocity, E is the electric field and B is the magnetic field.

Lorentz developed a mathematical theory of the electron before their existence was proven for which he received the Nobel Prize in 1902

1893 Two German schoolmasters Johann Phillip Ludwig (Julius) Elster and Hans Friedrich Geitel discovered the sensitive photoelectric effect of alkaline metals such as sodium or potassium in vacuum tube at visible light spectrum. They later design the first practical photoelectric cell or "electric eye" which provides a voltage output which varies in relation to the intensity of light impinging upon it. They decline to patent their invention. The photoelectric effect is the basis of all electronic image tubes.

1893 Contract to supply hydroelectric generators to harness the power of Niagara Falls using Tesla's AC system awarded to Westinghouse, signalling the beginning of the end for DC generation and transmission, the end of the Current Wars and a triumph for Tesla. Rival Edison had lined up influential backers including J. P. Morgan, Lord Rothschild, John Jacob Astor IV, W. K. Vanderbilt and initially Lord Kelvin, a proponent of direct current, who headed an international commission to choose the system. After seeing Tesla's AC system which was used to light the 1893 World's Columbian Exposition at Chicago, Kelvin was converted to a be supporter of the AC system.

The system was completed in 1895 with three enormous 5,000 horsepower generators supplying 2,200 Volts for local consumption, stepped up to 11,000 Volts for transmission to Buffalo 22 miles away. The capacity was later increased to 50,000 horsepower with 10 generators and the transmission Voltage increased to 22,000 Volts for longer distance transmission.

1893 French born American railway engineer and aviation pioneer Octave Chanute organised an International Conference on Aerial Navigation at the World's Columbian Exposition in Chicago. He was an enthusiastic and influential promoter of aviation developments and 1894 he published Progress in Flying Machines a survey of all published research into fixed-wing heavier-than-air aviation developments up to that date. The book became a bible for all would-be aviators at the time.

1893 German engineer Rudolf Christian Karl Diesel, born in Paris of Bavarian parents, published a paper entitled "Theorie und Konstruktion eines rationellen Wärmemotors zum Ersatz der Dampfmaschine und der heute bekannten Verbrennungsmotoren" - "Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and Combustion Engines Known Today" in which he described his ideas for the compression ignition internal combustion engine, now known as the Diesel engine. The following year he applied for a patent for the engine. The German company Maschinenfabrik Augsburg Nürnberg AG (MAN) gave him the opportunity to test and develop his ideas.

At the request of the French Government who were looking for locally produced fuels for their African colonies, the Otto Company demonstrated at the Paris Exhibition in 1900, a small Diesel engine running on pea-nut oil, the first bio-diesel. Diesel himself also investigated and promoted the use of alternative fuels in his engines. Compression ignition engines using the Diesel cycle are today taking market share form the more popular spark ignition Otto cycle engines due to their superior efficiency.

Similar compression ignition engines had already been built in 1886 by English inventor Herbert Akroyd-Stuart for which he applied for a patent in 1890 entitled "Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air"

Diesel's inspiration was a modernised version of the ancient Chinese "Firestick" which was used as a cigarette or gas lighter. A piece of tinder was held in a glass tube containing a plunger. When the plunger was forced rapidly into the tube, as in a bicycle pump, the heat of compression would ignite the tinder.

On an apparently normal business trip from Belgium to attend, as guest of honour, the opening of a new Diesel engine factory in England in 1913, Diesel mysteriously disappeared from a cross Channel steamer. His body was recovered from the sea ten days later, but his death has never been satisfactorily explained. Speculation ranges from suicide, (He was thought to be in financial difficulties, though he was about to secure a new royalty stream), through accident, to assassination (On the verge of the First World War, agents of Imperial Germany possibly did not want him to allow the "allies" access to his patents).

See also Heat engines.

1894 The first ever radio signal was sent 55 metres from one building to another in Oxford during the 1894 meeting at the British Association for the Advancement of Science about the work of Hertz who had died earlier that year. The lecture and demonstration were given by British physicist Oliver Joseph Lodge who arranged the transmission of the Morse code like signals which were transmitted by electrical engineer Alexander Muirhead and detected by Lodge using a modified Branly coherer rather than Hertz's spark gap. The sender used a telegraph key to send a pulse and the coherer in the receiver caused a bell to ring. It was just like a telegraph link but without the interconnecting wire. Lodge later formed a business partnership with Muirhead to commercialise a number of fundamental radio technology inventions which they had patented.

In 1911 they sold their patents, one of which was Lodge's patent for the tuned circuit to radio pioneer Guglielmo Marconi.

Lodge was knighted for his contribution to physics but much of his later life was devoted to his interest in the paranormal, "life after death" and spiritualism about which he wrote several books.


1895 German physicist Wilhelm Conrad Röntgen experimenting with a Crookes tube accidentally discovered X-rays, high frequency electromagnetic radiation, while investigating the glow from the cathode rays. He gave his preliminary report "Uber eine neue Art von Strahlen" to the president of the Wurzburg Physical-Medical Society, accompanied by experimental radiographs and by the image of his wife's hand. Within three years, every major medical institution in the world was using X-rays. Röntgen, who won the first Nobel prize in physics in 1901, declined to seek patents or proprietary claims on the use of X-rays.

Röntgen used a very high voltage to accelerate the electrons in a high speed electron beam and X-rays were produced when the beam was suddenly decelerated when it hit the target electrode. These rays had a continuous frequency spectrum and are now called bremsstrahlung radiation, or "braking radiation".

Characteristic X-rays on the other hand have a spectrum with definite energy levels which are produced when electrons make transitions between characteristic atomic energy levels in heavy elements.

X-ray technology is now widely used in materials science. See Bragg (1912)

1895 French physicist Pierre Curie discovered that the magnetic coefficients of attraction of paramagnetic bodies vary in inverse proportion to the absolute temperature -- Curie's Law. He showed that ferromagnetic materials exhibit a characteristic temperature, now called the Curie point or Curie temperature, above which they lose all their magnetic properties. He also showed that there is no temperature effect for diamagnetism.

1895 Alexandr Popov, an instructor at the Russian Imperial Navy's torpedo school, experimented with a variety of antennas (aerials) to capture electromagnetic radiation from lightning discharges. His receiver consisted of a coherer between an aerial wire connected to a tall mast and an earth (ground) wire connected to water pipes to detect the radiation, he successfully proved that the discharge emits electromagnetic waves. His experiment did not include a transmitter.

In 1890 he had repeated Hertz' experiments for the benefit of his students and in 1896, at a meeting of the Russian Physical-Chemical Society, he repeated Lodge's 1894 demonstration of radio signalling by sending the Morse coded message "Heinrich Hertz" over a radio link. Like Lodge, Popov was more interested in pursuing theoretical physics than in commercialising the idea, leaving the door open to the less technically competent but more commercially astute Marconi. (See following item). In later years the existence of these experiments was used to justify the claim by Popov's supporters that he was "The Father of Radio".

1896 Inspired by Hertz, 22 year old Italian Marchese Guglielmo Marconi, son of the Irish-born heiress to the Jameson whiskey fortune, was granted his first patent (in England) for radio telegraphy using Hertzian waves. This was claimed to be the first application of radio waves and the first to show that practical radio communications were possible. But Marconi had basically just patented the system demonstrated by Lodge two years earlier, and the principle of radio communications. Though he had been helped by William Preece, the Chief Engineer of the British Post Office, and his staff, Marconi himself added little to the system which was the radio equivalent of Morse's telegraph, which just switched the radio wave on and off in "dots and dashes", and did not carry voice signals. Because Marconi's "invention" was enclosed in a box, the patent office did not consider the technology to be in the public domain and so granted the patent. Lodge and Preece had been kept in the dark about the patent application and felt deceived.

It was Fessenden who first carried voices over the radio waves ten years later. Marconi was a great promoter, he developed transmitters, receivers and antennas and his telegraph systems were soon in use throughout the world, spanning the Atlantic in 1901, and earning him fame and fortune. He was awarded the Nobel prize for physics in 1909.

See also Wireless Wonders.

1896 American engineer William W. Jacques developed a carbon battery producing electricity directly from coal. 100 cells with carbon electrodes and alkaline electrolyte were placed on top of a coal fired furnace that kept the electrolyte temperature between 400-500 °C and air was injected into the electrolyte to react, he thought, with the carbon electrodes. The output was measured as 16 Amps at 90 Volts. Initially, Jacques claimed an 82 percent efficiency for his battery, but he had failed to account for the heat energy used in the furnace and the energy used to drive an air pump. The real efficiency was a meager 8 percent. Further research demonstrated that the current generated by his apparatus was not obtained through electrochemical action, but rather through thermoelectric action.

1896 Antoine Henri Becquerel discovered radioactivity when Uranium crystals wrapped in paper and left in a drawer with photographic plates created an image of the crystals on the plates. Radioactivity is the spontaneous breakdown of unstable atomic nuclei resulting in the emission of radiation which may be alpha particles (Helium nuclei), beta particles (electrons), nucleons (neutrons or protons), or gamma rays (high energy electromagnetic radiation). At the time however the nature of these mysterious rays was not known and it was several years before Rutherford and others were able to identify the content of the radiation.

Radioactivity can come from the decay of naturally occurring radioisotopes. Nuclear batteries are designed to make use of the radiated energy of certain radioactive isotopes by converting it into electrical energy.

Becquerel came from a distinguished family of scholars and scientists. His father, Alexandre-Edmond Becquerel, was a Professor of Applied Physics, discovered the photovoltaic effect and had done research on solar radiation and on phosphorescence, while his grandfather, Antoine César Becquerel, had been a Fellow of the Royal Society and invented a non polarising battery and an electrolytic method for extracting metals from their ores.

1896 In the USA, the flashlight or torch was invented by David Misell. The original versions were designed to attach to a tie or scarf and were sold by a Russian immigrant, Conrad Hubert in his novelty shop where Misell went to work. Although portable battery powered lamps had been in use in the UK since 1881 where they were patented by Burr and Scott, the first flashlight as we know it today introduced by Hubert in 1898. It was designed by Misell and was powered by a "D" cell which, with the light bulb and a rough brass reflector, was contained in a paper tube. Hubert went on to found Ever Ready and patents for subsequent flashlights although designed by Misell were awarded to Hubert.

The invention of the tungsten filament lamp by Coolidge in 1910 greatly improved the performance of the torch which in turn created a growing market for batteries, popularising the "D" cell format we still use today.

1896 H. J. Dowsing patented the electric starter which he fitted to a modified Benz motor car purchased from maker Walter Arnold who made them under licence as the Arnold Sociable in East Peckham, Kent. Dowsing's starter consisted of a dynamotor, coupled to a flywheel, which acted as a dynamo to charge the battery and as a motor when needed to start the engine, an idea recently rediscovered as the integrated starter alternator (ISA). The first production electric self-starter was produced by Dechamps in Belgium in 1902.

1896 American astronomer, inventor, secretary of the Smithsonian Institution, professor Samuel Pierpoint Langley successfully launched a series of unmanned gliders to demonstrate the potential for controlled flight in a heavier than air machine. They were launched from a boat on the Potomac River and one of these flew over 4000 feet (1220 m) while another covered 5000 feet (1525 m). To test his theories and designs he constructed a version of Cayley's "whirling-arm apparatus" to measure the aerodynamic forces on models as they were propelled at high speed through the air. He investigated various wing profiles and showed that even a brass plate could be kept aloft if its speed through the air was high enough from which he concluded that a heavier than air machine would be viable.

Based on the success of his models, in 1898 Langley received a grant of $50,000 from the US War Department and a further $20,000 from the Smithsonian to develop a manned airplane, which he called an "aerodrome" (Greek - aeros "air" and dromos, "road" or "course").

To save weight, Langley's airplane had no landing gear so it was designed for catapult launching and landing over water. It had pitch and yaw control but no roll control and a 50 horsepower engine, more than four times the power of the engine used in the Wright Flyer. The airframe of the plane was very flimsy and the engine was very heavy, - too heavy. It was ready in 1903 but it made only two flights, one in on October 7 and one on December 8, both of which ended in crashes before the plane got airborne. In the second crash the plane broke up dumping the pilot on the Potomac leaving half of the plane still on the launching boat and the other half in the river. With the benefit of perfect hindsight, the army, who had paid for the plane and witnessed the tests, announced that the reason for the failure was that the propellers were too small.

The newspapers revelled in Langley's misfortune, particularly the New York Times. After the first crash of what they called Langley's "airship", they offered their opinion that it would be at least 1000 years before man could devise a flying machine, basing their prediction on the principles of evolution. After the second crash they advised Langley to give up and stick to his academic pursuits.

One week later, the Wright brothers made the first successful controlled flight of a heavier than air machine.

NASA's Langley Research Centre at Hampton, Virginia is named in Langley's honour.

Langley also invented the bolometer in 1878.

1897 British physicist Joseph John (J J) Thomson working at the Cavendish Laboratory in Cambridge investigating the affect of magnetic fields on cathode rays in a Crookes tube discovered the electron and calculated the ratio between its charge and its mass, the e/m ratio. He determined that they were identical particles no matter what metal had emitted them and that they were the universal carriers of electricity and a basic constituent of matter. He also calculated the velocity of the electron in the cathode ray to be 1/10 of the speed of light. J.J. Thomson was awarded the Nobel prize in 1906 for his studies on the conduction of electricity through gases and for the discovery of the electron and his pioneering work on the structure of the atom.

At the time there was great rivalry between German researchers who believed cathode rays to be waves and their British counterparts who believed them to be particles. In one of the greatest ironies of modern physics J.J. Thomson was awarded the Nobel Prize for showing that the electron is a particle, while his son, George Paget Thomson later received the Nobel prize for proving that the electron was in fact a wave.

Seven of Thomson's students went on to gain Nobel prizes in their own right.

Thomson died in 1940 and in his lifetime he never drove a car or travelled in an aeroplane. He had a passion for nature and said that if he had to live his life over again he would be a botanist.

Ever since Faraday published his work on the magnitude of the weights of the products of electrolysis in 1833, experimenters had postulated the idea that electric current was carried by corpuscles or particles but none had been able to isolate or describe such particles. By the late 1890's however, several other investigators working contemporaneously with Thomson had identified the charged particle we now call the electron and calculated the e/m ratio just as Thomson did in April 1897. These included Pieter Zeeman at the University of Leiden who in 1896 observed the spreading of spectral lines caused by the influence of a magnetic field and concluded that the light waves were produced by the movement of ions. From the experiment he was able to calculate the e/m ratio. At the same time, each working independently with cathode rays, Emil Weichert at the University of Köningsburg, Walter Kaufmann at the University of Berlin and Philipp Lenard an assistant of Heinrich Hertz carrying on Hertz' experiments after his death, all published similar results for the value of the e/m ratio early in 1897. It was Thomson however who identified the electron as a sub atomic particle, while the others were hampered by trying to reconcile the evidence of a particle with the notion of the aether.

History is kind to the winners of Nobel prizes. Once conferred, the other participants in the race are forgotten.

1897 The first oscilloscope using a cathode ray tube (CRT) scanning device was invented by the German scientist Karl Ferdinand Braun. He made many contributions to radio technology including antennas and detectors. He was awarded the Nobel prize with Marconi in 1909 for this work. During the first World War he was interned by the US government as an enemy alien and died before the war ended.

1897 Regenerative braking first used on a car to recharge the battery by M. A. Darracq in Paris.

1897 Russian mathematics teacher, Konstantin Eduardovich Tsiolkovsky, built a wind tunnel in his apartment which he used to explore aerodynamics and the drag characteristics of different shapes. During the same year he also developed the fundamental Theories of Rocket Motion which he published as "The Exploration of Cosmic Space by Means of Reaction Devices". In it he showed that a rocket's velocity is proportional to its effective exhaust velocity and he defined the Specific Impulse, which became the standard measure for comparing the energy produced by rocket engines and propellants.

He defined the Specific Impulse (I), expressed in seconds, as follows:

I = F / (dm/dt)

Where F is the rocket thrust in pounds and dm/dt is the propellant consumption in pounds per second.

Alternatively this can be written in terms of the rocket exhaust velocity ve as follows:

I = ve / g

Where g is the acceleration due to gravity (32 f/sec/sec)

He also showed that the change δv in velocity of a rocket as it consumes its fuel is given by:

δv = veLn(m0/m1)

Where ve is the exhaust velocity, m0 is the initial total mass, including propellant, m1 is the final total mass and ln is the natural logarithmic function.

This is known as the Tsiolkovsky Equation

It can also be expressed in terms of the Specific Impulse of the fuel as follows:

δv = I.g

With these relationships he was able to compare the effectiveness of different fuels, to calculate thrust and flight velocity as a function of fuel consumption and to show the influence of gravity during vertical ascents.

In 1903 he published a summary of studies he had carried out into liquid fuelled rockets and the optimum shape for rocket exhaust nozzles and he proposed the ideas of fuel pumping systems, regenerative cooling and directional control by means of rudders in the exhaust stream all of which were first successfully introduced on the German V-2 rocket forty years later.

In 1911 he confirmed the Earth's Escape Velocity to be 25,000 miles per hour and calculated the Orbital Velocity for Earth Satellites to be 17,800 miles per hour. See also Entering Space.

He had a keen interest in space travel and published many works on space stations and life support systems. He also developed the concept of the Multi-stage Rocket, which he called a "rocket train", to achieve higher velocity and range with the same initial vehicle weight, payload weight and propellant capacity or alternatively to carry a greater payload with a smaller initial weight. By jettisoning the propellant tanks and engines of the first stages once the propellant is used up, the later stages to not have to waste energy in accelerating a useless mass.

Tsiolkovsky's early works were the first academic studies on rocketry but unfortunately they were published in Russian and at the time they did not achieve a high circulation in the international scientific community. Despite his interest and the wide ranging scope of his contribution to the science, he never built any rockets.

See also Rocket propulsion

1897 German researcher W. Peukert discovered that the faster a battery is discharged the lower its available capacity, a phenomenon for which he developed the empirical law C = IT known as the Peukert Equation where "C" is the theoretical capacity of the battery expressed in amp hours, "I" is the current, "T" is time, and "n" is the Peukert Number, a constant for the given battery. A similar phenomenon occurs when a battery is charged. See also charging times for an explanation and a beer analogy.

1898 Danish telephone engineer Valdemar Poulsen patented the Telegraphone, the first magnetic recording and playback apparatus. It used a magnetised wire as the recording medium.

1898 The Proton discovered by German physicist Wilhelm Wien. Using an apparatus designed by Goldstein which generated canal rays of positively charged particles he determined that canal rays were streams of protons with mass equal to the mass of a Hydrogen atom. Rutherford later coined the word proton in 1919.

Wien also discovered the inverse relationship between the wavelength of the peak of the emission of a black body and its temperature now called Wien's Law. He was awarded the Nobel Prize in 1911 for his work on Black Body Radiation.

1898 Oliver Lodge patented the principle of tuned circuits which he called "syntonic tuning" for generating and selecting particular radio frequencies. This is the basis of selecting a single desired radio station from all those which are transmitting by tuning the receiver to the transmitter. Not only was this more efficient, it was fundamental to the orderly use of the radio spectrum and the establishment of practical radio communications systems which did not interfere with eachother.

1898 Pierre and Marie Sklodowska Curie discovered Radium named from the Latin "radius" meaning "ray" and Polonium which Marie named after her native Poland. With very limited resources, during the course of four years, the Curies refined 8 tonnes of waste pitchblende to produce 1 gram (0.04 ounces)of pure Radium Chloride. (It was not until 1911 that she was able to isolate pure Radium). Radium is over one million times more radioactive than the same mass of Uranium and one gram of Radium releases 4000 kilo joules (1.11 KWh) of energy per year. In 1900 they showed that beta rays and cathode rays are identical. Unaware at the time of the dangers of radiation in 1903 they both began to show signs of radiation sickness. Marie shared the 1903 Nobel Prize for Physics with her husband Pierre and Henri Becquerel for the investigation of radioactivity, a phenomenon which she named. In 1906 Pierre was unfortunately killed when he was run over by a horse drawn cart. Marie continued their investigations and in 1911 was awarded a second Nobel Prize, this time for Chemistry for her discovery of two new elements.

Despite her achievements and her two Nobel prizes, she was rejected by the French Academy of Sciences when seat for a physicist became vacant. During her life she worked tirelessly for humanitarian causes and the use of X-rays and radioactivity in medical research, refusing to patent any of her ideas. She died of leukaemia caused by prolonged exposure to radioactivity. Her laboratory notebooks are still considered too radioactive to handle and photographic films, when placed between the pages, show the images of Madame Curie's radioactive fingerprints when developed. A year after her death, her daughter Irene won the family's third Nobel Prize.

1899 Charles H. Duell Commissioner in the US Office of Patents announced "Everything that can be invented has been invented"

1899 Working at McGill University in Montreal on Becquerel's mysterious rays, New Zealand physicist Ernest Rutherford, assisted by English chemist Frederick Soddy, discovered two kinds of "rays" emanating from the Uranium, one of which he called the alpha rays, could be absorbed by a sheet of writing paper. The other which he called beta rays was one hundred times more penetrating but could be stopped by a thin sheet of aluminium. Meanwhile in 1900, French physicist Paul Ulrich Villard found that Radium emitted some far more penetrating radiation, which he christened gamma rays. These rays could penetrate several feet of concrete.

It was still some time before the properties of all these different rays could be determined.

  • By 1900 Becquerel succeeded in deflecting the beta rays with a magnetic field proving that the rays were in fact streams of charged particles. He also measured the e/m ratio of the particles which turned out to be close to that of cathode rays suggesting that the beta rays were in fact streams of electrons.
  • It was not until 1903 that Rutherford was able to deflect the alpha rays and it was 1905 before he could measure the e/m ratio. His results showed that the rays were in fact particles with the opposite charge from an electron. He concluded that if the charge on an alpha particle was the same as that on a hydrogen ion, the mass of the alpha was approximately twice that of the hydrogen atom. In 1908, he finally established that the alphas were helium atoms with two electrons missing, carrying charge 2 e , and having mass four times that of the hydrogen atom.
  • Gamma rays were not deflected by a magnetic field which showed them to be rays and not particles. They were found to be similar to x-rays, but with much shorter wavelength. This was not settled until 1914, when Rutherford observed them to be reflected from crystal surfaces.

1899 First patent on Nickel Cadmium rechargeable cells using alkaline chemistry taken out by Waldemar Jungner of Sweden. The first direct competitor to the Lead acid battery.

1899 The world land speed record of 68 mph was set by a Belgian built electric car, the "Jamais Contente", designed and driven by Camille Jénatzy. The first to exceed 100 kph, his cigar shaped car was powered by two 80 cell Fulmen Lead acid batteries supplying two twelve volt, 25 kilowatt motors, integral with the rear axle, driving the rear wheels directly.

Jénatzy, known as the Red Devil because of his red beard, was a famous racing driver at the time when racing was very dangerous, however his life was ended at his country estate rather than on the race track when, hosting a shooting party, he sneaked into the woods to imitate a roaring bear and was shot by one of his friends.

1899 Young German engineer Ferdinand Porsche, working at the Jacob Lohner Company, built the first Hybrid Electric Vehicle (HEV), a series hybrid, optimised for simplicity and efficiency. It used a petrol engine rotating at optimum, constant speed to drive a dynamo which charged a bank of batteries which in turn provided power to hub mounted electric motors in the front wheels. 300 Lohner Porsches were produced.

1899 Serbian immigrant Mihajlo (Michael) Idvorski Pupin filed for a patent (granted in 1900) for the Pupin inductive loading coils which are used to cancel out distortion due to the distributed capacitance in long transmission lines. The idea which was originally proposed, but not patented, in 1887 by Oliver Heaviside made Pupin very wealthy and destroyed Heaviside. Far from recognising his debt to Heaviside, he chose instead to belittle his contribution.

Not content with stealing Heaviside's ideas, Pupin played the same trick on Oliver Lodge who patented the tuned circuit for selecting radio waves in 1898. In his autobiography Pupin disingenuously claimed to have invented the tuned circuit in 1892 after being inspired by the way Serbian bagpipers tuned their pipes. Strangely Pupin did not patent the idea at the time but he did receive a patent or "Electrical transmission by resonance circuits" in 1900.

Pupin arrived in the United States as a young penniless immigrant. He studied at Columbia University where he made improvements to X-ray photography and radio wave detection eventually rising to be emeritus professor.

1900 Thomas Alva Edison in the USA also patents a rechargeable alkaline cell, the Nickel Iron (NiFe) battery. Another one of Edison's 1093 patents.

Nickel Iron batteries were very robust, designed for powering electric vehicles, but with the rise of the internal combustion engine their main applications became railway traction, fork lift trucks and utilities.

1900 Sales of internal combustion engined cars overtake sales of electric cars for the first time. More than half the world's cars are EVs.

1900 German physicist Max Planck announced the basis of what is now known as quantum theory, that the energy emitted by a radiating body could only take on discrete values or quanta. Planck's concept of energy quanta conflicted fundamentally with all past classical physics theory and eventually gave birth to the particle theory of light as later explained by Albert Einstein. Although its importance was not recognised at the time, quantum theory created a revolution in physics. Planck was driven to introduce it strictly by the force of his logic; he was, as one historian put it, a reluctant revolutionary.

The energy E in a quantum of light, now called a photon, or resonator of frequency ν is where h is a universal constant equal to 6.63 X 10-34 Joule seconds (Js), now called Planck's constant.

He was awarded a Nobel prize in 1918 for his work on quantum theory.

See more about Photon Energy

Planck's personal life was a tragic one. His first wife died early leaving Planck with two sons and twin daughters. The elder son was killed in action in 1916 in the First World War. Both of his daughters died in childbirth. World War II brought further tragedy. Planck's house in Berlin containing his technical papers was completely destroyed by bombs in 1944. Far worse his younger son died while being tortured by the Gestapo after being implicated in the attempt made on Hitler's life in 1944. Planck died in 1947 at the age of 88.

1900 German physicist Paul Karl Ludwig Drude developed a model to explain electrical conduction based on the kinetic theory of electrons moving through a solid.

1900 Belgian car maker, Pieper, introduced a 3½ horsepower "voiturette" another variant of the hybrid electric vehicle (HEV). An electric motor/dynamo was mounted in line with a small petrol engine and acted as a generator during normal driving, recharging the batteries. For hill climbing the motive power was augmented by battery power as the electric motor was switched to supplement the power of the engine.

Later versions used higher capacity batteries (28 Tudor batteries in series) and a 24 horsepower engine connected to a higher power electrical drive via a magnetic clutch. The clutch mechanism allowed energy to be recovered by regenerative braking as well as the use of the higher power electric motor to drive the vehicle on its own.

1900 Irish born American John P. Holland launched his first submarine the Holland I in 1878. A crude design, carrying a crew of one, it was powered by a petrol engine and ran on compressed air when submerged. Holland was a sympathiser of the Fenian Brotherhood, an Irish revolutionary secret society, forefathers of the IRA, founded in the United States. He designed the Fenian Ram, a three man submarine which was launched in 1881, for attacking British shipping. Finding the Fenians unreliable customers he made several unsuccessful attempts to sell his submarines to the US government, eventually launching his sixth submarine the Holland VI in 1898. It was a dual propulsion submarine the which used a 45 h.p. Otto petrol engine for propulsion and battery charging while on the surface and a 110 Volt electric motor powered by 60 Lead Acid cells with a capacity of 1500 ampere hours for propulsion when submerged. This time his demonstration was successful and the submarine was purchased by the US government. It was commissioned in 1900 and renamed the USS Holland, also known as the SS1, becoming the US Navy's first submarine. Although it carried a crew of only five plus an officer, the Holland VI was a major breakthrough in submarine design. For the first time, all the major components were present in one vessel - dual propulsion systems, a fixed longitudinal centre of gravity, separate main and auxiliary ballast systems, a hydrodynamically advanced shape, and a modern weapons system. The configuration and design principles used in the Holland VI remained the model for all submarines for almost 50 years.

1901 Patent granted to Michaelowski in Russia for the rechargeableNickel Zinc battery.

1902 The Mercury Arc Rectifier invented by American engineer Peter Cooper Hewitt. A spin off from developments of the mercury arc lamp it was capable of rectifying high currents and found use in electric traction applications which used DC motors.

1902 Twenty years after the introduction of electricity supply in the USA only 3% of the population were served by electricity.

1903The invention Electrocardiograph by Indonesian born Dutchman Willem Einthoven was announced after a long gestation period. Building on Waller's work of 1887 (and the contributions of many others following in the footsteps of Galvani) it used a sensitive "string galvanometer" of Einthoven's own design to pick up small electrical currents from the patient's torso and limbs. (Galvani's theories about Animal electricity vindicated?)

Einthoven is now credited with the design of the electrocardiograph for which he received the Nobel Prize in 1924.

1903 On December 17th at Kitty Hawk, North Carolina, American inventors Wilbur and Orville Wright made the first controlled, powered flights in an airplane which came to be known as the Wright Flyer which they had designed and made themselves. They made two flights each. The first flight, piloted by Orville, lasted 12 seconds and covered a distance of 120 feet (37 m). The fourth flight of the day was piloted by Wilbur and lasted 59 seconds covering a distance of 852 feet (260 m) on a straight flight path.

The brothers were sons of a minister, Bishop Milton Wright of the United Bretheren Church and led very correct lives. They neither smoked, drank nor married and lived at home with their parents and always wore conventional business suits even while working on their machines. They ran a small bicycle building and repair business and in their spare time were enthusiastic participants in the sport of gliding which was popular at the time. Neither of them had more than a high school education, Orville dropped out in his junior year and Wilbur did not graduate, yet with only very limited resources and training they showed great scientific ingenuity and professionalism.

In 1901 they decided to apply their mechanical skills and their gliding experience to building a powered flying machine. They were familiar with the works of Smeaton, Cayley, Lilienthal, Chanute and Langley and building on this knowledge they conducted extensive tests to confirm their theories while investigating their own improvements. Key innovations which they introduced were:

  • The use of a wind tunnel which they built themselves to verify Smeaton's lift equation and to determine the aerodynamic efficiency of their designs. It provided more representative, smooth air flow enabling more accurate measurements than Smeaton's whirling arm which stirred and whipped up the ambient air as it rotated so that the model passed through moving, turbulent air instead of the desired still air causing a velocity offset as well as a degree of uncertainty in the measurements. Balance springs were used to measure the aerodynamic forces on the models. The wind tunnel was used to investigate the lift and drag of over 200 wing profiles and also to optimise the design of the propellers. They also extensively flight tested various structures as kites or gliders to determine their lift, stability and controllability.

  • They were the first to design their propellers with a cross section in the form of an aerofoil and achieved peak aerodynamic efficiencies of 82%, only slightly less than the 85% efficiency of a modern wooden propeller.

  • Conscious of the accidents which had taken the lives of Otto Lilienthal, and more recently English glider pilot Percy S. Pilcher, they realised the importance of maintaining the stability of the aircraft. With this in mind they devised methods to control roll, pitch and yaw to give the aircraft full manoeuvrability and their Wright Flyer was the first to incorporate this 3 axis control.
    • Pitch control was relatively easy to implement by means of an elevator (winglet), mounted in a canard configuration in front of the aircraft. It's angle of attack could be varied by the pilot enabling the pilot to climb or dive.
    • Similarly a rudder in the tail provided a simple method of yaw control enabling the aircraft execute a turn.
    • Roll control however was more difficult. From their observations of birds they concluded that birds made their bodies roll right or left by changing the angle of the ends of their wings. They replicated this control on their machine by attaching lines to the corners of the wings to twist or warp the wings when required to increase or decrease lift on the outer sections of the wings so that the aircraft could "bank" or "lean" into the turn just like a bird (or a bicycle). The plane was turned by a coordinated use of the yaw and roll controls.

  • The remaining design challenge was to construct a powerful but lightweight engine, a goal which had eluded many would be aviators in the past leaving them stuck on the ground. To save weight the brothers designed a very rudimentary engine which had neither fuel pump, oil pump, water pump, carburettor, spark plugs, battery, radiator, starter motor nor throttle. Weight was further reduced by the use of an aluminium crank case, the first use of this metal in aircraft construction.
  • The engine, which was made locally, had four horizontal inline cylinders with a total capacity of 202 cu in (3.3 litres) in a cast iron block and produced 12 horsepower from a four stroke cycle giving an acceptable safety margin over the minimum of 8 horsepower that they calculated to be necessary. It was placed on the lower wing next to the pilot and was connected by means of bicycle chains to two counter-rotating propellers located behind the wings in a "pusher" arrangement.

    In operation, petrol was gravity fed from a small tank with a capacity of 1.5 quarts (1.4 litres), mounted on a strut above the engine, and mixed with air in a shallow chamber next to the cylinders. Heat from the engine vaporised the fuel-air mixture, causing it to expand through the intake manifold where it was drawn into the cylinders.

    Ignition was produced by two contact breaker points in each combustion chamber which were opened and closed by a camshaft. The engine was started by means of a separate external coil and four dry-cell batteries, not carried on the aircraft, which generated the initial spark. The electric charge to generate the sparks while the engine was running was provided by a low-tension magneto.

    Cooling was by means of a water jacket surrounding the engine, gravity fed from another small tank above the engine. The water was not circulated. Instead the reservoir simply replenished the water which evaporated from the water jacket which as an integral part of the crank case casting. Lubrication of the internal engine components, the crankshaft and pistons, was by the splash method while a hand held oil can was used to oil the external components such as the camshaft and the bicycle chains.

    The engine weighed 180 pounds (82 Kg) dry weight and the total weight of the aircraft was 700 pounds (318 Kg).

  • The need for pilot skills was not overlooked. They themselves made over 1000 flights on a series of gliders at Kitty Hawk between 1900 and 1902 to develop their skills and were at the time the most experienced pilots in the world.

The entire project cost less than $1000 which Wilbur and Orville paid out of their own pockets. Not a bad result for a couple of country boys.

By contrast, a similar attempt at powered flight took place just one week earlier when Washington insider, Prof. Samuel Langley's flying machine, funded by grants of $50,000 from the US government and $20,000 from the Smithsonian Institution, was unable to get off the ground and ended up unceremoniously in pieces in the Potomac (its intended landing point).

While Langley's failures hit the headlines, the Wright brothers' momentous flight was largely ignored by most of the press including the Scientific American and New York Times, perhaps chagrined by their inaccurate prediction only a few days previously. As late as 1905 they were still suggesting that it was a hoax and in 1906 a headline about the Wrights in the International Herald Tribune proclaimed "FLYERS OR LIARS?".

On October 5, 1905 in the third, improved, Wright Flyer, Wilbur made a circling flight of 24 miles (38.9 km) in 39 minutes 23 seconds over Huffman Prairie, Dayton, Ohio, returning to the point of takeoff, conclusively demonstrating the plane's manoeuvrability.

1903 Following on from their work on radiation, Soddy and Rutherford proposed that the phenomenon of radioactivity was due to the spontaneous atomic disintegration of unstable heavy elements into new, lighter elements, an idea which, like many new scientific theories, was treated with derision at the time.

Soddy was a chemist and Rutherford a passionate physicist who believed that chemistry was an inferior science to physics. Ironically it was Rutherford rather than Soddy who was honoured in 1908 with the Nobel Prize for chemistry for the discovery of radioactive transformation. Afterwards Rutherford liked to joke that his own transformation into a chemist had been instantaneous. Soddy resented the the fact that his contribution had not been recognised. He was however eventually awarded a Nobel prize in 1921 for his work on isotopes but that did little to mitigate his earlier slight.

1903 British Patent awarded to German Albert Parker Hanson, living in London, for flexible printed wiring circuits intended for use in telephone exchanges. Based on flat parallel copper conducting strips bonded to paraffin waxed paper. The design used a double layer construction with the copper strips in alternate layers perpendicular to the layer below forming a rectangular grid. Interconnections were crimped through holes in the paper. As well as through hole connections, Hanson's patent also described double-sided and multi-layer boards.

1903 The Compagnie Parisienne des Voitures Electriques produced the Krieger front wheel drive hybrid electric vehicle (HEV) with power steering. A petrol engine supplements the battery pack.

1903 Russian botanist Mikhail Semenovich Tswett invented the technique of chromatography (Latin "colour writing") which he demonstrated by passing extracts of plant tissue through a chalk column to separate pigments by differential adsorption. It was derided at the time but the principle is now used universally for separating and identifying different chemical compounds from samples.

1903 The teleprinter machine (a.k.a. teletypewriter, teletype or TTY) invented by New Zealand sheep farmer Donald Murray. It could punch or read five digit Baudot coded paper tapes (Murray used his own modified version) and at the same time print out the message on a sheet of paper. It de-skilled the telegraph operator's job, since they no longer needed to know Morse code, and at the same time greatly speeding data communications. The teleprinter remained in widespread use until the 1970's when electronic data processing and computer networking replaced many of its functions.

1904 British physicist John Ambrose Fleming invented the first practical diode or rectifier. Although first used in radio applications it became an important device for deriving direct current from the alternating current AC electricity distribution system, revitalising opportunities for DC powered devices, and indirectly, batteries. Fleming's invention of the thermionic valve (tube) could be said to be the beginning of modern electronics. Fleming also invented the potentiometer and the mnemonics known as Fleming's Right Hand Rule and Fleming's Left Hand Rule for remembering the three orthogonal directions associated with the force on the conductors, the electric current and the motion in electric generators and motors.

  • Ri(G)ht Hand Rule for (G)enerators. (F)irst (F)inger = magnetic (F)ield, se(C)ond finger = (C)urrent, thu(M)b = (M)otion.
  • The Left Hand Rule with the same mnemonic is used for motors since one of the factors is reversed.

1904 German engineer Christian Hülsmeyer invented and patented the first practical radar for detecting ships at sea which he called the Telemobiloscope. It consisted of a spark gap transmitter operating in the frequency range of 650 MHz, whose emissions were focused by a parabolic antenna located on the mast of the ship.  The receiving antenna picked up the reflected signals and when a ship was detected a bell was automatically rung. Using continuous wave transmissions, it was unable to measure distances. its range was limited to about one mile and at the time neither government nor private companies were interested in it.

1904 Patent granted to Harvey Hubbell in the USA for the "separable attachment-plug", the first 110 Volt AC mains plug and socket. Still in use today.

It is surprising that we had electric lights and motors, three phase power generation and distribution, cathode ray tubes, x-ray and electrocardiograph machines, alpha, beta and gamma rays, and batteries were over one hundred years old, all before the humble plug and socket were invented.

1904 Taking steam from the local volcanic hydrothermal springs, Prince Piero Ginori Conti tested the first geothermal power generator at the Larderello in Italy, using it to power four light bulbs. Seven years later, the world's first geothermal power plant was built on the same site.

1905 Annus Mirabilis - Einstein's miraculous year. In those twelve months, 25 year old patent clerk Albert Einstein, shook the foundations of classical physics with five great papers that established him as the world's leading physicist.

  • Einstein first challenged the wave theory of light, suggesting that light could also be regarded as a collection of particles, now called photons whose energy is proportional to the frequency (colour) of the radiation. A photon of electromagnetic energy is considered to be a discrete particle with zero mass and no electric charge and having an indefinitely long lifetime. This helped Plank's revolutionary quantum theory to gain acceptance. It was for this contribution to science that Einstein received the Nobel prize in 1921, not for the theory of relativity or E = mc2 as is popularly supposed. See also Hertz photoelectric effect(1887)
  • The second paper, Einstein's doctoral dissertation, shows how to calculate Avogadro's number and the size of molecules and surprisingly is Einstein's most cited work.
  • The third paper concerned the Brownian motion of small particles suspended in a liquid for which Einstein derived an equation for the mean free path of the particles as a function of the time. See also Brownian Motion (1827)
  • In the fourth paper, the first about relativity, Einstein showed that absolute time had to be replaced by a new absolute: the speed of light.
  • In his last paper that year Einstein asserted the equivalence of mass and energy E = mc2.

Einstein once said "The hardest thing in this world to understand are income taxes".

1905 The experimental findings of the German physical chemist Julius Tafel on the relationship between the internal potentials in a battery and the current flowing were summarised in Tafel's equation. It is a special case of the more theoretical Butler-Volmer equation (1930) which quantifies the electrochemical reactions in a battery.

1905 H. Piper in the USA patents the hybrid electric vehicle (HEV), a concept introduced in 1899 by Porsche in Germany and in Belgium by Pieper in 1900 and later demonstrated by Krieger in 1903 in France. A top speed of 25 mph was claimed.

1905 The Society of Automobile Engineers (SAE) was established in the USA to promote the professional interests of engineers and manufacturers in the fledgling automobile industry with 30 members headed by American engineer, Andrew Lawrence Riker as its first president and a young Henry Ford as vice president. Riker was the founder of The Riker Electric Vehicle Company producing his first electric car in 1894, using a pair of Remington bicycles as a base. In 1901, his electric-powered "Riker Torpedo" set a world speed record for electric cars that stood for ten years.

The role of the SAE was expanded in 1916, under the leadership of Elmer Sperry, to incorporate the management of the technical standards of American Society of Aeronautic Engineers, the Society of Tractor Engineers, as well as the interests of the power boating industry. Sperry coined the term "automotive" from the Greek, autos (self), and the Latin motivus (of motion), to describe any form of self powered vehicle and the SAE name was changed to the Society of Automotive Engineers to represent the interests of engineers in all types of mobility-related professions.

1905 French physicist Paul Langévin finally explained the cause of magnetism. He suggested that the alignment of molecular moments of the molecules in a paramagnetic substance were caused by an externally applied magnetic field and that the influence of the magnetic field on the alignment becomes progressively stronger with increasing temperature due to the thermal motion of the molecules. He also suggested that the magnetic moments of the molecule, the magnetic properties of a substance, are determined by the valence electrons. This notion subsequently influenced Niels Bohr in the construction of his classic model of the structure of the atom.

Langévin also pioneered the use of high intensity ultrasound for use in sonar applications.

1906 Canadian inventor and eccentric genius Reginald Aubrey Fessenden was the first to transmit and receive voices over radio waves, inventing the so called wireless which made broadcast radio possible. While Marconi's invention was equivalent to Morse's, Fessenden's invention was equivalent to Bell's. Bell superimposed a voice signal onto a DC current whereas Fessenden superimposed the voice signal onto a radio wave (a high frequency AC signal known as the carrier wave) varying the amplitude of the radio wave in a process known as amplitude modulation (AM radio). The term "modulation" was coined by Fessenden.

The radio wave which carried Fessenden's voice signal was provided by a multi-pole rotary radio frequency generator designed by Swedish born American immigrant working at General Electric, Ernst Frederik Werner Alexanderson. In fact a large input to the design came from Fessenden himself who also supervised the project. The generator had a large iron rotor into which were milled 360 teeth providing the magnetic poles rotating at 139 revolutions per second in a multi-pole stator. The output power was 300 Watts with a frequency of 50 kHz at 65 Volts. Promoted by G.E. it achieved fame as the "Alexanderson Generator" but it was not much of an advance on Tesla's 1890 design.

Demodulation, or detection, was by means of a diode device of Fessenden's own design which he called a Liquid Barretter. Similar to a crystal detector, this device rectified the signal, allowing only, either the negative going, or the positive going, cycles of the modulated radio wave to pass. When the output waveform was smoothed to separate the high frequency carrier wave, the result was a continuously varying signal representing the information in the original message. Up to that time, radio detectors such as coherers could only detect the presence or absence of a pulse and had to be reset after every pulse. They were suitable for telegraphy but not for voice transmission. Fessenden's system provided continuous detection of the varying amplitude of the radio wave thus enabling the transmission of voice messages or music.

Fessenden found it difficult to secure financial backing to develop his system. The concept of broadcasting was unknown or not appreciated at the time. Wireless communication was viewed simply as an alternative to the telephone system. The fact that unintended listeners could hear the message was seen as a drawback, not a benefit.

He also offered the rights to the patents which covered his radio broadcasting system to AT&T but they found it was was "admirably adapted to the transmission of news, music, etc." simultaneously to multiple locations, but they decided that it was not yet refined enough for commercial telephone service.

Fessenden was a prolific inventor, with over 500 patents relating to radio and sonar to his name including 5 for the heterodyne principle which made Armstrong rich and famous, but he never got the recognition he deserved. He was neither a good businessman nor an accomplished promoter and lost control of his patents and the possible wealth that flowed from them, dying a bitter and forgotten man.

See also Wireless Wonders.

1906 Patent awarded to American engineer Greenleaf Whittier Pickard working at AT&T for the crystal detector used to detect radio waves. Known as the cat's whisker it used the rectifying properties of the contact between a fine wire and certain metallic crystals, previously described by Braun, in what we would now call a point contact diode. The most common crystal used is naturally occurring lead sulphide, commonly called galena. Pickard also used Silicon Carbide (carborundum) crystals. The same year United States Army General Henry H.C. Dunwoody also patented a crystal detector device based on carborundum.

1907 Leo Hendrik Baekeland a Belgian immigrant in the USA investigating new materials for electrical insulation invented Bakelite, or "Oxybenzylmethylenglycolanhydride" to give it its Sunday name, the first thermosetting plastic which was later used to manufacture everything from telephone handsets to costume jewellery.

1907 American inventor Lee De Forest looking for ways to circumvent Fleming's patent on the diode valve discovered by chance that by adding a third electrode he could use it to control the current through the valve. He was able to use the device to amplify speech and he called it the audion tube (valve). It was the first active electronic device and it was very quickly adopted for use in radio circuits. Based on the success of the audion, de Forest laid claim to the title "The Father of Radio", ignoring the contributions of others.

Now called the triode it was first used as an amplifier but later used also as a switch.

1907 Henry Joseph Round an English radio engineer working for Marconi in New York, wrote to the "Electrical World" magazine with "A Note on Carborundum" describing his discovery that the crystal gave out a yellowish light when 10 Volts was applied between two points on its surface and that other crystals gave off green, orange or blue light when excited with voltages up to 110 Volts. He had inadvertently stumbled across the phenomenon on which the Light Emitting Diode (LED) depends, but there was not enough light to be useful and silicon carbide being hard to work with and Round's discovery was mostly forgotten. The phenomenon was rediscovered by Losev in 1922 and again by Holonyak in 1962.

1907 French physicist Pierre Ernst Weiss postulated the existence of an internal, "molecular" magnetic field in magnetic materials such as iron with molecules forming into microscopic regions he called magnetic domains within which the magnetic fields due to atoms are aligned. Under normal conditions domains themselves are randomly oriented and they have no magnetic effect. However, when they are put in a magnetic field, they tend to align themselves with the magnetic field causing the material to exhibit magnetic properties.

The concepts of paramagnetism and diamagnetism were first defined by Faraday in 1846. Magnetic properties are now understood to be a result of electric currents that are induced by the movement of the electrons in individual atoms and molecules. These currents, according to Ampere's law, produce magnetic moments in opposition to the applied field. The electron configuration in the atoms determines its magnetic properties whether diamagnetic or paramagnetic.

Diamagnetic materials, when placed in a magnetic field, have a magnetic moment induced in them that opposes the direction of the magnetic field. Paramagnetic behaviour results when the applied magnetic field lines up all the existing magnetic moments of the individual atoms or molecules that make up the material. This results in an overall magnetic moment that adds to the magnetic field. Pierre Curie showed that paramagnetism in nonmetallic substances is usually characterized by temperature dependence; that is, the size of an induced magnetic moment varies inversely to the temperature. Weiss's domains apply to ferromagnetic substances like iron which retains a magnetic moment even when the external magnetic field is removed. The strong magnetic effect causes the atoms or molecules to line up into domains. The energy expended in reorienting the domains from the magnetized back to the demagnetised state manifests itself in a lag in response, known as hysteresis. Ferromagnetic materials lose their magnetic properties when heated, the loss becoming complete above the Curie temperature.

1907 After almost 3000 years of use in various forms, the first patent for the process of silk screen printing or serigraphy (from the Latin "Seri" - silk) was awarded to English printer Samuel Simon of Manchester. Although the use of a rubber bladed squeegee to force the ink through the stencil was already known, he is generally credited with the idea of using silk fabric as a screen or ground to hold a tieless stencil. Screen printing derives from the ancient art of stenciling used by the Egyptians as early as 2500 B.C. and refined by the Chinese in the seventh century A.D.. Screen printing is arguably the most versatile of all printing processes, able to print on any surface, with any shape or contour and any size. Although the silk mesh has been replaced by more durable or stable materials such as polyester and perforated metal screens, the technique is still used extensively in the electronics industry today for printing thick film and thin film circuits, for printing the etching patterns for printed circuit board tracks and for the precision application of conductive and other adhesives for making connections and mounting components on surface mounted printed circuit boards as well as for the conventional printing of logos, designs and text on both components and packaging.

1907 French engineer Paul Héroult, developed the first commercial electric arc furnaces for steel making. The first plant was installed in the USA and was designed for batch processing scrap metal. The furnace charge of scrap iron is heated by very large electric currents passing between graphite electrodes in contact with the metal. Oxygen is also blown into the melt burning out impurities such as silicon, sulphur, phosphorus, aluminium, manganese and calcium which are converted to slag which can be removed. The operation is a batch process but very fast turn-arounds are possible. It can also be very precisely controlled and started and stopped very quickly if necessary, something which is not possible with blast furnaces. Electric arc furnaces are also cheaper to build and more efficient than conventional blast furnaces.

See also Iron and Steel Making

1908 Construction of the first Germanpumped storage power plant and of hydraulic research centre in Brunnenmuehle in Heidenheim by Voith Turbo. Since then many more pumped storage systems have been installed throughout the world. The hydraulic battery.

1908 Swiss textile engineer Jacques Edwin Brandenberger invented Cellophane, made from the cellulose fibres of wood or cotton. It is used as a separator in batteries particularly in silver oxide cells.

1909 Danish biochemist Søren Peter Lauritz Sørensen introduced the concept of pH as a measure of the acidity or alkalinity of a solution.

1909 Hermetically sealed wet battery introduced by Beautey in France.

1910 American Robert Millikan determined the charge on the electron by means of his Oil Drop experiment.

In 1897 John S.E. Townsend one of J.J. Thomson's research students, and in 1903 Thomson himself with H.A. Wilson (no relation to the inventor of the "Cloud Chamber"), had measured the charge on the electron with a similar method using a water cloud but their results were inaccurate. Millikan adapted this technique with some ingenious (and some not so ingenious) changes to measure e to within a 0.4% accuracy. A fine mist of oil drops was introduced into a chamber in which the air was ionised by X-rays. From the ionised gas some electrons attach themselves to some of the oil droplets. At the top of the chamber was a positively charged plate with a corresponding negative plate at the base. Charged droplets (with electrons) were attracted upwards to the positive plate while uncharged droplets fell downwards under the influence of gravity. By adjusting the voltage between the plates the electrical field could be varied to increase or decrease the upward force on the charged droplets. The voltage was adjusted so that the charged particles appeared stationary at which point the electrostatic force just balanced the gravitational force. The charge on the electron could then be calculated from a knowledge of the electrical field and the mass of the oil droplet determined by the speed at which it falls. Since the magnitude of the e/m ratio had already been determined by J.J. Thomson, the experiment also allowed the mass of the electron to be determined. From his work we know that the electron has a charge of -1.6 X 10-19 Coulombs and a mass of 9.1 X 10-31 Kg, which is only 0.0005 the mass of a proton. From this we can derive that a current of 1 Amp (1 Coulomb per second) is equivalent to an electron flow of 6.3 X 1018 electrons per second.

Although Millikan's method was beautifully simple, his published conclusions did not truly reflect the results of the measurements made. He was selective in choosing the results, discarding two thirds of the measurements made because they did not support his conclusions, at the same time improving the accuracy of the experiment. He was right, but it took others to prove it conclusively.

Millikan initially studied classics and worked as a teacher and administrator. He did not begin to do research seriously until he was almost forty. He eventually was awarded the Nobel prize for his determination of Planck's Constant.

1910 German physicist and Jesuit priest, Theodor Wulf, measured background radiation at different altitudes with an ionising electrometer of his own design taking measurements on the ground and at various levels up the Eiffel tower. He expected that the radiation would be emanating from the earth and that the level would decrease with altitude. He found that indeed the level ionisation of the air caused by radiation did reduce with altitude but not as much as he expected. At the top of the tower (330 metres) it was about half what it was at ground level whereas he expected it to halve in only 80 metres. He concluded that the anomaly was due to some form of extra-terrestrial energy entering the earth's atmosphere.

Wulf published his results in Physikalische Zeitschrift but they were initially not accepted by his peers, however two years later, his experiment was repeated at higher altitudes by Austrian-American physicist, Victor Francis Hess who took improved electrometers up to 5300 metres in a hot air balloon. He confirmed that, at that altitude, the ionisation of the air increased to four times the ground level ionisation and that the radiation causing it was coming from outside of the earth's atmosphere.

The term "cosmic rays" was subsequently coined by Robert Millikan and Hess, not Wulf, was credited with their discovery for which he was awarded the Nobel in 1936.

See more about Cosmic Rays

1910 William David Coolidge working at General Electric in the USA invented the tungsten filament which greatly improved the longevity of the light bulb.

1910 Neon lighting using the techniques discovered by Plücker and Hittorf and the newly discovered neon gas was patented by French experimenter Georges Claude. Substituting different gases allowed a range of colours to be produced. Although the neon lights were used for advertising in France it was not until 1923 that they were brought to the USA by Packard car dealer Earl Anthony.

1911 Dutch physicist Heike Kamerlingh Onnes of Leiden University is generally credited with the discovery of superconductivity. In fact Kamerlingh Onnes subsequent Nobel award was in recognition of his liquefaction of Helium, not for the discovery of superconductivity. It was his assistant Gilles Holst who first observed that the electrical resistance of Mercury suddenly disappeared when it was cooled to 4 degrees Kelvin, the temperature of liquid Helium. Sadly, the contribution of Holst is long forgotten.

1911 The experiment on radioactivity that contributed most to our knowledge of the structure of the atom was done by Rutherford, who with Soddy had previously identified the atomic radiation emitted by Uranium and explained the phenomenon of radioactive transformation. Working at the University of Manchester with his students Hans Geiger (later famous for his "Counter") and Ernset Marsden, Rutherford bombarded a thin foil of gold with a beam of alpha particles (Helium nuclei) and looked at the beams on a fluorescent screen. They noticed that most of the particles went straight through the foil and struck the screen but some (0.1 percent) were deflected or scattered in front (at various angles) of the foil, while others were scattered behind the foil.

Rutherford concluded that the gold atoms were mostly empty space which allowed most of the alpha particles through. However, some small region of the atom must have been dense enough to deflect or scatter the alpha particle. He called this dense region which comprised most of the mass of the atom the atomic nucleus and proposed the model of an atom with a nucleus and orbiting electrons.

Awarded a Nobel prize for his work on the structure of the atom, he famously said "The energy produced by the breaking down of the atom is a very poor kind of thing. Anyone who expects a source of power from the transformation of these atoms is talking moonshine. " If he didn't believe Einstein, he could have at least profited from advice from another of his students, Niels Bohr (1913 below).

1911 In an address to the Röntgen Society, Scottish engineer Alan Archibald (A.A.) Campbell Swinton described in detail the workings of a proposed all electronic television system using a cathode ray tube scanning an array of photocells onto which the image was projected for the transmitter and another cathode ray tube scanning a fluorescent screen as the receiver. This was at a time when the possibilities of radio communication had just been discovered, radio valves were practically unknown, photocells were most inefficient and vacuum technology was still very primitive. Due to obvious difficulties at the time the system was never constructed. It was left to another Scottish inventor, John Logie Baird to demonstrate the first working television system in 1926. It was an electromechanical system based on the Nipkow disc image scanning system. Although Baird's system was used in 1929 for the first public broadcasts in the UK, electromechanical systems proved to be a dead end.

1912 J J Thomson and Frederick Soddy discovered isotopes by observing the different parabolic paths traced by ions of different mass when passing through electric and magnetic fields. Soddy formulated the concept of isotopes, for which he was awarded a Nobel Prize in 1921. It states that certain elements exist in two or more forms which have different atomic weights but which are indistinguishable chemically. They used this phenomenon to construct the first Mass Spectrometer (then called a parabola spectrograph), a tool that allows the determination of the mass-to-charge ratio of ions and the identification of the different compounds contained in chemical samples. The Mass Spectrometer has since become an ubiquitous research tool in chemistry.

1912 Various alloys of Stainless Steel were independently developed by inventors working in three different companies.

Similar corrosion resistant steels had been investigated in the past by British Robert A. Hadfield in 1892, and later by L. Guillet and A. M. Portevin in France and W. Giesen in England and in 1913 by Philip Monnartz in Germany who had all reported on the relationship between the chromium content and corrosion resistance, however none of the results of these investigations were converted into commercial products. The newly developed alloys from 1912 enabled the mass production of stainless steel.

  • American metallurgist and automotive engineer, Elwood P. Haynes, mixed tungsten with chromium and steel to produce strong lightweight corrosion free alloys which could withstand very high temperatures. He had been working for several years on stainless steel alloys but did not apply for a US patent for his martensitic stainless steel alloy until 1915. ("Martensitic" describes the property of the crystal structure of the steel alloy, in this case a tetragonal, body centred, crystal lattice.) Martensitic steel is brittle with poor toughness, but hardness and toughness can be improved significantly by tempering. It is also magnetic.
  • Haynes' patent was not granted until 1919.

    Haynes also designed and produced one of America's first automobiles, the Pioneer in 1894.

  • British metallurgist Harry Brearley working at Firth-Brown in Sheffield, where he had started his employment as a labourer, was searching for high temperature steels which could better resist the erosion or wear of gun barrels caused by the high temperature discharge gases. Experimenting by alloying the steel with different amounts of chromium which was known to produce steel with a higher melting point, in 1913 he produced a martensitic steel containing 0.24% by weight of carbon and 12.85% of chromium which was the first true stainless steel. To examine the grain structure of the steel under a microscope he used acidic etching reagents such as nitric acid to prepare the sample surfaces. He noticed that these samples were also resistant to chemical corrosion and followed up by exposing the samples to common acids such as those found in foods including vinegar (acetic acid) and lemon juice (citric acid). At the time Sheffield was the centre of the UK's cutlery manufacturing industry and Brierley saw the opportunity to produce better rust free knives. Failing to persuade Firth-Brown of this opportunity, he commissioned a local cutler to manufacture his own knives using this new steel. He was thus the first to commercialise stainless steel.
  • Brearley announced his product in the USA in 1915 and applied for a US patent there the same year only to find that Haynes had already registered a patent just a few days before.

    Haynes and Brierley eventually joined forces to jointly commercialise their invention.

  • At the same time, engineers at Krupp in Germany, Benno Strauss and Eduard Maurer patented austenitic stainless steel. (Austenitic steel has a face centred, hexagonal crystal lattice.) They added nickel to the melt to produce a non-magnetic steel which was more resistant to acids, was softer and more ductile and therefore easier to work than Haynes' and Brierley's martensitic steel. Austenitic steels contain a maximum of 0.15% by weight of carbon, a minimum of 16% chromium and sufficient nickel and/or lower cost manganese to maintain the austenitic structure over a wide temperature range.
  • Over 70% of modern stainless steel production is austenitic steel.

Subsequently many more variants of stainless steel have been developed with properties optimised for specific applications.

See also Iron and Steel Making

1912 Charles Kettering in the USA invented the first practical self-starter for automobiles, originally patented by Dowsing in 1896. The subsequent adoption by General Motors of battery-started cars provided the impetus for massive growth in the demand for lead acid batteries spawning new developments and performance improvements. See Willard 1915.

1912 Australian born Sir William Lawrence Bragg working with his father British physicist William Henry Bragg at Cambridge University discovered X-ray diffraction and formulated Bragg Law to quantify the phenomenon, thus founding the study of X-ray crystallography. The process is used to analyse crystal structure by studying the characteristic patterns of X-rays that deviate from their original paths because of deflection by the closely spaced atoms in the crystal. This technique is one of the most widely used structural analysis techniques and plays a major role in fields as diverse as structural biology and materials science. X-ray crystallography is used in battery design to analyse alternative chemical mixes and the associated crystal structures to optimise the physical and chemical characteristics of the active chemical contents in the cells. The ability to study the structure of crystals marked the origin of solid-state physics and provided a vital tool for the development of today's semiconductor industry.

1912 German physicist Max von Laue proved that X-rays are electromagnetic waves with a wavelength shorter than or of the same order as the separations between the ordered atoms in a crystal by examining the interference or diffraction effects that could be observed when an X-ray beam hits layers of atoms in a crystal. The wavelength observed was about 1000 times shorter than the wavelength of light. Von Laue was given the 1914 Nobel Prize for his discovery of diffraction of X-rays

1912 Scottish physicist Charles Thomson Rees Wilson devised the Wilson cloud chamber as a means of making the tracks of ionising radiation visible in order to detect sub atomic particles such as protons and electrons and other ionising radiation. It consisted of a closed container filled with a supersaturated vapour such as water in air. When ionising radiation passes through the vapour, it leaves a trail of charged particles (ions) that serve as condensation centres for the vapour which condenses around them. The path of the radiation is thus indicated by tracks of tiny liquid droplets in the supersaturated vapour.

1912 Twenty one year old Russian immigrant David Sarnoff was working as a telegraph operator at the Marconi Wireless station in New York when SOS signals from the sinking S.S. Titanic came in from the frozen North Atlantic. Staying at his post relaying messages for 72 hours straight brought him instant fame. The experience convinced him of the potential of radio and he went on to found the Radio Corporation of America RCA.

1912 American college student Edwin Howard Armstrong invented the regenerative or "feedback" radio receiver which he subsequently patented in 1914. By using positive feedback he dramatically increased the gain of the valve amplifiers used in radio circuits improving their sensitivity. Lee De Forest subsequently claimed credit for this invention because it used his audion valve. See also Frequency Modulation.

1912 Deaf American Henrietta Swan Leavitt, hired by Harvard College Observatory to catalogue the brightness of stars in a system known as the Magellanic Clouds from thousands of glass photographic plates, noticed that the changing brightness of Cepheid Variable stars was related to the length of their periodic cycles of variation, (typically between 1 and 50 days). Since all the stars in the Magellanic Clouds are approximately at the same distance from the Earth, she deduced that their relative brightness can be directly compared. She published her conclusion that the intrinsic brightness of Cepheid stars is directly proportional to the time to complete a full pulsation cycle of their brightness, known as the period-luminosity relation. Thus, once the period is known, the brightness can be inferred. Bright objects of a known luminosity such as the Magellanic Cloud Cepheids are called standard candles.

The first pulsating star was discovered in 1784 by English astronomer Edward Pigott who detected the variability of a star Eta Aquilae however it was the discovery a few months later of a second pulsating star Delta Cephei, by Dutch born, profoundly deaf, amateur astronomer living in England, John Goodricke, which gave its name to a new class of variable stars. The variation in brightness of Cepheid stars occurs as the supply of Hydrogen fuelling the star's energy creation diminishes creating an imbalance between the inward gravitational pressure and the outward pressure, due to the nuclear fusion reactions, causing the star to expand and contract.

Leavitt died of cancer at the age of 53 before the far reaching implications of her discovery on our understanding of the universe were realised by Harlow Shapley and Edwin Hubble and she was not recognised in her lifetime.

1913 Neils Bohr a Danish physicist working under Rutherford in Manchester applied quantum theory to molecular structure proposing a more detailed model of the atom with electrons existing in orbits that had discrete quantised energies, or specific energy levels. He proposed that the chemical properties of the element are largely determined by the number of electrons in the outer orbits and introduced the idea that an electron could drop from a higher-energy orbit to a lower one, emitting a photon (light quantum) of discrete energy. This became the basis for quantum mechanics for which he was awarded a Nobel prize in 1922.

In contrast to his mentor Rutherford, Bohr is quoted as saying "Prediction is very difficult, especially about the future"

1913 Young English Physicist Henry Gwyn Jeffreys Moseley working with Rutherford at Manchester explained for the first time the fundamental pattern underlying the periodic table. Using X-ray spectra obtained by diffraction in crystals bombarded with cathode rays, he found that the heavier the atomic mass of the element, the shorter was the wavelength and the more penetrating were the X-rays emitted, indicating a systematic relationship between the wavelength of the X-rays and the atomic mass of the element. (X-rays are generated when a focused electron beam accelerated across a high voltage field bombards a stationary or rotating solid target). He determined that the positive charge on the nuclei of the atoms always increases by 1 in passing from one element to the next in the periodic table and he called this the atomic number. Moseley's discovery showed that atomic numbers were not arbitrary as had previously been thought, but followed an experimentally verifiable pattern. He predicted the existence of two new elements, now known to be radioactive, non-naturally-occurring technetium and promethium, by showing that there were gaps in the sequence at numbers 43 and 61.

Like many other patriotic youths at the time Moseley volunteered to serve in the First World War and was killed at Galipoli at the age of 27.

1913 Patent filed by Arthur Berry for etched printed circuits used in heaters. Similar subtractive techniques were also proposed by Littlefield and E. Bassist using photoengraving and electrodeposition of copper but the ideas do not appear to have caught on.

1913 Henry Ford introduced the moving conveyor line for assembly operations. Also called the paced production line, in conjunction with better materials flow to each work place, it enforced work rate and line discipline enabling major efficiency gains to be achieved. It was not popular but the huge reductions in assembly time enabled Ford to pay higher wages. Paced production lines are now the norm for producing high volumes of high labour content products.

1914 Using the photoelectric effect Millikan determined Plank's constant directly - verifying the 1905 Einstein theory of the photoelectric effect and the quantum nature of light. (After ten years trying to prove Einstein's photon or particle theory that light was wrong, he eventually succeeded in proving it was right.) He was awarded the Noble prize for this work in 1923.

1914 American astronomer Vesto Melvin Slipher at the Lowell Observatory in Arizona presented the initial results of his studies of the red shift of light spectra from distant galaxies to the American Astronomical Society showing that out of 15 galaxies, 11 were clearly red-shifted. Taking into account the Doppler effect, this was the first indication of the expanding universe.

1915 American physicist Manson Benedicks discovers the rectifying properties of germanium crystals, a discovery that will ultimately lead to the development of the "semiconductor chip".

1915 Improvements to automotive lead acid SLI battery reliability and safety introduced by Willard Storage Battery Company including rubber plate separators and shortly afterwards hard rubber cases. Previously lead acid battery designs had been diverse and unreliable with cases and separators constructed from a variety of materials such as wood dipped in asphalt, waxed leather, ceramics and glass. For the next 30 years or more, until the availability of easily moulded plastics, the construction of automotive batteries was based on design concepts introduced by Willard.

1915 During the First World War, batteries became essential for powering torches and particularly military field telegraph equipment but the source of pyrolusite from which is derived the manganese dioxide, needed for Leclanché cells, was controlled by the Germans and an alternative had to be found. In response, French physicist Charles Fery developed an alternative air depolarising battery. The cathode was a large porous carbon pot, only partially filled by the zinc anode and the electrolyte was open to the air. The design essentially diluted the polarisation effect of the hydrogen generated and promoted contact with the oxygen in the air for recombination into water. It was not very efficient but although it was not perfect it served its purpose and 1.5 million were produced. It could be considered the forerunner of the Zinc-Air battery.

1915 Western Electric engineer Edwin H. Colpitts patented the push-pull amplifier. The design used a phase splitter to separate the positive going part of the wave form from the negative going part and amplified the two parts in separate valves (tubes). After amplification the two parts were recombined to reconstitute the waveform. Since two valves were used the design permitted higher power outputs to be achieved and at the same time, because the voltage swing in each valve was lower, the circuit provided linear amplification free from distortion.

1915 American engineer Ralph Vinton Lyon Hartley working at Western Electric invents the variable frequency Hartley oscillator which can be tuned using a variable capacitor. Oscillation is induced by positive feedback around a valve (tube) amplifier. The frequency of oscillation is determined by two inductors (or a tapped single inductor) and a single capacitor. Modern versions use transistors or operational amplifiers to provide the amplification.

The same year fellow Western Electric engineer E. H. Colpitts (see above) invented an alternative oscillator with slightly better frequency stability. It is the electrical dual of a Hartley oscillator using two capacitors and one inductor determine the frequency.

1915 A busy year for Western Electric, another of their engineers, American John Renshaw Carson published a mathematical analysis of the modulation and demodulation process and filed a patent for single-sideband and suppressed carrier amplitude modulation techniques which was eventually granted in 1923. His theory paved the way for the development of frequency division multiplexing

1915 American astronomer Harlow Shapley working at the Mt Wilson Observatory realised that Leavitt's period-luminosity relation could be used to estimate the distance between different galaxies by comparing the relative brightness of their Cepheids and using the inverse square law to calculate the distance between them. This provided a method of estimating the distance to far off galaxies by comparing the brightness of the Cepheids in the distant galaxy with the brightness of Cepheids in the Magellanic Clouds.

To provide absolute cosmic distances however he needed a reference and this was provided by Danish astronomer Ejnar Hertzsprung who in 1913 pioneered a statistical method to calibrate the distance to the Magellanic Cloud.

1916 American chemist Gilbert Newton Lewis advanced Frankland's theory of valency and established the basis of the theory of chemical bonding by proposing that chemical bonds are formed between the atoms in a compound because electrons from the atoms interact with each other. He had observed that many elements are most stable when they contained eight electrons in their valence shell and suggested that atoms with fewer than eight valence electrons bond together to share electrons and complete their valence shells.

The compounds used in batteries consist mainly of metal and non-metal atoms held together by ionic bonding in which electrons are completely transferred from one atom to another. The atoms losing a negatively charged electrons form positively charged ions, while the atoms gaining electrons become negatively charged ions. The oppositely charged ions are attracted to each other by electrostatic forces which are the basis of the ionic bond. This explains the theory of dissociation proposed by Arrhenius in 1884.

1916 German physicist Arnold Johannes Wilhelm Sommerfeld enhanced the Bohr theory of the atomic structure by introducing non-circular orbits, by allowing quantised orientations of the orbits in space, and by taking into account the relativistic variation in the mass of the electron as it orbited the nucleus at high speed. These properties or quantum states were characterised by three quantum numbers in what is now called the Bohr-Sommerfeld model of the atom.

1916 During military service as an officer of the Tsarist army fighting on Germany's Eastern Front during the World War I, Russian engineer and mathematician Aleksandr Ignatyevich Shargei from Kiev, (now part of Ukraine), filled four notebooks with his ideas about interplanetary flight. After the war and the 1917 Russian revolution he was at high risk of arrest by the Bolshevik authorities as an enemy of the people, so he adopted the identity of a dead man, Yuri Vasilievich Kondratyuk, and in 1925, he self published his ideas in a book, The Conquest of Interplanetary Space under Kondratyuk's name. In the book he outlined the concept of Lunar Orbit Rendezvous (LOR) using a modular spacecraft consisting of a propulsion unit carrying a small landing craft to reach and orbit the Moon. The propulsion unit would remain in orbit around the Moon while the smaller landing craft journeyed to the surface and back to the propulsion unit which would then return to Earth leaving the landing craft behind. This strategy was eventually proposed by John C Houbolt for the Apollo Moon Mission.

Kondratyuk also suggested using a gravitational slingshot trajectory to accelerate a spacecraft and he included detailed calculations of the trajectory to take a spacecraft from Earth orbit to lunar orbit and back to Earth orbit, a trajectory now known as "Kondratyuk's Loop" or more commonly the Free Return Trajectory. See Apollo Trans Lunar Injection.

In 1932 Kondratyuk had the opportunity to meet Sergei Korolev, then head of the GIRD (Soviet Rocket Research Group). Korolev offered Kondratyuk a position on his staff, but he declined, fearing that the scrutiny he would come under by the NKVD (Russian Secret Police) would reveal his true identity.

1916 1916 Edwin Fitch Northrup working at Princeton University invents the coreless high frequency induction furnace.

1916 Metallurgist Jan Czochralski, born in Kcynia, Western Poland, then part of Prussia (Germany), working in Berlin accidentally discovered a method of drawing single crystals when when he absent mindedly dipped his pen into a crucible of molten tin rather than his inkwell. On pulling the pen out he discovered that a thin thread of solidified metal was hanging from the nib. Experimenting with a capillary in place of the nib, he verified that the crystallized metal was a single crystal and went on to develop the technology for producing large single crystals, still a fundamental process for semiconductor fabrication today.

At the request of the president of Poland, in 1928 he moved back to Poland to take up the post of Professor of Metallurgy and Metal Research at the Chemistry Department of the Warsaw University of Technology where he published many papers. However after World War II he was unjustly accused of aiding the Germans during the war and stripped of his professorship. Although he was later cleared of any wrongdoing by a Polish court, he returned to his native town of Kcynia where he ran a small cosmetics and household chemicals firm until his death in 1953.

The Czochralski (CZ) method of growing single crystals was adopted in 1950 by Bell Labs and is used today in 95% of all semiconductor production.

1917 American engineer George Ashley Campbell awarded patents for low pass, high pass and band pass filters consisting capacitors and inductors. These passive electric wave filters had already been employed for several years in the telecommunications industry for signal conditioning, selection and tuning and similar designs had been developed in Germany by K W Wagner in 1915.

1917 Rutherford bombarded Nitrogen gas with naturally occurring alpha particles (Helium nuclei) from radioactive material and obtained atoms of an Oxygen isotope and positively charged particles with a higher energy which he called protons (Hydrogen nuclei, isolated for the first time). He had split the atom, creating the world's first nuclear reaction, albeit a weak one. Rutherford had achieved the alchemist's dream of transmuting matter, which led to the work on nuclear fission.

Rutherford did not publish the results of this experiment until two years later in 1919. He continued his investigations with Cockcroft and Walton who started work in 1928 on a controlled source of high energy particles which enabled them probe deeper into the atomic structure.

1918 Edwin Howard Armstrong patented the superheterodyne radio receiver solving the problem of providing a wide tuning range and high selectivity between stations. This was achieved by using a variable frequency local oscillator or frequency changer to shift the frequency of the signal (carrier wave plus sidebands) from the desired transmitter to a convenient fixed intermediate frequency (IF). Tuning and amplification take place in a separate narrow band IF amplifier which only needs to be tuned to a single frequency simplifying the design considerably as well as improving performance (selectivity).

German engineer Walter Schottky also independently invented a superheterodyne radio receiver the same year.

A simple version of the idea had been used by Fessenden in 1901 but he had not developed it. He did however give the circuit its name from the Greek heteros (other) and dynamis (force). Until the digital age and phase locked loops, the superheterodyne principle was used in 98% of all radios world wide.

1918 Max Schoop produced high current printed circuit boards with heavy tracks for high power vacuum tube circuits using metal deposition by flame spraying through a mask. While successful, like Berry's ideas before him, they were not taken up by others.

1919 The flip-flop or bi-stable latch circuit a basic building block in all digital computers and logic circuits was invented by British engineers William Henry Eccles and F.W. Jordan working at the government's National Physical Laboratory. Originally implemented with triodes, now with transistors (diagram), it can remember two possible conditions or states and thus is able to store a single bit of information or a binary digit, thus enabling computers to count. This was the circuit chosen in 1958 by Robert Noyce for the first planar Integrated Circuit.

Eccles and Jordan were not Americans as reported on many US based web sites. Another internet myth. Eccles did pioneering work on radio propagation and was a Fellow of the Royal Society (FRS). He rose to be President of the Physical Society from 1928 to 1930, and President of the Institute of Electrical Engineers (IEE) in 1926. Jordan faded into obscurity.

1919 The Electret, the electrostatic equivalent of the permanent magnet, was discovered by Mototaro Eguchi in Japan. Electrets are dielectric materials that have been permanently electrically charged or polarised. They are produced by heating certain dielectric materials to a high temperature and then letting them cool while immersed in a strong electric field. The materials are composed of long molecule chains, each with an electric dipole moment which can be formed into electrostatic domains similar to the magnetic domains found in magnets. Electret foils are commonly used in microphone transducers since they do not require a polarising voltage to be applied as in "condenser" microphones.

1919 The tetrode valve was invented by Walter Schottky who discovered that by placing a grid between the anode plate and the control grid of a triode valve, the grid-plate capacitance was reduced to almost one-hundredth of that in the triode. The second grid acted as a screen to prevent the anode voltages from affecting the control grid and eliminated instability (oscillation) caused by anode-grid feedback in the triode valve.

1919 American mechanical engineer and patent lawyer Elliott J. Stoddard patented an "air" engine similar to the Stirling engine. It used two large heat exchangers for the heat source and sink and a valve arrangement to shorten the flow of the working fluid to eliminate dead space and hence improve efficiency. Later versions used alternative working gases such as Helium and Hydrogen.

1919 Alexander McLean Nicholson working at Bell Labs (then Western Electric) on growing Rochelle-salt piezoelectric crystals for use in loudspeakers, microphones and oscillator circuits, filed patents on his work, but the only development leading to commercially successful telephone technology products was the crystal oscillator.

When a varying signal is applied across a piezoelectric crystal it expands and contracts in sympathy. The crystal oscillator circuit sustains oscillation by taking a voltage signal from the crystal, amplifying it, and feeding it back to the crystal which resonates at a certain frequency determined by its cut and size.

Independent of Nicholson and working contemporaneously with him on circuits using piezoelectric crystals was academic W.G. Cady and though they both applied for patents, after litigation, judgement was given in favour of Nicholson, backed by Bell Labs, as the originator of the crystal oscillator.

Today more than 2,000,000,000 quartz crystals are produced annually for use in electronic circuits needing precise frequency control including radio tuners, mobile phones, computers, clocks and watches.

1920 The first regular commercial radio broadcasts by KDKA in Pittsburgh. By the end of 1922 a further 563 licensed A.M. radio stations are operating.

1920 Cambridge scientist Francis William Aston investigating atomic masses using a mass spectrometer discovered that four Hydrogen nuclei (4 protons) were heavier than a Helium nucleus which has the same number of nucleons (2 protons and 2 neutrons). British astrophysicist Arthur Eddington recognised that this mass difference could represent the equivalent amount of energy released when Hydrogen atoms and neutrons were fused together into a Helium atom as predicted by Einstein's equation, E=Mc2, and that this could explain the source of the Sun's energy. In 1939 Hans Bethe explained in detail how this may come about.

Meanwhile Aston continued his spectrographic studies of more elements and plotted a chart of the differences between their atomic mass and the mass of their constituent protons and neutrons. Elements at the ends of the periodic table (Hydrogen and Uranium) had high mass differences reducing towards a minimum for elements near the middle if the table (Iron and Nickel). The mass difference is now called the mass defect and it corresponds to the binding energy associated with the element. This is equivalent to the energy needed to separate an element into its constituent nucleons. Aston's chart of mass differences is the mirror image, about the horizontal axis, of the chart of the binding energy of the elements.

Aston won the Nobel Prize for Chemistry in 1922.

1920 Exploring ways to circumvent De Forrest's patents on the triode amplifier or audion tube, American electrical engineer Albert W. Hull, working at General Electric Research Labs, invented the Magnetron.

Attempting to control the anode current by using a varying magnetic field, rather than by electrostatic means he constructed a vacuum tube containing an anode in the form of a cylindrical tube and a rod shaped cathode contained within the tube an on its centre line. Magnets at each end of the cylinder were used to provide an axial magnetic field along the length of the electrodes. See diagram of Hull's Magnetron. Electrons emitted by the cathode would be attracted directly towards the anode by the radial electric field between the two electrodes but would actually follow a curved path outwards towards the anode due to the influence of the magnetic field. At low magnetic field strengths the curved path of the electrons across the gap between the cathode and the anode would have a large radius. As the field strength was increased the current would remain constant but the radius of the curve would reduce until it reached a critical point beyond which the electrons would not reach the anode but would instead curve back to the cathode resulting in the current being suddenly cut off.

The device was thus not successful as an amplifier but it did find use as a low power oscillator taking advantage of the instability caused around the point of critical magnetic field strength and the resonant properties of the electrode structure. In 1924 however Czech physicist August Zácek and German physicist Erich Habann independently discovered that the magnetron could generate radio waves of 100 megahertz to 1 gigahertz.

See also the Cavity Magnetron.

1921 12% of British homes wired for electricity

1921 American physicist and engineer Walter Guyton Cady working at Wesleyan University in Middletown, Connecticut submitted a paper to the Proceedings of the Institute of Radio Engineers describing for the first time, the principles of the crystal controlled oscillator circuit. He foresaw their use as frequency standards and filed two fundamental patents in 1920 and 1921.

Radio transmission and reception equipment depend on highly stable, precision oscillators. Before that time, an electronic oscillator used a valve (vacuum tube) amplifier with a tuned (resonant) circuit, consisting of capacitors and inductors, in a positive feedback loop to sustain and control the frequency of oscillation. Cady's circuit made use of the mechanical resonance properties of piezo-electric crystals. It used three valves and a four terminal piezo-electric crystal resonator in the feedback loop eliminating the capacitors and inductors and and achieved a stability 100 times better than conventional resonant circuits.

In 1923 Cady shared his thoughts with, Harvard professor G. W. Pierce, who contacted his patent lawyer and immediately set to work to improve on Cady's design.

Cady also lost out to Bell Labs researcher A.M. Nicholson whose patent for a crystal oscillator was given priority.

1921 American inventor Thomas Midgley working at General Motors (GM) discovered a fuel additive tetraethyl lead which prevented pre-ignition, known as knocking, in internal combustion engines solving a major problem in the automobile industry. It was launched the following year and quickly adopted by petrol (gasoline) companies worldwide who switched to leaded fuel. Unfortunately lead in certain forms is toxic and for sixty years, almost unchallenged, it polluted the atmosphere, killing or disabling many in the industry who had too close a contact with it, until consumer pressure forced the automakers to begin producing cars that ran on lead free fuel.

It is said that Midgley himself suffered from the effects of lead poisoning.

In 1928 GM assigned Midgley a new task, to find a safe alternative to the toxic refrigerants used in refrigerators and air conditioners. (See Refrigerators) He came up with a range of colourless, odourless, nonflammable, noncorrosive gases or liquids known as chlorofluorocarbons (CFCs) with boiling points suitable for vapour compression refrigerators and personally demonstrated the benign properties of these wonderful new gases by inhaling a lung-full and exhaling it onto a candle flame which was extinguished. Decades, and untold millions of refrigerators, later it was discovered that CFCs were destroying the ozone layer and jeopardising the ecosystems of the planet.

Never in the history of mankind had so much damage been done to the atmosphere by one man with the best of intentions.

The unfortunate Mr. Midgley was eventually killed at the age of 51 by another of his own helpful inventions. Suffering from polio he lost the use of his legs. To get himself out of bed he invented a harness but one day he accidentally tangled in his contraption which strangled him.

1920's Diesel electric locomotives first introduced with electric drives providing the transmission mechanism eliminating the need for a clutch and a gearbox. (Electric drives provide maximum torque at zero speed. Internal combustion engines can only provide driving torque when they are running at speed)

1922 The BBC was formed in the UK by a group of leading "wireless" manufacturers including Marconi and started a radio broadcast service. Widespread radio broadcasting started around the same time in many countries throughout the world bringing wireless into the heart of many homes and with it a new demand for batteries to power them.

1922 Light emission from silicon carbide diodes was rediscovered in the Soviet Union by self taught Oleg V. Losev. He produced a range of high frequency oscillating, amplifying and detector diodes using zinc oxide and silicon carbide crystals about which he published 16 papers on the underlying theory of operation and was awarded ten patents on Light Emitting Diodes (LED)'s, photodiodes and optical decoders of high frequency signals.

Even more amazing was his discovery of the negative resistance (dI/dV) characteristic that can be obtained from biased point-contact zincite (ZnO) crystal diodes and the possibility of using this negative resistance region to obtain amplification, anticipating the tunnel diode. See negative resistance characteristic. He used these properties to construct fully solid-state RF amplifiers, detectors and oscillators at frequencies up to 5MHz a quarter century before the invention of the transistor.

He designed and constructed over 50 radio receivers, incorporating his own tuning, heterodyning and frequency converting circuits and built a production line to produce his cristadyne radio receivers, powered by 12 Volt batteries, thirty years before the transistor radio. Inter-stage interaction inherent in using two-terminal devices to obtain gain and adjusting the cat's whiskers were problematical but the radios worked. These problems together with the difficulties of obtaining zincite which was found in commercially significant quantities in only two mines, both in New Jersey, USA led to Losev eventually abandoning the cristadyne.

Losev starved to death during the siege of Leningrad in 1942 and the original records of his works were lost.

1922 After the 1917 Russian revolution, naval engineer Nicholas Minorsky emigrated to the USA where he worked with Steinmetz. Using his knowledge of automatic steering of ships, in 1922 he published a paper "Directional stability of automatically steered bodies", outlining the principles of 3 term controllers, the basis of modern PID control systems.

1922 German organic chemist Hermann Staudinger published his theories on polymers and polymerisation. He showed that natural rubbers were made up of long repetitive chains of monomers that gave rubber its elasticity and that the high polymers including polystyrene manufactured by the thermal processing of styrene were similar to rubber. Staudinger won the Nobel Prize for Chemistry for his research.

Polystyrene was originally discovered in 1839 by German apothecary Eduard Simon however he was not aware of its significance. It was first produced on an industrial scale by IG-Farbenindustrie in 1930

1923 The Marconi Company in Britain claimed to have made the first practical hearing aid called the Otophone. It used a carbon microphone and valve (vacuum tube) amplifier but with batteries it weighed an unpractical 7 Kg. It was not until 1953 with the advent of transistors and button cells that electronic hearing aids became truly practical.

1923 Quality engineers from the Western Electric Company working on sampling inspection theory developed graphs showing the probabilities of acceptance and rejection for different sampling plans. They identified the concepts of Consumer's Risk, the probability of passing a lot submitted for inspection which contains the tolerated number of defectives and Producer's Risk, the probability of rejecting a lot submitted for inspection which contains the tolerated percentage of defects. In 1926 they produced the first set of Sampling Inspection Tables for single and double sampling followed in 1927 by tables for determining the Average Outgoing Quality Limit (AOQL). The tables were published by Harold F. Dodge and Harry J. Romig in 1944 however these sampling and control techniques had already found wider use during World War II when standard military sampling procedures for inspection by attributes were developed by the US military and eventually published as Mil Std 105A in 1950.

The tables and techniques were designed to facilitate better production control, more efficient inspection and to avoid disputes and were very effective in achieving these goals over many years. Unfortunately they also encouraged the notion that faults were inevitable and the idea of an acceptable quality level placed a limit on aspirations to do better, effectively giving a licence to ship a few defects so long as the AOQL was acceptable. An example of "The Law of Unintended Consequences". The danger of these attitudes was finally realised in the 1980's when the public noticed that the Japanese, following principles introduced by W. E. Deming, coupled with Japanese work ethics, produced products which were significantly better than western offerings. Working to Six Sigma quality standards has been the West's response to the Japanese challenge of TQM.

"Statistics means never having to say you're certain" - Anon

1923 Danish chemist Johannes Brønsted and simultaneously British chemist Thomas Lowry proposed the Brønsted - Lowry concept of Acids and Bases which states that: An acid is a molecule or ion capable of donating a proton (That is a hydrogen nucleus H+) in a chemical reaction , while a base is a molecule or ion capable of accepting one. More simply: An acid is a proton donor and a base is a proton acceptor.

The same year Lewis proposed a more generalised concept which states: An acid is a molecule or ion that can accept a pair of electrons while a base is a molecule or ion that can donate a pair of electrons. This explains why metal oxides are basic since the oxide ion donates two electrons while non-metal oxides which accept two electrons to share with the non-metal atom are acidic.

1923 After seeing the design for a quartz crystal oscillator shown to him by fellow academic W. G. Cady, Harvard professor and inventor, George Washington Pierce, immediately recognised its potential and set about producing a much simpler design. Later that year he submitted a paper outlining his own "Pierce oscillator" to the Proceedings of the American Academy of Arts and Sciences and applied for a patent to protect the design. Its performance was no better than Cady's design but it was much simpler and cheaper, using a two terminal crystal and needing only one valve. Royalties from Pierce's patent portfolio were many times his Harvard salary.

The development of precision crystal controlled oscillators enabled the possibility of quartz controlled clocks which provided much better time keeping than mechanical designs.

1924 German psychiatrist Hans Berger was the first person to prove the existence of so called brain waves, electric potentials or voltage fluctuations in the human brain, using an an electroencephalograph to detect and amplify the signals. He experimented by attaching electrodes to the skull of his fifteen year old son Klaus, recording the first human electroencephalogram (EEG).

1924 French aristocrat who came to physics late in life, Prinz Louis-Victor Pierre Raymond, duc de Broglie, speculated that nature did not single out light as being the only matter which exhibits a wave-particle duality. He proposed that since light waves could be considered as particles the converse should be true and ordinary ``particles'' such as electrons, protons, or bowling balls could also exhibit the characteristics of waves. His theory was confirmed in 1927 by J.J. Thomson and others who demonstrated wave-like properties of the electron.

de Broglie was awarded the Nobel Prize in 1929 for his work on subatomic particles.

See more about Wave - Particle Duality

1924 The modern, moving coil, direct radiator, loudspeaker patented by Western Electric (Bell Labs) engineers Chester W. Rice and Edward Washburn Kellogg.

1924 The ribbon microphone and its converse the ribbon loudspeaker were invented by German engineers Walter Schottky and Erwin Gerlach working at Siemens. The ribbon microphone was constructed from an extremely thin concertina ribbon of aluminium placed between the poles of a permanent magnet.

1924 By sending radio waves vertically skywards and detecting the reflected signal, British engineer Edward Victor Appleton proved the existence of the ionosphere predicted by Heaviside and Kennelly in 1902. By measuring the time delay between the transmitted and reflected waves he was able to determine its altitude as 60 miles above ground. Ionospheric layers are useful in radio communications reflecting the waves around the Earth's curvature.

In 1926 he discovered a further, even more electrically conductive, layer at an altitude of 150 miles. This layer, named the Appleton Layer after him, is a more dependable reflector of radio waves reflecting the shorter radio waves, which pass through the Heaviside layer. Other ionospheric layers reflect radio waves sporadically, depending upon temperature and time of day.

Appleton's work on detecting signals reflected from distant objects formed an invaluable foundation for Britain's defence work on Radar technology before and during the Second World War and earned him the Nobel Prize for Physics in 1947.

See more about Ionisation Layers

1925 Electrical recording using a microphone, an amplifier using De Forest's Audion vacuum tube (valve) and an electrical disc-cutting head, in a system invented the previous year by Joseph P. Maxfield and Henry C. Harrison of Western Electric, was adopted by the Columbia and Victor record companies. Electrical playback also became available the same year using amplifiers and the Rice-Kellogg loudspeaker.

What is surprising is that the basic technologies for implementing electrical recording and play back had been available in the telephone industry since 1877 when Edison invented the phonograph but for almost fifty years the record industry had persevered with Edison's system of direct acoustic recording on to wax cylinders or discs using large recording horns which both limited and dominated the recording environment. Similarly playback was had remained mechanical over the same period using clockwork motors, acoustic pick-ups and clumsy horns which gave out limited sound volume.

1925 Between 1925 and 1935 American engineer and politician Vannevar Bush and colleagues developed a series of analogue computers which they called differential analysers. They were capable of solving differential equations with up to eighteen independent variables and were based on interconnected mechanical integrators constructed from gears and mechanical torque amplifiers with the output represented by distances or positions. The 1935 version weighed 100 tons and contained 2000 vacuum tubes, 150 motors, thousands of relays and 200 miles of wire. Processing analogue data is a key requirement of modern control systems, however analogue values can now be represented electrically and processed in linear integrated circuits or converted to digital form for manipulation by microprocessors.

1925 Swiss theoretician Wolfgang Pauli explained why electrons orbiting an atomic nucleus do not all fall into their lowest energy state due to attraction from the positive protons in the nucleus. He proposed that besides orbiting the atomic nucleus, as in the three state model proposed by Neils Bohr and Arnold Sommerfeld, the electrons also have spin properties. Thus the electron can have four quantum states characterised by 4 quantum numbers which define,

  • the distance of the electron from the nucleus,
  • its kinetic energy (based on its angular momentum),
  • its magnetic moment (based on the azimuth angle of the plane of the orbit)
  • plus the intrinsic magnetic moment of the electron itself due to its spin.

In 1928 Paul Dirac provided the theoretical justification for Pauli's proposition.

In 1930 Pauli also postulated the existence of a small a hypothetical, massless (he thought) and chargeless particle which he called the "neutron particle" (No relation to Chadwick's comparatively massive neutron) to explain how beta decay, the break-up of the atomic nucleus with the emission of an electron or "beta particle", could conserve energy, momentum, and angular momentum (spin). In 1933 Enrico Fermi, who further developed the theory of beta decay, resolved the confusion by renaming "Pauli's neutron" as the "neutrino" (the Italian equivalent of "little neutral one". Up to now (2015), the mass of the neutrino has not been determined with certainty.

Pauli further proposed the principle that no two electrons in an atom can occupy the same quantum state, now known as the Pauli Exclusion Principle. This principle also provided the theoretical basis for the Mendeléev's Periodic Table of Elements.

Pauli was awarded the Nobel Prize in 1945 for his discovery of a new law of Nature.

One of the giants of twentieth century theoretical physics Pauli was notorious for his rudeness. He was also known for the "Pauli Principle" which predicted disaster for any piece of apparatus with which he was involved.

1925 German physicist Werner Heisenberg proposed a new model for the structure of the atom with different quantised energy states represented by frequencies and intensities. At the suggestion of Max Born these were incorporated into matrices. Known as Matrix Mechanics theory, it was a mathematical abstraction, but based on observable qualities of the atom, since current methods at describing the atom with physical analogues of orbiting electrons could not account completely for its behaviour.

He was awarded the Nobel Prize for physics in 1932 for this work.

Heisenberg was appointed to be head of Germany's atomic weapons programme during World War II and although, through the pioneering work of Szilard, Hahn and Strassmann on nuclear fission, Germany was ahead of the Allies before the war, by 1945 they were still a long way from being able to produce an atomic bomb and never even achieved a chain reaction.

1925 Charles Ducas described a variety of practical ways for manufacturing printed circuits including etching, electroplating and printing with conductive inks. He also proposed multi-layer circuit boards and showed how to implement connections between the layers.

1926 Frenchman Cesar Parolini devised improved additive printing and plating techniques for printed circuit manufacturing methods, some of which had been described years before, but not implemented by Edison.

1926 Waldo L. Semon an American chemical engineer invented plasticised poly vinyl chloride (PVC). The plasticisers are smaller, oily molecules interwoven with the long polymer chains which allow them to slide over eachother and give the plastic its characteristic flexibility. Without these plasticiser additives PVC would be too brittle. Originally discovered by Baumann in 1872 PVC is now used extensively for insulating wires and cables.

1926 German engineers Eckert and Karl Ziegler patent first commercial injection moulding machine.

1926 Building on de Broglie's wave - particle duality hypothesis Austrian physicist Erwin Schrödinger formulated a theory for the behaviour of atomic particles which has the same central importance to Quantum Mechanics as Newton's laws of motion have for the large-scale phenomena of classical mechanics. Schrödinger's Wave Equation was proposed as an alternative to Heisenberg's Matrix Mechanics. It describes the atom in the form of the probability waves (or wave functions) that govern the motion of small particles, and it specifies how these waves are altered by external influences. He realized that the possible orbits of an electron would be limited to those accommodating standing waves, that is, with an exact number of wavelengths. This permits only a limited number of possible orbits and no possible orbits between them. Schrödinger's theory of Wave Mechanics explained the hitherto inexplicable behaviour of atomic particles by considering them as waves not particles and the wave equation predictions were borne out by experimental results. He considered his model closer to classical physical theory and less of an abstraction than Heisenberg's model. Paul Dirac later proved that these two models were equivalent.

Schrödinger contributed to many branches of physics including quantum theory, optics, kinetic theory of solids, radioactivity, crystallography, atomic structure, relativity and electromagnetic theory. In 1935 he published the famous Schrödinger's cat paradox which was designed to illustrate the absurdity of the probabilistic notion of quantum states. This was a thought experiment where a cat in a closed box either lived or died according to whether a quantum event occurred. The paradox was that both universes, one with a dead cat and one with a live one, seemed to exist simultaneously until an observer opened the box. In his later years he applied quantum theory to genetics. He coined the term "Genetic code"and published an influential book "What is Life" which inspired Watson and Crick in their search for the structure of DNA.

He also studied Greek science and philosophy and published his thoughts in his book "Nature and the Greeks".

He was awarded the Nobel Prize for physics in 1933.

Schrödinger's wave mechanics provided the foundation, built on by Heisenberg, Dirac and others, for explaining the behaviour of electrons, nuclei, atoms, molecules and chemical bonding, fundamental building blocks or processes used in galvanic cells, as well as nanotechnology and the phenomena of nuclear fusion and superconductivity, processes used in the generation and distribution of electric power. Quantum mechanics also represents behaviour of electrons and "holes" (the absence of electrons) in semiconductors and the process of electron tunneling used in Scanning Tunneling Microscopes and other electronic devices. For the future, research into the possibilities of quantum computers whose bits can be both 0 or 1 at the same time, depending on the electron spin, performing calculations at unprecedented speed are also founded on the quantum theories of Schrödinger, Heisenberg, Dirac and their successors.

It was almost forty years before before the principles demonstrated by Volta in his voltaic pile were successfully put to use by the telegraph pioneers in commercial products. In the case of Faraday's motor, it was almost sixty years before a market was created. Watch out for Schrödinger's kittens.

A man of many accomplishments Schrödinger's life was both colourful and complicated. He had an informal manner and throughout his life he travelled with walking boots and rucksack which raised a few eyebrows at the many conferences he attended. He served in Italy and Hungary during the First World War. Later he was an opponent of Nazi rule in Germany which brought him several brushes with authority. As an eminent physicist he also received many offers of positions in the worlds best universities and at various times he help posts at Graz, Berlin, Breslau, Zurich, Oxford, Princeton, Edinburgh, Rome, Dublin, Gent and Vienna. His relationships with women were however even more wide-ranging. He had numerous lovers with his wife's knowledge (even more Schrödinger's kittens) and she in turn was the lover of one of Schrödinger's friends. While at Oxford he brought his colleague Arthur March from Germany to be his assistant since he was in love with March's wife who was pregnant with his child and he lived openly with his new daughter and two wives one of whom was still married to another man. During his time in Dublin he fathered two more daughters with two different Irish women.

And in between he also found time to do a little physics....

1926 German physicist Max Born working at Cambridge found a way to reconcile particles with waves by treating Schrödinger's wave as the probability that an electron will be in a particular position.

The singer Olivia Newton-John is a grand-daughter of Born.

1926 German professor of physics at Leipzig University, Julius Edgar Lilienfeld emigrated to the USA and filed a patent for what would today be called a field effect transistor. It consisted of a semiconducting compound sandwiched between two metal plates, one of which was connected to a current source and the other connected to the output. The resistance of the semiconductor between the plates could be varied by means of a variable electric field created across it by a control signal connected to a third plate at the side of this sandwich and insulated from it. It worked in a way analogous to a vacuum tube and in 1930 Lilienfeld was granted a patent for "A method and apparatus for controlling electric currents". Other than Lilienfeld, nobody at the time seems to have recognised the device's potential and it faded into obscurity until it was rediscovered by William Shockley's patent attorneys, much to Shockley's chagrin when he independently conceived a similar device 20 years later.

1926 American engineer and physicist, Robert Hutchings Goddard successfully launched the world's first liquid fuelled rocket which he had designed and built. Between 1926 and 1941 Goddard and his team launched 34 rockets, achieving altitudes as high as 2.6 km (1.6 mi) and speeds of up to 885 km/h (550 m.p.h.).

He was the first scientist to realise the potential of missiles and space flight and contributed in bringing them to realization.

Goddard carried out extensive theoretical, experimental and practical work on rocket technologies from which he was awarded 214 patents for his inventions. Two of his patents, awarded in 1914, for a "multi stage rocket" and a "liquid fuelled rocket, fuelled with gasoline and liquid nitrous oxide" were important milestones in space flight.

In 1919 he published "A Method of Reaching Extreme Altitudes" outlining the mathematical theories of rocket flight and his research into solid-fuel and liquid-fuel rockets which is regarded as one of the classic texts on the science of rocketry and is believed to have influenced the work of German rocket pioneers Hermann Oberth and Wernher von Braun.

Like the Wright brothers, Goddard was not just concerned with propulsion, he also recognised the imporatnce of three-axis flight control which he successfully achieved by means of control systems using gyroscopes and steerable thrust.

His ideas were ahead of his time and often met with ridicule though he was supported by the Smithsonian Institution and after 1930 by the Guggenheim family. The importance of his work was not fully recognised by the public until after his death in 1945.

1926 Alfred Lee Loomis, a successful investment banker with a mathematics and science degree from Yale and a law degree from Harvard, used his immense wealth to pursue his interest in science by setting up his own research facility, the Loomis Laboratory, where he lived in Tuxedo Park, a residential enclave of the rich and famous in New York which gave its name to men's formal attire.

After World War I, in which he volunteered for military service, Loomis had amassed a fortune investing in utility companies during a period of rapid expansion collecting directorships in many banks on the way. He anticipated the 1929 Wall Street Crash converting his holdings into cash beforehand and buying depressed stocks cheaply afterwards. Accused of profiting from inside knowledge from his many business directorships and political contacts, a practice which was questionable but not considered illegal in those days, he withdrew from the financial business and devoted his many talents to his first love, the advancement of science, which he funded from his own resources.

Loomis's lab was not simply the plaything of a rich dilettante, it initially undertook serious research into high energy acoustics, chronometry, spectrometry and electro-encephalography. During the 1930s Loomis and his team worked on nuclear physics and radar projects and Europe's top physicists including Albert Einstein, Werner Heisenberg, Niels Bohr and Enrico Fermi as well as radio pioneer Guglielmo Marconi visited the lab which Einstein called the "Palace of Science".

The lab's military developments and researches into the possibilities of radar were at first scorned by the US military but their attention was grabbed in 1940 when the British Tizard Mission sought the help of the Tuxedo Park lab in the manufacture of Randall and Boot's cavity magnetron. It had a power output of 10 kilowatts at a wavelength of 10 centimetres, a thousand times more than the best American transmitter. Loomis was quickly appointed by Vannevar Bush to the National Defence Research Committee as chairman of the Microwave Committee and within six weeks he founded the famous MIT Radiation Laboratory, to which he transferred his Tuxedo Park activities. Known as the Rad Lab, its mission was to develop microwave radar systems based on the magnetron. Ernest Lawrence of the University of California helped Loomis to assembled a team of gifted young physicists to staff the Rad Lab and Loomis in turn helped Lawrence secure the funding for his second, "giant", (184 inch) cyclotron.

In 1942 when the highly secret programme, then known as the Manhattan Engineering District, later named the Manhattan Project, was set up to develop the atomic bomb the Rad Lab provided many of the early recruits.

The Rad Lab was at the forefront of fundamental theory and developments of microwave components and systems engineering during the war years until it was closed in 1945 after the war ended but its work was highly secret. Its results however were published in 18 volumes after 1947 as the MIT Radiation Laboratory Series, edited by Louis N. Ridenour which became the microwave engineers' bible.

1927 Heisenberg discovers the Uncertainty Principle. It is impossible to determine the position and momentum of a particle simultaneously. The more accurate one is measured, the more inaccurate the other becomes.

Einstein was very unhappy about this apparent randomness in nature. His views were summed up in his famous phrase, "God does not play dice".

1927 British physicist George Paget Thomson, son of J.J. Thomson, discoverer of the electron, working with Alexander Reid at Aberdeen University and simultaneously and independently, Americans Clinton Joseph Davisson working with Lester Halbert Germer at Western Electric Labs, confirmed de Broglie's hypothesis of the wave particle duality of the electron. Thomson created transmission interference patterns by passing an electron beam through a thin metal foil and Davisson created diffraction patterns of electron beams reflected from metallic crystals, both confirming the wave nature of the electron.

Thomson and Davisson were awarded the Nobel Prize for physics in 1935.

1927 German physicist Friedrich Hund was the first to notice the possibility of the phenomenon of quantum tunnelling which he called "barrier penetration" a process by which a particle can appear to penetrate a classically forbidden region of space passing from point A to point B without passing through the intermediate points. This is a manifestation of de Broglie's wave - particle duality theory with the electron acting like a wave rather than a particle. The phenomenon can be characterised by Schrödinger's wave equation which tells us that the energy associated with an electron is not discrete but has a probabilistic level. As a consequence a certain number of electrons will have more than enough energy to jump an energy gap that would normally be too wide. The effect is that electrons appear to tunnel through a barrier which we would normally expect bar them.

1927 In the USA a Lead Acid car battery cost $70 while a typical car cost $700. Today a car battery still costs $70 while car prices have skyrocketed by comparison.

1927 Invention and patent application by French company Chauvin Arnoux for the "Contrôleur Universel", the forerunner to the Multimeter. Despite this patent, the invention was to become copied throughout the world.

1927 In a technical analysis of closed loop control systems, American engineer Harold Steven Black working at Bell Labs demonstrated the utility of negative feedback in the design of telephone repeater amplifiers to reduce distortion. Previous studies on feedback control systems by Airy and others (and later by Nyquist) focussed of system stability. Black investigated ways of achieving the low distortion necessary for high capacity multiplex channels and showed that by inserting a sample of the amplifier output signal, in reversed phase, into the amplifier input the degree of distortion due to the amplifier could be reduced to almost any desired level at the expense of amplification.

1927 Generic patent for flexible printed circuits as well as three dimensional circuits and printed inductors by applying conductive materials to a flexible substrate was published by Frederick Seymour.

1927 Mormon farm boy from Idaho, Philo Taylor Farnsworth conceived the idea of the world's first practical all electronic television system while still in high school. An electronic system had been proposed earlier by Campbell Swinton but due to the primitive state of the technology at the time it was never built. Farnsworth built a working system using the Farnsworth orthicon or image dissector tube and patented his design in 1927 while still only 21 and successfully fought off the patent claims from the mighty RCA. Nevertheless despite paying royalties to Farnsworth, RCA ultimately found ways around the patents and promoting their own man, Zworykin, as the originator of the television system they finally put Farnsworth out of business. Like Armstrong who had similar battles with RCA, Farnsworth's private life suffered and he became an embittered alcoholic in his early 30's. He spent much of his later life and all of his money in a fruitless pursuit of nuclear fusion.

1927 The Quartz Clock invented by Canadian born Warren Marrison working at Bell Labs. He demonstrated the superior accuracy of clocks using crystal controlled oscillators kept in time by the regular vibrations of a quartz crystal. Initially they were used for precise telecommunications frequency standards but today they are found in every battery powered quartz watch and they provide the microprocessor system clock in every personal computer.

1927 British engineer Thomas Graeme Nelson Haldane designed and patented the first practical domestic heat pumps, devices which could be used for both heating and cooling. He built small experimental heat pumps for extracting heat from mains water in Scotland.

The principle had first been proposed by Lord Kelvin in 1852 using air as the working fluid in a system he called a heat multiplier. At that time, when the UK had a plentiful supply of coal, there was no commercial interest in his idea.

1928 British physicist Paul Adrien Maurice Dirac working on quantum field theory at the Cavendish Laboratory in Cambridge combined the theories of quantum mechanics of Bohr and Pauli with Maxwell's electromagnetic field theory to model the properties of the electron. He introduced the concept of special relativity and electron spin, which gave the electron its internal magnetic properties and which Schrödinger had not been aware of, into Schrödinger's wave equation to develop the Dirac equation which was consistent with both Heisenberg's matrix mechanics and Schrödinger's wave theory. Dirac's model could treat the electron as either a wave or a particle and still get the right answers. It marked the beginning of Quantum Electrodynamics - QED.

In 1931, Dirac used his equation to predict the existence of a particle with the same mass as the electron but with positive rather than negative charge. This "anti-particle", now called a positron, was detected by American physicist Carl Anderson in 1932 and all particles are now known to have anti-particles.

Dirac shared the Nobel Prize for physics with Schrödinger in 1933.

Unlike Schrödinger, Dirac's shyness was legendary. When informed that he had won the Nobel Prize he told Rutherford that he did not want to accept it because he disliked publicity. Rutherford told him that refusing the prize would bring even more publicity!

1928 Bell Labs engineer Ralph Hartley devised measures for quantifying the information content in electrical signals. He showed that a single pulse can represent M different, distinct messages given by


Where A is the transmitted signal amplitude in Volts and ΔV is the resolution precision of the receiver, also in Volts.

He also showed that the data signaling rate R can be represented by


Where log2(M) is the information sent per pulse in bits/pulse

and fp is the pulse or symbol rate in symbols per second or Baud.

1928 Swedish born American engineer Harry Nyquist showed that up to 2B independent pulse samples could be sent through a system of bandwidth B. This was the basis of the Sampling Theorem, later formulated by Shannon, which states that a signal can be exactly reproduced if it is sampled at a frequency F, where F is greater than twice the maximum frequency in the signal. Very important for specifying the sampling rate in monitoring and control systems but also the foundation on what digital communications are based. Nyquist went on to develop stability criteria for feedback control systems.

1928 Another Swedish born American engineer John Bertrand Johnson working at Bell Labs identified the spectrum of random white noise found in electrical circuits as due thermal agitation of electrons in the conductors. His colleague Harry Nyquist (see above) showed that the maximum noise power P in Watts which can be transferred into a matched circuit is independent of the resistance and is given by

P = K T Δf

Where K is Boltzmann's constant in Joules per degree Kelvin, T is the absolute temperature in degrees Kelvin and Δf is the bandwidth in Hertz over which the noise is measured.

Such thermal noise is now called Johnson noise.

1928 Rocket engineer Herman Potocnik a.k.a. Hermann Noordung born in Slovenia, published "Das Problem der Befahrung des Weltraums - der Raketen-Motor" "The Problem of Space Travel - The Rocket Motor" in which he was the first to envisage the possibility of geostationary artificial satellites and to calculate their orbits. He outlined the idea of orbiting manned space stations with the crew in radio contact with the ground. Both rocketry and radio communications were still in their infancy in those days and while Potocnik's ideas were interesting, there was no practical way of implementing them with the technology of the day. Though his book was translated into Russian and parts of it into English, it had little impact at the time and Potocnik died in poverty at the age of 36.

It was not until 1945 that the idea of worldwide radio communications using dedicated geostationary communications satellites was proposed by Arthur C Clarke.

1928 Indian physicist Chandrasekhara Venkata Raman, working at the University of Calcutta (Now Kolkata), discovered that when monochromatic light impinges on the molecules of the transmitting medium, the light beam causes the molecules in the medium to vibrate exciting them from a ground state to a virtual energy state. When the molecule relaxes it emits a photon as it returns to a different ground state. The frequency shift in the emitted photon away from the frequency of the original excitation corresponds to the difference in energy between the original ground state and this new state. (The photon energy E =   Planck's Law).Thus the photons in light beam may take some energy from, or impart some energy to, the molecules. The increased energy photons in the beam are manifest as a higher frequency spectrum component in the light and similarly the lower energy photons appear as a lower frequency spectrum line. The scattered light thus has a prominent spectral line corresponding to the original beam and additional spectral lines which are characteristic and unique to the molecules of the substance of the transmission medium. This property is used in chemical and physical spectroscopy to identify materials and also in forensic work by law enforcement agencies to detect drugs and other materials.

This energy scattering is known as Raman Scattering or the Raman Effect and the discovery was considered to be confirmation of the quantum effects of light.

Raman was awarded a Nobel prize in 1930 for his discovery.

1929 The kinescope, a cathode-ray tube with all the features of modern television picture tubes invented by Russian born American, Vladimir Zworykin, working for RCA. In 1923 while working at Westinghouse, Zworykin applied for a patent on the iconoscope, a tube based on Campbell-Swinton's proposal of 1911, designed to create the images in his early television cameras but it was not used commercially and the patent was not granted until 1938. Zworykin was told by Westinghouse"to find something more useful to work on". The imaging technology on which television cameras were based is in fact descended from Farnsworth's image orthicon but RCA's PR machine claimed that Zworykin laid the foundations of today's television systems in 1923, ignoring the contributions of Farnsworth, the farm boy from Idaho who is almost forgotten today.

1929 Initially following in the footsteps of Vesto Slipher and Harlow Shapley, American astronomer Edwin Hubble, working at the Carnegie Observatories in Pasadena, ably assisted by unschooled Milton Lasell Humason, formulated the empirical Redshift Distance Law of Galaxies, nowadays known simply as Hubble's Law. Hubble and Humason measured redshifts of more stars and the relative brightness of Cepheids in a number of distant galaxies and used Leavitt's period-luminosity relation and the inverse square law to determine their relative distances. He went on to plot the stellar redshifts against the associated distances and found that the redshift of distant galaxies increased in direct proportion to their distance. The fact that the more remote stars were moving faster explained why they were further away and showed that not only was the universe expanding but that at some time in the past, the entire universe would have been contained in a single point. This event was later estimated to be been approximately 13.7 billion years ago.

Hubble's Law is expressed by the equation v = H0D, where D is the distance to a galaxy with velocity v and H0 is the Hubble Constant of proportionality.

British astronomer Fred Hoyle who supported an alternative steady state model of the universe in 1949 sarcastically called this event the Big Bang and the name has stuck ever since.

Prior to the publication of Hubble's Law, the conclusion that the universe could be expanding had already been reached by others following a purely mathematical route but they had no evidence to prove it. Albert Einstein's general theory of relativity theory (and Newton's Laws) had been unable to explain why the gravity between all the matter in the universe did not cause it to contract. He overcame this paradox by inventing the cosmological constant, a mathematical fiddle factor for which there was no physical evidence, to justify a static model. It was a notional force pushing the universe apart which acted in the opposite direction to gravity on a cosmic scale, but not at short distances.

Rejecting Einstein's mathematical contrivance, Russian mathematician Alexander Friedmann investigated three possibilities, a contracting universe, an expanding universe and a steady state model and published his findings in 1922 in Zeitschrift für Physik. He ruled out the static model which he pointed out would be unstable since the movement of the slightest mass anywhere in the universe would destroy the equilibrium and lead to either an explosive expansion or a cataclysmic contraction. He explained that if the universe was started by some original great explosive force which blew it apart, its behaviour would depend on the magnitude of the force and the amount of matter in the universe. If the density of stars in the universe was low and the force was high, the stars would keep travelling outwards forever. If on the other hand the density was high and the force was small, inertia would keep the stars travelling outwards until gravity eventually takes over pulling them back and the universe would start to contract again.

Unfortunately Friedman did not live to see his predictions confirmed by Hubble. He died from typhoid fever in 1925 at the age of 37.

Independently, Monsignor Georges Henri Joseph Édouard Lemaître a Belgian priest, professor of physics and astronomer at the Catholic University of Leuven who liked to keep one foot in the church and the other in the observatory was studying the same gravitational paradox and came to similar conclusions to Friedmann. The notion that the universe could have originated at a precise point in time resonated with his Christian creationist beliefs. In 1927, two years before Hubble's discovery, he published "A homogeneous universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae" in which he explained his theory of an expanding universe governed by a relationship similar to Hubble's Law. It was published in French in the Annales de la Société Scientifique de Bruxelles which was not widely read outside of Belgium, so it had little impact.

His ideas were however picked up by Arthur Eddington who invited him to talk about the relationship between the universe and spirituality at a meeting of the British Association in 1931. Lemaître explained that the expanding universe implied that going backwards in time, all the mass of the universe would have contracted into a single point which he called the Primeval Atom at a finite time in the past before which time and space did not exist. He compared the origin of the universe to "the Cosmic Egg exploding at the moment of the creation".

Until Hubble came along, there was no proof of Friedmann's or Lemaître's hypothesis. Einstein mocked Lemaître saying "Your calculations are correct, but your physics is abominable." Hubble's observations however proved that Einstein was wrong and Einstein admitted in 1930 that "The cosmological constant was the biggest mistake of my life."

1930 The works of British physical chemist John Alfred Valentine Butler and German surface chemist Max Volmer on the theoretical basis of kinetic electrochemistry were summarised in the fundamental Butler-Volmer equation. It shows that the current flowing at an electrode is the sum of the anodic and cathodic contributions. It is also directly proportional to the area of the electrodes and increases exponentially with temperature.

1930 Russian Wladimir Gusseff invents Electro-Chemical Machining (ECM) using electrolytic erosion, a galvanic process essentially the reverse of electroplating which allows the machining of complex shapes in very hard metals. The work piece forms the anode and the shaped tool forms the cathode and they are supplied with a low DC voltage of about 40 Volts. Electrolyte is pumped through the gap between the tool and the work piece and metal is removed from the work piece in the vicinity of the tool by galvanic action as in a battery. The flowing electrolyte removes the dissolved metal so there is no tendency for it to be deposited on the cathodic tool.

Note This is different from the more common machining process known as Spark Erosion or Electro-Discharge Machining (EDM). In this process the work piece and the tool are immersed in a bath electrolyte, however the gap between the tool and the work piece is fed with a high frequency pulsating voltage which creates a spark across the gap which in turn vaporises the metal of the work piece in the proximity of the tool. It was invented by Russian brothers B.R. and N.I. Lazarenko in 1943.

Both of the above processes are used to make the intricate shapes used in injection moulding tools.

1930Lilienfeld gave a paper on electrolytic capacitors before the American Electrochemical Society in which outlined the fundamental theories and practice for the design of these components, still in use today.

Electrolytic capacitors have a very high capacitance per unit volume allowing large capacitance values to be achieved making them suitable for high-current and low-frequency electrical circuits. The construction is similar to a spiral wound battery with two conducting aluminium foils, one of which is coated with an insulating oxide layer which acts as the dielectric, and a paper spacer soaked in electrolyte, all contained in a metal can. The aluminium oxide dielectric can withstand very high electric field strengths, of the order of 109 volts per metre, before break down. This allows the use of very thin dielectric layers to be used and this in turn permits a much larger area of the capacitive plates to be accommodated within the space inside the case. These characteristics enable very high capacitance values to be achieved.

The foil insulated by the oxide layer is the anode while the liquid electrolyte and the second foil act as cathode. They are thus polarized and so must be connected in correct polarity to avoid breakdown.

Electrolytic capacitors can store a large amount of energy and are often used in battery load sharing applications to provide a short term power boost. See also Supercapacitors and Alternative Energy Storage Methods.

1930 22 year old student, Frank Whittle, attending the RAF officers training school at Cranwell, designed the world's first high power jet engine, a single stage machine with a centrifugal compressor for aviation applications, which his commanding officer arranged for him to show to the UK Air Ministry. The Air Ministry who had no experience in such matters passed the design for evaluation to Alan Arnold Griffith, an engineer at the Royal Aircraft Establishment. But Griffith had his own ambitions and alternative ideas for gas turbine propulsion preferring an axial flow turbine driving a propeller. He declared Whittle's design to be impracticable and so it lost the support of the Air Ministry. Undaunted Whittle persevered and patented his jet a few months later.

After Cranwell, he went on to study mechanical engineering at Cambridge University and while still there he was reminded in 1935 by the Air Ministry that the patent for his jet was about to lapse and that they had no intention to pay its renewal fee of £5. Short of cash himself and seeing no hope of his engine becoming a reality, he let the patent lapse.

Meanwhile at the University of Göttingen in in Germany, Hans-Joachim Pabst von Ohain, aware of Whittle's patent, started work in 1935 on his own design for a jet engine which he patented in 1936. It was quickly picked up by the Heinkel aircraft company who went on to manufacture von Ohain's designs.

In contrast, Whittle struggled to get financial support and, dogged by further unhelpful reports from A.A. Griffith, he received lukewarm support from the government but no money so he had to set up his own company "Power Jets" with private backers providing minimal funding to develop the engine. Desperately short of cash they managed to produce an impressive working prototype in 1937 when the government finally woke up to its importance. Despite the growing threat of war with Germany, still no government cash was forthcoming until mid 1938 when Power Jets eventually received a development contract worth £5,000 accompanied by grant conditions which made Power Jets subject to the Official Secrets Act making it difficult for them to raise further private equity.

Starved of funds, Power Jets were overtaken by the well funded Heinkel who flew their first jet aircraft the Heinkel He-178 on 27 August 1939. The first British plane powered by Whittle's jet was a Gloster which took off on 12 April 1941.

Suffering from ill health and mental strain, Whittle's reward for his pioneering work and personal sacrifices as part of the war effort was that his technology had been given to the USA as part of the Tizard Mission and his company was nationalised in 1944 for which he was offered no compensation since he had previously offered his shares to the Air Ministry. The government later relented and paid him off with the princely sum of £10,000.

Belatedly he was showered with honours, but not when he needed them most.

1931 Wallace Hume Carothers working at DuPont labs created Neoprene the first successful synthetic rubber. Neoprene's combination of properties, resistance to chemicals, toughness and flexibility over a wide temperature range made it suitable for the design of pressure vents which facilitated the construction of recombinant batteries and for gaskets used in battery enclosures. Searching for synthetic fibres Carothers also invented Nylon in 1935, now also used to produce a wide range of injection moulded components from containers to gears. In the USA, nylon stockings went on sale for the first time in 1940 and four million pairs were sold in the first few hours.

Carothers was a manic depressive alcoholic who, despite his great achievements, considered himself a failure. He founded and was head of Du Pont's research group working on polymers and polymerisation which was one of the most successful groups in the history of polymer science. He committed suicide in 1937 at the age of 41 by taking cyanide a year after his marriage and the untimely death of his sister.

1931 The portable Metal Detector patented by American engineer Gerhard Fischar. Metal detectors use a variety of methods to detect small changes inductance or perturbations in the local magnetic field when the detector is near to a metal object. See also Alexander Graham Bell's detector.

1931 Irish chemical engineer James J. Drumm introduces the alkaline Nickel Zinc Drumm traction battery after five years of development. A variant of the Michaelowski chemistry, they had a cell voltage of 1.85 volts and charge / discharge rates 40% higher than Nickel Iron cells with which they were intended to compete but they suffered from a low cycle life and high self discharge rate. Drumm built four trains to use his batteries but with the outbreak of World War II it became impossible to obtain both orders and raw materials and the company folded in 1940.

1931 French engineer H. de Bellescize applied for a UK patent for an improved homodyne radio tuning circuit. It was the first automatic frequency control (AFC) system and the first circuit to incorporate the basic features of a phase locked loop (PLL). The following year de Bellescize published a description of his design in "Onde Electrique", volume 11, under the title "La Réception Synchrone". The original homodyne receiver was designed in 1924 by a British engineer named F.M. Colebrook in an attempt to improve on Armstrong's superheterodyne receiver. Colebrook's design mixed the received signal with a locally generated sine wave at the same frequency as the carrier wave to extract the signal from the carrier in a simple detector - essentially a zero intermediate frequency (IF). De Bellescize improved on this by detecting any difference between the received carrier frequency and the local oscillator frequency and using the difference signal to adjust the oscillator frequency till it matched exactly the carrier frequency thus ensuring perfect synchronisation of the two signals and the desired zero IF. Further improvements to the design were made by british engineer D.G. Tucker and others and the tuner was renamed the synchrodyne.

The phase locked loop (PLL) is now a fundamental building block in synchronisation and control circuits and complete complete PLL circuits are available in low-cost IC packages.

1931 English engineer Alan Dower Blumlein invented stereo sound. A prolific inventor Blumlein made many advances in the field of acoustics and made significant contributions to Britain's first all electronic television service. During the war years he applied his considerable skills to Radar design. He died in a plane crash in 1942 at the age of 38 while testing the H2S Airborne Radar equipment for which he had designed many of the circuits. He was awarded 132 patents in his short life.

1932 German electrical engineers Max Knoll and Ernst August Friedrich Ruska invented the first transmission electron microscope (TEM). One of the first applications of quantum mechanics theory, it depends on wave properties of the electron rather than it's particle properties. Instead of a light beam, it used an electron beam which has a wavelength much shorter than a light beam and can thus provide a much higher resolution. Focusing was by means of magnetic coils acting as lenses and by 1933 a magnification of 7000 times was achieved, far in excess of what was possible with visible light. The beam is detected after passing through a very thin specimen to create an image. It is now an essential tool for investigating the structure of materials.

Fifty four years later Ruska was belatedly awarded a Nobel Prize jointly with Binnig and Rohrer in1986 in recognition of his fundamental work on electron optics and the invention of the electron microscope.

Knoll went on to invent the scanning electron microscope (SEM) in 1935 however the modern SEM was invented by Oatley in 1952.

See also STM

1932 First practicalFuel Cell system (Alkaline with porous electrodes) demonstrated by English mechanical engineer Francis Thomas Bacon, a direct descendant of Sir Francis Bacon, the 17th century philosopher.

1932 The Cavendish Laboratory's annus mirabilis. English engineer and physicist John Douglas Cockcroft and Irish physicist Ernest Thomas Sinton Walton, working under Rutherford at the Cavendish Laboratory, constructed the world's first nuclear particle accelerator for investigating atomic structures, now known as the Cockcroft-Walton accelerator, or more colourfully as an atom smasher. It was a 750,000 Volt linear accelerator which they used to bombard a Lithium target with protons (Hydrogen nuclei) raised to an energy level of 750,000 electron Volts (750 KeV). It used a cascade of simple voltage multiplier circuits based on capacitors and diodes to generate the very high voltages needed in what is now known as the CW multiplier or CW generator named after the inventors. Like many UK university experimenters at the time they had to improvise because of a shortage of resources, using amongst other things car batteries, and for the glass cylinders surrounding the electrodes they used glass tubes from petrol pumps they used Harbutt's plasticine to seal the joints in the vacuum tubes. Very high energies were needed to overcome the repulsion of the positively charged protons by the positively charged Lithium nucleus. The Lithium nucleus contains 3 protons and 4 neutrons. The high energy proton bombardment caused the Lithium nucleus to disintegrate into 2 alpha particles (Helium nuclei), each composed of 2 protons and 2 neutrons. This was the first disintegration of an atomic nucleus by controlled, artificial means, the first artificial nuclear reaction not utilizing radioactive substances, the first use of a particle accelerator to split the atom and the first artificial transmutation of a metal into another element.

In fact Rutherford had actually already split the atom in 1917 using a radioactive source, however he had merely knocked a proton out of the nucleus. Cockcroft and Walton had actually split it in two.

The speed of the resulting helium nuclei was measured and the kinetic energy calculated. It was found to be equivalent to the reduction in the combined mass of the resulting helium nuclei from the combined mass of the original lithium and hydrogen nuclei. This was the first verification of Einstein's law, E = mc2.

The "Daily Express" headline on the news of their success was "The Atom Split, But World Still Safe".

Cockcroft and Walton were awarded the Nobel Prize for physics in 1951.

1932 Shortly after Cockroft and Walton's experiments (See previous item) American physicist Ernest Orlando Lawrence working at the University of California, Berkeley introduced the Cyclotron, a much more elegant and ingenious design for a particle accelerator. It consisted of two hollow "D" shaped electrodes, known as the "dees", resembling a flat, pancake shaped tin can cut into two halves, into which charged particles (ions or electrons) could be introduced. These electrodes were contained in a disc shaped glass vacuum chamber which was in turn held between the two poles of a powerful magnet creating a magnetic field perpendicular to the "dees". See Cyclotron diagram

When a high frequency, high power, alternating voltage is connected across the gap between the "dees" and charged particles are injected into the chamber near the centre, the particles move in a circular arc, at right angles to the magnetic field, in the plane of the "dees" due to the interaction of the moving charged particles (essentially an electric current) with the magnetic field. See Lorentz Effect in the page about electrical machines.

Each time the particles pass the gap between the "dees" they are accelerated due to the electric field across the gap. The frequency of the alternating electric field is timed so that its electrical polarity changes in exactly the time that the particles take to make half a revolution of the chamber so that the electric field across the gap is always in the same direction as the movement of the particles. In this way the particles trace a spiral path between the magnetic poles, receiving an energy boost each time they cross the gap between the "dees", gradually building up to very high energy levels. Because the particle beam starts with zero radius it does not need a source of high energy particles so that it can use a simple low kinetic energy ion source such as an ionised gas.

Lawrence's first cyclotron measured just 11 centimetres (4.5 inches) in diameter and boosted Hydrogen ions to an energy of 80,000 electron Volts (80 KeV). The University of Vancouver's TRIUMF cyclotron, built in 1974, is 18 metres in diameter and can accelerate Hydrogen ions to up to energies of 520 MeV.

In 1939, Lawrence was awarded the Nobel Prize in Physics for his work on the cyclotron and its applications and chemical element number 103, discovered in 1961, is named "Lawrencium" in his honour.

1932 34 Years after the discovery of the electron and the proton, English physicist James Chadwick another of Rutherford's students working at Cambridge University finally isolates the Neutron confirming Rutherford's predictions of a heavy neutral particle twelve years earlier. Physicists soon found that the neutron made an ideal "bullet" for bombarding other nuclei. Unlike charged  particles, it was not repelled by similarly charged particles and could smash right into the nucleus. Before long, neutron bombardment was applied to the uranium atom, splitting its nucleus and releasing the huge amounts of energy predicted by Einstein's equation E = mc2. See Fermi (1942)

1932 Within seven months of the discovery of the neutron, Hungarian physicist Leo Szilard conceived of the possibility of a controlled release of atomic power through a multiplying neutron chain reaction and that this could be used to build a bomb. He fled Germany in 1933 to escape Nazi persecution and in 1934 filed a patent application for the atomic bomb, outlining the concept of using neutron induced chain reactions to create explosions and the key concept of the critical mass.

Fearful of German intentions with nuclear weapons and disturbed by the lack of American action, in 1939 Szilard persuaded Albert Einstein to write to President Roosevelt, urging him to initiate an American atomic weapons programme. He was rewarded for his pains by Major General Leslie Groves, leader of the Manhattan Project designing the atomic bomb, who in 1943, forced Szilard to sell his atomic energy patent rights to the U.S. government.

In like manner in 1942 the Russian nuclear physicist Georgy Nikolaevich Flerov noticed that articles on nuclear fission were no longer appearing in western journals from which he concluded that research on the subject had become secret, prompting him to write to Premier Joseph Stalin insisting that "we must build the uranium bomb without delay." Stalin took the advice and appointed Igor Vasilevich Kurchatov, director of the nuclear physics laboratory at the Physico-Technical Institute in Leningrad, to initiate work on Russia's bomb. Their first nuclear bomb was finally tested on 29 August 1949 near Semipalatinsk on the steppes of Kazakhstan. Flerov and Kurchatov both received the Soviet Union's highest award, the title of Hero of Socialist Labour and the Gold Star medal.

1932 Just when we thought we had an elegant and simple explanation of the structure of matter with three sub-atomic particles, a nucleus of protons and neutrons with electrons orbiting around it, along came quantum mechanics in the 1920's and shook the foundations of physics. But it didn't end there, the detection in 1932 by Anderson of the positron predicted by Dirac indicated the existence of a lower level of elementary particles which make up the basic building blocks of the sub-atomic particles. It initiated the discovery over the next 50 or more years of whole families of elementary particles including Leptons, Quarks, Bosons, Mesons and Baryons and each family may include a dozen or more fundamental particles many of which have corresponding anti-particles. Examples are Muons, Gluons, Pions, Kaons and the whimsically named Up, Down, Top, Bottom, Strange and Charm Quarks to name but a few. While this is interesting, nobody has yet found practical applications for these particles, but then Rutherford did not foresee any use for nuclear energy when he discovered nuclear radiation.

1932 Russian physicist Igor Tamm proposed the concept of the phonon, a quantum of vibrational or kinetic energy, analogous to the photon, which is a quantum of light energy. These energy bundles represent the molecular vibrational state or the kinetic energy of a vibrating crystal lattice whose average kinetic energy is measured by its absolute temperature. Electrical and thermal conductivity can be explained by phonon interactions. Like photons, phonons have the characteristics of both waves and particles.

1932 G.W. Heise and W.A. Schumacher construct the first zinc air battery. High energy density primary cells, they were used to power Russia's Sputnik 1 in 1957.

1932 Sabine Schlecht and Hartmut Ackermann working in Germany invent the porous sintered pole plate which provides a larger effective electrode surface area and hence lower internal impedance and higher current capabilities bringing about major improvements to Nicad battery design.

1932 Following on the theoretical work on distortion reduction by means of feedback control systems by his colleague Harold Black at Bell Labs, Harry Nyquist proposes a method for determining the stability of feedback control systems. Known as the Nyquist stability theorem it was developed from the study of the behaviour of negative feedback amplifiers but it has universal applicability being applied to mechanical systems (position, speed, temperature, pressure controls) as well as electrical systems (voltage amplitude, frequency and phase controls) and even non physical models such as the national economy. It is used as a development tool to ensure stability of electronic control and protection circuits.

See also Closed Loop Control Systems for an explanation and for a description of earlier systems.

1932 Fibreglass, like glass, has been "invented" many times over. The first glass fibres of the type that we know today as fibreglass were discovered by accident by Dale Kleist working at Corning Glass. While attempting to weld two glass blocks together to form an airtight seal, a jet of compressed air unexpectedly hit a stream of the molten glass and created a shower of glass fibres indicating an easy method to create fibreglass. Fibreglass insulation had been patented in 1836 by Dubus-Bonnel, produced in volume by Player in 1870, patented again by Hammesfahr in 1880 and re-invented by Boys in 1887, however Russel Games Slayter of Owens-Corning was granted a patent for "Fiberglas" in1938.

The term 'fibreglass' is often used imprecisely for the composite material glass-reinforced plastic (GRP).

A fibreglass mat is an essential component used to absorb and immobilise the acid electrolyte in AGM Lead Acid batteries. Fibreglass composites are also used extensively for high power cell and battery casings.

1933 The "Dassler patent" recognized the oxygen cycle and recombination as fundamental principles of the sealed nickel-cadmium battery.

Research into improved nickel cadmium batteries by Schlecht, Ackermann and Dassler was driven by the need for light weight aircraft starting batteries.

1933 Walter Meissner and Robert Ochsenfeld discovered that when a superconducting material is cooled below its critical temperature magnetic fields are excluded or repelled from the material. This phenomenon of repulsion was discovered by Faraday and is known as diamagnetism. The low temperature effect is today often referred to as the "Meissner effect".

1933 The first injection moulded polystyrene articles produced.

1933 Reginald O. Gibson and Eric William Fawcett, ICI chemists produced Polyethylene a polymer of ethylene gas. Like many chemical developments it was discovered by accident, this time while reacting ethylene and benzaldehyde at high pressure. Now used extensively in the electrical industry as an Insulator ICI gave it the name Polythene.

1933 Radio pioneer Armstrong patented Frequency Modulation (FM radio) as a way of reducing interference on radio transmissions. Since most electrical noise produces amplitude variations in the signal, Armstrong's system involved varying the frequency of the radio carrier wave (rather than the amplitude as in AM radio) in synchronism with the amplitude of the voice signal. By clipping the noisy signal the noise can be eliminated. The idea which revolutionised radio reception was at first rejected then stolen by his old friend David Sarnoff the founder and CEO of RCA in which Armstrong was a major shareholder.

Armstrong had previously fought a legal battle all the way to the U.S. supreme court over his 1912 invention of the regenerative radio receiver which amplified weak radio signals by feeding them back through a triode amplifier valve (tube). However in 1920 when the value of Armstrong's invention became known, Lee De Forest claimed ownership of the regeneration principle because it used his audion. Unfortunately after 12 years of litigation, the supreme court, not familiar at that time with such technical distinctions, found in De Forest's favour.

Like Farnsworth before him, Armstrong suffered at the hands of RCA. Short of funds and faced with more years of costly and heartbreaking litigation against former friends over his FM patents, in January 1954 Armstrong put on his hat, his overcoat and his gloves, stepped onto the ledge of his 13th floor apartment building in New York City and plunged to his death. His wife who had contributed to Armstrong's depression by refusing to help fund his litigation against RCA, continued it herself and eventually won.

1933 US patent awarded for flexible printed circuits made by Erwin E. Franz by screen-printing or stenciling a paste loaded with carbon filler onto cellophane, followed by a copper electroplating step to reduce the resistance. He also proposed using flexible folding circuits for windings in transformers.

1934 Lead acid batteries with gelled sealed cells were first manufactured by Elektrotechnische Fabrik Sonneberg in Germany.

1934 Invention of the transformer-clamp by Chauvin Arnoux, the very first current measuring clamp.

1935 The first practical Radar (RAdio Detection And Ranging) system was produced by the Scottish physicist Robert Alexander Watson-Watt a direct descendent of James Watt the pioneer of the steam engine. As fears of an impending war grew, he had been tasked by the Air Ministry to come up with a radio death ray to disable enemy aircraft, however he informed them it was not possible and proposed instead the system we now call Radar for detecting the presence of aircraft before they came into sight. This was accomplished by sending out powerful radio pulses and detecting their return after reflection by the aircraft and computing the distance from the time it took the pulses to return. Large directional antennas were used to concentrate the signals and provide an indication of the bearing of the target. Being a two way system, one of the major problems he had to overcome was to get very sensitive receivers to work in close proximity to very high power transmitters without being swamped. Watson-Watt received a knighthood in recognition of his achievements.

Ironically, after the war, Watson-Watt was amongst the first unsuspecting drivers to be caught in a Radar speed trap.

1935 German physicist Oscar Ernst Heil, working at Berlin University was granted a British patent for "Improvements in or relating to electrical amplifiers and other control arrangements and devices". His design was essentially an insulated gate field effect transistor (IGFET). Using semiconducting materials such as Tellurium, Iodine, Cuprous oxide or Vanadium pentoxide to form a resistor between two terminals, he applied a voltage across the device. By means of a third control terminal he created an electrostatic field across the device at right angles to the current and by varying the voltage on this control terminal he was able to vary the resistance of the semiconductor and thus modulate the current through an external circuit.

Heil's transistor was never developed into a practical product. Semiconducting materials of sufficient purity were not available at the time and in the period leading up to and during World War II the scientific communities of whomever he happened to be working for had other priorities.

Heil however had other interests which benefited from the new focus on research applicable to military applications. He had married Agnessa Arsenjeva a Russian physicist while working in Russia. In 1935, the same year that he was granted the patent for his semiconductor amplifying device, together with his wife he published in Zeitschrift fur Physik, a paper on velocity modulation of electron beams entitled: "A New Method for Producing Short, Undamped Electromagnetic Waves of High Intensity" which outlined the fundamental working principles of the Klystron tube, a high power microwave oscillator, used to provide the transmitter power in the newly developed radar equipment. Leaving Arsenjeva in Russia, he later moved to the UK to continue development work on the klystron with Standard Telephones and Cables (STC), the UK arm of ITT. The day before England went to war with Germany Heil slipped out of the country returning to Germany to continue his work at Standard Electric Lorentz (SEL), ITT's German arm in Berlin. Heil's klystrons, known as "Heil's Generators", became key components in Germany's World War II radars.

The klystron amplifier works by modulating a high energy electron beam, passing between the cathode and the high voltage anode (typically tens of kiloVolts) of a vacuum tube, by passing the beam first through an input cavity resonator excited by a high/microwave frequency (RF) source. (See diagram of the Klystron). The electrons passing through the resonator are either slowed or accelerated depending on the polarity of the RF input signal at the instant the electron is passing through the cavity causing the electrons to form bunches at the input frequency. This bunching is reinforced as the faster electrons catch up with the slower electrons as the beam transits between the cathode and anode thus increasing the intensity or amplitude of the modulation in a process known as velocity modulation. Before hitting the anode, the electron beam passes through a second, output or "catcher", resonant cavity where the RF energy is absorbed by the cavity and coupled out via a coaxial cable or waveguide.

The klystron can also be configured as an oscillator by coupling the signal from the output cavity back to the input cavity, thus providing positive feedback which creates spontaneous oscillations at the resonant frequency of the cavities.

See also the Travelling Wave Tube (TWT)

After the war Heil's name appeared on an FBI list of Germans accused of war crimes. He was brought to the US by the military and worked at Wright Patterson Air Force Base. Subsequently he formed his own company and carried out intensive research the physiology of the human ear and sound generation by small animals which he applied to the design of sound transducers. His 1973 patent for the Heil Air Motion Transformer (AMT) made him well known to HiFi buffs.

In 1937, American electrical engineers, brothers Russel and Sigurd Varian, also developed a klystron tube based on principles outlined in 1935 by the Heils, but they did not publish their work until 1939. They went on to found Varian Associates in 1948 specialising in microwave components and were the first to move into Stanford Industrial Park, the birthplace of Silicon Valley.

1930's Introduction of Ampoule batteries for use as military fuses.

1936 Carlton Ellis of DuPont was awarded a patent for polyester resin which can be combined with fibreglass to produce a composite.

The curing and manufacturing processes for polyester resin were further improved and refined by the Germans process. During World War II British intelligence agents stole secrets for the resin processes from Germany and turned them over to American firms. American Cyanamid produced the direct forerunner of today's polyester resin in 1942.

1937 The birth of digital technology. American mathematician Claude Elwood Shannon was the one of the first to realise the similarity between electric switching circuits, Boolean logic and binary arithmetic and the first to use these principles as a basis for information processing in his MIT thesis on Vannevar Bush's differential analyser. See also Zuse who developed these ideas independently. Shannon's work on digital technology formed a vital strand to his later work on Information theory.

Shannon, like Zuse, showed that logic devices which are commonly called gates may be implemented with mechanical switches, relays or valves (now transistors).

A computer can perform almost any logic or arithmetic operation using combinations of only three types of gates, called AND, OR, and NOT gates. If an "input" or an "output" is defined as a logic "1" and the absence of an input or output as a logic "0" then:

  • AND gates give an output only if all the inputs to the gate are present.
  • OR gates give an output if any of the inputs to the gate are present.
  • NOT gates give an output if no input to the gate is present. A gate used for this function is also called an inverter.

1937 Eccentric English engineer and visionary Alec Harley Reeves working at ITT in France invented pulse code modulation (PCM) to minimise the effect of noise on transmission systems. Although his system was used for top secret communications during World War II, it needed many more components than conventional analogue circuits and it was not until the availability of integrated circuits that the large scale deployment of digital PCM systems became economically viable.

Electrical noise can be a serious problem with all communications circuits. As a signal progresses down a communications channel it gets weaker and at the same time picks up electrical noise. Each time the signal is amplified to restore its level, the noise is amplified with the signal until the signal may eventually be swamped by the noise. Digital circuits avoid this problem by using a transmitter which samples the analogue signal at high speed (See Shannon above) and converts the amplitude of the signal into a series of pulses, coded so that the pattern of the pulses represents the amplitude of the signal. This process is known as quantising and may be used to derive a simple binary number or some more complex encrypted data code. Noise affects the pulsed or digital signal in exactly the same way distorting the signal, however weak signals are not amplified to restore the signal strength. Instead, using a technique first employed by Henry in 1831, the distorted or noisy pulses are simply used to trigger a new set of clean, high level pulses to replace the weak and dirty signal pulses. The original pulsed waveform is thus regenerated and the noise is left behind. At the receiving end the original analogue signal is reconstituted from the pulses. Because of their noise immunity and amenability to multiplexing and computer controlled data manipulation, digital circuits based on Reeves' work have now almost completely replaced analogue circuits even for the simplest of functions. Standard integrated circuits are available to carry out the analogue to digital (A to D) and digital to analogue (D to A) conversions.

Although a pacifist, Reeves developed a pinpoint bombing system during the war "to minimise civilian casualties". He worked on radar systems, multipexers, fibre optics and acoustic components and was awarded over 100 patents. He also experimented with the paranormal using Geiger counters, pendulums, and electronics in his research and believed he was in regular contact with the long dead Michael Faraday. He claimed to have played in the French Open tennis championships - which were indeed 'open' to anyone who wished to participate. Reeves dedicated his private life to community projects, helping others, encouraging youth and rehabilitating prisoners.

1937 English engineer Robert J. Dippy working in Watson-Watt's radar team at the UK Telecommunications Research Establishment (TRE) conceived the radio navigation system using coordinated transmissions from three or more radio stations to pinpoint the location of a receiver. It relies on the fact that all the points where the time difference between radio signals from two different stations is constant form a hyperbola. The distance of the receiver from the transmitters (the locus of the hyperbola) can be calculated from the time differences from each transmitter. Signals from a second pair of stations determine another set of hyperbolas. The exact position of the receiver is determined by finding the point on the map where the two hyperbolas intersect. Dippy received a patent in 1942 for this invention which was implemented in the Gee navigation system used by the British Bomber Command in World War II. (The name "Gee" or "G" is short for Grid). Dippy's principle of using intersecting radio beams was subsequently used in the LORAN navigation network and is used in the modern GPS (Global Positioning by Satellite) system in which the transmitters are located in orbiting satellites rather than in fixed ground based stations. Like computers, the early navigation systems were large and heavy and housed in equipment racks. Modern navigation receivers are hand held and battery powered.

After working as advisor on the development of LORAN in the USA, Dippy became a Divisional head of research in Australia's Defence Science and Technology Organisation.

1937 Printed circuits were demonstrated by London born British engineer with Hungarian parents John Adolphe Szabadi. In 1938 Szabadi changed his name to John Sargrove by which he is better known since Adolphe wasn't the most popular name in Britain at the time. His circuits were more like thick film integrated circuits than the printed circuit boards (PCBs) we know today. The system did not use etching as with modern PCBs. Instead, with the Sargrove method was an additive, process in which, not just the interconnecting circuit tracks but also the resistors, inductors, capacitors and other components were formed by spraying on to a pre-moulded bakelite panel.

1938 American engineer Hendrick Wade Bode building on Nyquist's work at Bell Labs employs magnitude and phase frequency response plots of a complex function to analyse closed-loop stability in electronic systems. This formed the basis of classical control theory used in the design of stable electronic and other control systems.

1938 Canadian inventor Al Gross invented the Walkiie-Talkie two way mobile radio which was quickly picked up by the military and widely used during the war. In 1948, he pioneered Citizens' Band (CB) radio and in 1949, he invented the telephone pager.

1938 Chemist Otto Hahn and physicist Fritz Strassman from Germany and Lise Meitner from Austria verified the possibility of releasing energy by the phenomenon of nuclear fission, the splitting of the atom, first demonstrated by Rutherford in 1917. They bombarded uranium with neutrons and the uranium nucleus split into two roughly equal halves forming Barium and Krypton with the emission of three neutrons and a large amount of energy, the basis for the chain reaction which gave rise to nuclear power and bombs. From her work in Germany, Meitner knew the nucleus of uranium-235 splits into two lighter nuclei when bombarded by a neutron and that the sum of the masses the particles derived from fission is not equal to the mass of the original nucleus. She speculated with her nephew, Otto Frisch, that the release of energy would be a hundred million times greater than normally released in the chemical reaction between two atoms. She was however not present when Hahn and Strassmann verified this result experimentally since, being Jewish, she was forced to flee to Sweden to escape Nazi persecution when Austria was annexed by the Germans. The results were published by Hahn and Strassmann and Hahn alone was eventually awarded a Nobel Prize for chemistry for this work. Meitner was not credited in the report since Hahn feared the result would be rejected if it were known to be tainted by "Jewish science", - female Jewish science at that. In January 1939 Meitner and Frisch published their hypothesis in a paper entitled Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction in which they coined the term fission and explained the process involved and calculated the energy released.

The German nuclear weapons research programme during World War II was led by Heisenberg and neither Hahn, Strassmann nor Meitner were involved.

1938 Contrary to popular belief, non-stick Teflon was not a product of NASA's space program. It was discovered by accidentally in 1938 by DuPont chemist Dr. Roy J. Plunkett while investigating possible new refrigerants. His lab technician Jack Rebok found an apparently defective cylinder of tetrafluoroethylene gas. Although it was the same weight as full cylinders, no gas emerged when the valve was opened. Rebok suggested sawing it open to investigate and inside, Plunkett discovered that a frozen, compressed sample of tetrafluoroethylene gas had polymerised spontaneously into a white, waxy solid to form poly tetrafluoroethylene (PTFE).

PTFE has a high melting point, is inert to virtually all chemicals and is considered the most slippery material in existence. Now used as extensively an insulator or separator in a wide variety of batteries an other electrical equipment, it remained a military secret until after the end of World War II.

Another secret? - How do they get Teflon to stick to the cookware?

1938 65% of British homes wired for electricity.

1938 German born American engineer Joseph G. Sola invented the Constant Voltage Transformer (CVT). Based on ferroresonant principles it has a capacitor connected across the secondary winding. The voltage on the secondary winding increases as the input voltage increases, however the corresponding increasing flux produces an increase in the leakage reactance of the secondary winding and this approaches a value which resonates with the capacitor connected across it. This causes an increased current which saturates the magnetic circuit thus limiting any further rises in output voltage due to increased input voltage. The output may not be a pure sine wave but usable outputs can be obtained with a swing of +/- 25% in the input voltage. Furthermore, the transformer will absorb short duration spikes and due to the energy storage in the resonant circuit the output will hold up for short power interruptions of half a cycle (10 milliseconds) or more, making it useful for UPS applications.

1938 Swiss born German physicist Walter H. Schottky explained the rectifying behaviour of a metal-semiconductor contact as dependent on a barrier layer at the surface of contact between the two materials which led to the development of practical Schottky diodes. He had been one of the first to point out the existence of electron "holes" in the valence-band structure of semiconductors.

During his lifetime Schottky contributed many theories, designs and inventions including the superheterodyne radio, the tetrode valve and the ribbon microphone which transformed the electronics industry.

1938 German civil engineer Konrad Zuse completed the world's first programmable digital computer, an electromechanical machine, which he called the Z1. Started in 1936, it was built in his parents' apartment and financed completely from his own private funds. It pioneered the use of binary arithmetic and contained almost all of the functions of a modern computer including control unit, memory, micro sequences and floating point arithmetic. Programs were input using holes punched into discarded 35-millimetre movie film rather than paper tape and data was input through a simple four decimal place keyboard. The calculation results were displayed on a panel of light-bulbs. The clock frequency was around one Hertz. Relays can be used to store data since the position of the contacts, closed or open, can be used to represent a one or a zero, but Zuse did not use this solution because relays were very expensive. Instead he devised a mechanical memory system for storing 16 X 22-bit binary numbers in which each memory cell could be addressed by the punched tape or film. For storing data it used small pins which could slide in slots in movable steel plates mounted between sheets of glass which held them together. The pins could move and connect the the plates and their position at either end of the slot was used to store the value 0 or 1. Individual memory units could be stacked on top of one another in a system of layers. In keeping with the German tradition of solid engineering Zuse claimed "These machines had the advantage of being made almost entirely of steel, which made them suitable for mass production".

Zuse was called up for military service in 1939 but was later released from active service, not to work on computers as might be expected, but to work as an aircraft engineer. He continued the development of his ideas in his spare time and, despite the shortages of materials, in 1941 he demonstrated his third machine imaginatively called the Z3. With limited backing from the DVL, the German Aeronautical Research Institute, this time he was able to use 2,600 relays, which were more reliable than his metal plates, to form the memory registers and the arithmetic unit. The memory capacity was increased to 64 words and the clock frequency was increased to 5.33 Hertz. The Z3 is the undisputed, first fully programmable practical working electronic digital computer. It was programmed using punched tape but because of size limitations of the memory, the Z3 did not store the program in the memory. Otherwise it used the basic architecture, patented by Zuse in 1936, and all the components of a modern computer. Credit for defining this concept was later incorrectly attributed to Hungarian born American mathematician John von Neumann.

(In fact the genesis of the so called "von Neumann architecture" arose from the First Draft of a Report on the EDVAC, Eckert and Mauchly's second generation computer which incorporated the lessons learned, and the insights gained, from their experience with their earlier, pioneering ENIAC computer. The "draft" progress report about the development of EDVAC was written in 1946 by von Neumann in which he summarised the ideas of the EDVAC design team. Von Neumann had joined the project as it neared completion and the report was published under his name only and circulated by his colleague and fellow mathematician Herman Goldstine much to the annoyance of Eckert and Mauchly and other team members who pointed out that many of the ideas predated Von Neumann's involvement in the project.)

Zuse had been helped during the construction of the Z1 machine by fellow engineer and inventor Helmut Schreyer who later suggested to Zuse that he should replace the relays in his computers by electronic valves which were over 1000 times faster. Zuse liked the idea and ran with it.

After the success of the Z3 in 1941, the government at last took notice of Zuse's work but when he proposed a faster computer based on electronic valves, it was rejected on the grounds that the Germans were so close to winning the War that further research effort would take too long and was therefore not necessary. (Hitler expected the War to be over in two years and so had banned long term projects.)

In the early aftermath of the war West Germany was prohibited from developing electronic equipment, materials were even scarcer than before and electrical power was only available intermittently. His latest computer the Z4 had also been damaged in the Berlin air raids but Zuse had managed to rescue it and after many difficulties he was eventually able to restart its development in Switzerland. Completed in 1950, the Z4 was the first computer in the world to be sold to a commercial customer, beating the Ferranti Mark I in the UK by five months and the UNIVAC I in the USA by ten months.

Between 1942 and 1946 Zuse also developed Plankalkül (German, "Plan Calculus") the world's first high level programming language but did not publish at the time. It included assignment statements, subroutines, conditional statements, iteration, floating point arithmetic, arrays, hierarchical record structures, assertions, exception handling, and other advanced features such as goal-directed execution. Intended as an engineering tool for performing calculations on structures, Zuse also used Plankalkül to write a program for playing chess. At that time the concept of software was unheard and surprisingly he did not start with machine oriented assembly language programming but immediately set out to develop the more complex user oriented language. Plankalkül was the first modern programming language at any level above manual toggle switching or raw machine code. It was finally published in 1972 and the first compiler for it was implemented in 2000 by the Free University of Berlin, five years after Zuse's death.

Until 1950 Zuse lived in complete isolation from the world outside Germany particularly during the war years when he remained in Berlin where his first three computers and his workshop were destroyed by allied bombing raids. He had little knowledge of computer developments elsewhere and his work was likewise almost unknown outside of Germany, although IBM obtained an option on his patents in 1946. He was not successful as a businessman and his company was sold to Siemens in 1967. Besides his engineering talents Zuse was also an accomplished artist who sold his paintings during his early years to fund his studies and at the end of the war sold woodcuts to American troops in order to buy food. In retirement he returned to painting as a hobby.

There have been many claimants to the title of The First Computer. For the record, here are the dates when some other early programmable computers became fully operational:

  • 1941 - Zuse Z3 (Germany) See above.
  • 1942 - ABC (Unfinished) (USA) The Atanasoff-Berry Computer, built by John Vincent Atanasoff and his graduate student Clifford Berry at Iowa State University. It used 311 vacuum tubes (valves) to perform binary arithmetic but it was not a stored program machine nor was it fully programmable but program changes could be input using switches. It was abandoned before it was completed when Atanasoff left to do military service. At the time, neither Atanasoff nor the Iowa University thought it necessary to patent any of the innovative concepts used in the ABC.
  • 1943 - Colossus (UK) built by Post Office engineer Thomas (Tommy) Harold Flowers, and mathematicians Maxwell (Max) Herman Alexander Newman and Alan Mathison Turing at Bletchley Park was the first all-electronic calculating machine. Colossus was used during WWII to break German codes and was the first to work on symbols and logical operators, not just numbers and arithmetic, and used 1,500 vacuum tubes to perform boolean operations. Turing's role was in developing the code breaking procedures and he was not involved in the design of the machine which was done by Flowers. The machine was programmed using switches and cables in a patch panel which needed rewiring to implement program changes. Data was entered using punched tape. Ten Colossi were built and used in great secrecy and no attempt was ever made to commercialise them. At the end of the war Winston Churchill ordered eight of them to be smashed "into pieces no bigger than a man's hand" and all the drawings to be burned. The two remaining machines were sent to GCHG the UK government's top secret communications centre. It was not until 1970 that existence of the Colossus was revealed publicly as the result of the USA's Freedom of Information Act. (The US government had been given details of Colossus during the war as part payment for US assistance to the UK's war effort.)
  • 1944 - Harvard Mark 1 (AKA IBM ASCC) (USA) Built by IBM's Howard Aiken. An automatic digital sequence-controlled computer, based on relays and rotary switches. It used decimal arithmetic and programs were entered using punched tape.
  • 1946 - ENIAC (USA) Electrical Numerical Integrator and Calculator, built by John Presper Eckert and his student John W. Mauchly at the University of Pennsylvania. It used 18,000 vacuum tubes and consumed almost 200 kilowatts of electrical power. It was a single purpose machine designed to plot missile trajectories. Funding for the project was secured by Herman Heine Goldstine, an ordnance mathematician at the U.S. Ballistic Research Laboratory, who teamed up with Mauchly. Calculations used decimal rather than binary arithmetic and it was not a stored program machine. Programs were entered manually using switches and cable connections in an external patch board and were modified by rewiring. The forerunner of the UNIVAC (Universal Automatic Computer) machine launched by Remington Rand in 1951 after they had purchased Eckert and Mauchly's company, the ENIAC used design concepts Mauchly had copied from Atanasoff's ABC machine for which Atanasoff received neither credit nor recognition. In 1973 when Sperry Rand tried to extract royalties for the use of its ENIAC computer patent they were challenged in court by Honeywell and the court voided Sperry Rand's patent declaring it to be a derivative of Atanasoff's inventions.
  • 1948 - Manchester Mark 1 (AKA "Baby") (UK) Built by Max H.A. Newman, who had worked on Turing's Colossus machine, and Freddie Calland Williams with software written by Tom Kilburn. The first computer with a true stored-program capability and von Neumann architecture, it used the persistence of the image on the phosphor screen of a cathode ray tube (CRT) for data storage and binary arithmetic for processing. The Manchester Baby was the basis for the Ferranti Mark 1 introduced in 1951, one of the first commercially available computers.
  • 1949 - EDSAC (UK) Electronic Delay Storage Automatic Computer, built by Maurice V. Wilkes at Cambridge. A true general purpose stored program machine using binary arithmetic. Not to be confused with the Eckert and Mauchly's EDVAC (See below)Electronic Discrete Variable Automatic Computer which did not become fully operational until 1952, it was the first to use a mercury acoustic delay line for data storage.
  • 1949 - LEO (UK) Lyons Electronic Office, the first business computer, derived from EDSAC and developed by J.Lyons and Company, a British catering firm.
  • 1952 - Eckert and Mauchly's second generation machine the EDVAC Electronic Discrete Variable Automatic Computer became fully operational. Their earlier ENIAC computer had been designed with the prime purpose of calculating artillery firing trajectory tables for the US Army. As its development progressed, the pair had identified numerous opportunities for improvements but, because of wartime exigencies, a design freeze was imposed to get ENIAC into service as soon as possible and they were not able to incorporate all of their ideas into the machine. EDVAC provided the opportunity to develop their ideas further. Design started in 1946 with an initial study group which included members of the ENIAC team, Herman Goldstine and another mathematician, Arthur Walter Burks. They were joined later in a consulting role by John von Neumann a mathematician who worked on the Manhattan Project. One of EDVAC's key ideas was that the computer could store programs for different applications in its electronic memory rather than programming the computer for each new application by using mechanical switches and patch cables as in the ENIAC. The EDVAC was also the first to use a mercury acoustic delay line for data storage.

Echoing Babbage's experience, with four out of the first eight modern computers, UK innovation once more was not translated into commercial success.

Computers have become essential tools in almost every aspect of engineering and business management and their modern counterparts, microprocessors are now key components in battery management systems.

1939 The German company I.G. Farbenindustrie filed a patent for polyepoxide (epoxy). Benefiting from German technology epoxy resins were made available to the consumer market almost four years later by an American manufacturer. They have very strong adhesive properties being one of the few materials which can make effective joints with metal. They are dimensionally stable and have similar expansion rates to metals. When combined with fibreglass they can produce an extremely strong composite materials, known as Glass Reinforced Epoxy (GRE) , strong enough for use as aircraft components.

Because of epoxy's chemical resistance and excellent electrical insulation properties, electrical parts such as batteries, relays, coils, and transformers are insulated with epoxy.

See also polyester resins.

1939 Following speculation by Arthur Eddington, nuclear physicist Hans Bethe, a Jewish refugee from Germany, working in the USA explained in quantitative terms how the energy in the Sun and the stars could be generated by nuclear fusion. It involved a series of fusion reactions in which Hydrogen atoms were first transformed into Hydrogen isotopes which in turn were transformed into Helium with the release of large amounts of energy.

Ever since then attempts have been made to duplicate the final stage of this fusion process on Earth in the quest for cheaper, safer nuclear power generation.

Bethe presented his theory in a paper entitled "Energy Production in Stars" which won him the Nobel prize for Physics in 1968.

1939 Almost two thirds of British households have electric lighting.

1940 John Turton Randall and Henry Albert Howard Boot working at the Nuffield Laboratory Physics Department of Birmingham University developed the first practical cavity magnetron, a high power microwave transmitter valve (vacuum tube) which was an essential component in wartime Radar transmitters. It could generate 1000 times the power of any other existing microwave generator at the time. Now an essential component in microwave ovens.

The magnetron had been invented by Hull in 1920 but its low power output limited its possible applications. Randall and Boot dramatically improved on this by using resonant cavities to reinforce the oscillations generated by the basic cathode - anode structure of the device. Instead of using a thin walled tube for the anode, the anode is constructed from a large cylindrical block of copper. See diagram of a Resonant Cavity Magnetron. A cylindrical hole bored through through the centre of the anode block forms the main interaction space between the electrodes. Spaced equally around this central chamber, a number of cylindrical cavities are bored into the block, parallel to the main chamber. A narrow slot along the length of each of these cavities connects them to the central chamber. At the critical magnetic field, the electrons sweep past these apertures inducing a resonant, high-frequency radio field in the cavity, which in turn causes the passing electrons to bunch into groups. The bunches are reinforced as the electrons circulate around the central chamber passing each resonant cavity in turn in a similar way to the velocity modulation on which the travelling wave tube (TWT) and the klystron depend. A portion of the field is extracted with a short antenna protruding into one of the resonant cavities and connected to a waveguide or coaxial cable and fed to the RF load.

1940 Jewish physicists, Austrian born Otto Robert Frisch and German born Rudolf Peierls, both refugees from the Nazis and working at Birmingham University designed the first theoretical mechanism for the detonation of an atomic bomb. It was published in a paper, known as the Frisch-Peierls Memorandum, describing the processes and the materials required to produce an atomic explosion, in a practical sized device, triggered by conventional explosives. It also predicted the destructive power of the explosion as well as the resulting radioactive fallout. The information was passed to the Americans as part of the Tizard Mission the same year and was one of the key events leading to the setting up of the Manhattan Project in 1942 and the UK participation in it.

In 1939, Frisch had published with Lise Meitner the explanation of nuclear fission and quantified the energy released and described its potential for a chain reaction. Peierls' prior work mainly involved the use of quantum theory to explain semiconductor behaviour.

1940 During the UK's darkest days in the World War II, the British government sent a Technical and Scientific Mission, led by chemist Henry Tizard, to the USA, which was still neutral at the time, to seek cooperation and resources desperately needed to develop UK military technology as well as access to US technology. The UK contributed details of Randall and Boot's cavity magnetron - (See Loomis), Frank Whittle's jet engine, Robert Dippy's Gee radio navigation system and a summary of the UK's atomic research outlined in the Frisch-Peierls Memorandum which proved the feasibility of an airborne atomic bomb supported by the relevant calculations of the size of the critical mass required (it was thought at the time that the bomb would be so big that it could only be taken to its target by ship). There were also designs for rockets, superchargers, gyroscopic gun-sights, submarine detection devices, self-sealing fuel tanks and plastic explosives.

The Tizard Mission was carried out despite strong reservations by Winston Churchill and Robert Watson-Watt, the radar pioneer, and although it was hailed as a success, the UK gave away technology that had immense commercial value after the war. In return it got help particularly with radar, a stronger Anglo-American alliance at a very critical time and a seat at the table of nuclear powers.

While Tizard was away, his job was abolished.

1940 Development started on LORAN, the LOng RAnge Navigation system which was one of the Rad Lab's first projects and its only major non microwave project. It was a development of the British Gee system whose design details were provided to the US as part of the Tizard Mission. The Gee system was designed for short range bombing missions and transmitted in the frequency range 20 to 85 MHz (15 to 3.5 meters wavelength) achieving a range of 400 miles. LORAN used the same hyperbolic grid system as Gee but was designed for long range radio navigation over the oceans. It used a frequency range of 1850 to 1950 kHz (150 to 160 metres wavelength) which enabled a range of 1200 miles but with lower accuracy, particularly at the range extreme which depends on the ground wave effect and ionospheric reflection. (Longer waves are bent more around the curvature of the Earth due to the ground wave effect which tends to slow the radiation wave front near the ground and by the reflection from the ionosphere resulting in greater propagation distances.)

The project was led by John Robinson Pierce of Bell Labs assisted for eight months by Robert Dippy, the designer of the Gee system, and was supervised personally by the Rad Lab founder Alfred Loomis himself.

The system went live in 1943.

1941 Silver oxide- Zinc (Mercury free) primary cells developed by French professor Henri André using cellophane as a semi permeable membrane separator which impeded the formation of dendrites which caused short circuits.

1941 Bell Labs researcher Russell S. Ohl discovered that semiconductors could be "doped" with small amounts of foreign atoms to create interesting new properties. He discovered the principles of the P-N junction (with some hints from Walter Brattain) and invented the first Silicon solar cell, a P-N junction that produced 0.5 volts when exposed to light. Ohl's invention of the semiconductor junction and his explanation of its working principles laid the foundations on which the invention of the transistor was based. Unfortunately, Ohl's essential contribution has almost been forgotten.

1941 American inventor B.N. Adams filed for a patent on the water activated battery. Working at home, he had developed the battery for military, marine and emergency us and he demonstrated it to the US Army and Navy. Unfortunately the US Army Signal Corps declared the invention to be unworkable. Nevertheless Adams was awarded a patent in 1943. At the height of World War II however the US Signal Corps decided the idea was indeed feasible after all and the government entered into procurement contracts with several battery making companies without informing Adams. He subsequently discovered in 1955 that his invention had been in use for some time by the US government who by then claimed the idea lacked novelty and was obvious and was therefore not patentable. In 1966 Adams sued the US government and the Supreme Court found in his favour and his 1943 patent was upheld.

1941 Patent granted to American inventor Harold Ransburg for the electrostatic spray coating process in which the paint is electrostatically charged and the surface to be painted is grounded. An idea first proposed by Nollet in 1750. Because of the electrostatic attraction between the positively charged paint and the grounded body the majority of the paint reaches its target resulting in major savings.

1941 Thick Film Circuits developed by Centralab division of Globe-Union Inc in the USA - An innovative use of screen printing technology patented in 1907. They used resistive inks and silver paste printed on ceramic substrates to form printed resistors, capacitors, links and other components in miniature circuits used in proximity fuses. Similar printing processes are used today to manufacture thin film batteries.

1942 Building on Chadwick's work, the first controlled, self-sustaining nuclear chain reaction was achieved by a team led by Italian Enrico Fermi in an atomic pile set up in a squash court at the University of Chicago. During nuclear fission, a fast-moving neutron splits an atom's nucleus, which results in the release of energy and additional neutrons. These ejected neutrons can split further nuclei, which release more neutrons to split yet more nuclei, and so on creating a self-sustaining chain reaction. If this chain reaction goes too fast, it becomes an atomic explosion, but under control it could produce a steady flow of energy. If the chain reaction starts with uranium, it also creates a byproduct, plutonium, a better fuel for a nuclear weapons. Fermi found that cadmium would absorb neutrons. If the chain reaction speeded up, cadmium rods could be inserted into the pile to slow the reaction down and could be removed to accelerate it again.

Fermi's nuclear reactor did not have any cooling system or radiation shield and it has been said that, if the cadmium control rods had failed or if they had got their calculations wrong, half of Chicago could have been blown up. This risk however is overstated. The safety of this initial pile was not just dependent on the cadmium control rods. The reactor had just enough of the scarce and expensive new materials to achieve critical mass and Fermi's construction was such that any overheating was designed to cause deformation or disintegration of the reactor pile, destroying the critical mass concentration, before enough fissions have occurred to build up enough energy to cause an explosion. Nevertheless, as a precaution physicist Norman Hilberry stood poised with an axe during the start-up, ready to cut a rope and release more cadmium control rods that would stop the reaction in an emergency. If all else failed, a three-man "suicide squad" of physicists stood ready to drench the pile with cadmium sulphate.

This event marked the birth of the nuclear power industry and also the atom bomb.

See more about Nuclear Power

1942 American chemist Harry Coover working on materials for optically clear gun sights accidentally discovered cyanoacrylate a fast acting transparent adhesive. It proved too sticky for the job in hand and its true potential was not realised until 1958 when it was marketed as Superglue. Now used extensively in industry for gluing together small sub-assemblies such as battery packs.

Superglue's ability to stick skin together was turned from a problem into a benefit during the Vietnam War saving the lives of countless soldiers when it was used in to seal battlefield wounds before the injured could be transported to a hospital.

1942 American chemists William Edward Hanford and Donald Fletcher Holmes working at du Pont de Nemours invented the process for making the multipurpose material polyurethane. Now extensively used as a foam insulating material in a wide range of applications.

1942 Glamorous Hollywood movie star Hedy Lamarr, born Hedwig Kiesler Markey in Vienna, and American composer and concert pianist George Antheil, were granted a U.S. patent for a secret communication system which was the first to use frequency hopping as a method of avoiding jamming (deliberate interference) by the enemy. Constant switching between different transmission frequencies by the communicating parties prevents the jammer from knowing which frequency to attack. Their initial application was a guidance system for torpedoes which was offered to the US Navy.

The mechanisms used to control the frequency hopping were two synchronised paper rolls, similar to those used to program pianolas (player pianos) at the time, one in the transmitter and one in the receiver. The communications frequency was determined by capacitors in the tuning circuits of the transmitters and receivers which each contained a bank of capacitors from which individual capacitors could be selected. The appropriate capacitors from the bank were connected to the tuning circuits for controlled intervals by switches turned on and off in a sequence determined by punched holes in the pianola rolls giving a possible 88 distinct frequencies.

Once the communications link was established, guidance was by conventional remote control circuits.

How did such an unlikely pair come to invent such a product?

Hedy had been married in 1933 at the age of 19 to Fritz Mandl an extremely wealthy and influential Austrian international arms dealer. Well educated and beautiful (See Hedy) she was already famous in Austria for the film "Ecstasy", released earlier in the year in which she had appeared naked, (the world's first). Mandl installed her as his trophy wife in his substantial estate where she was expected to play the perfect hostess to the high level government delegations who were invited to discuss arms supplies in his luxurious surroundings. Like an exotic bird in a gilded cage, Mandl demanded her presence at all times, even during technical discussions and business negotiations, so she was most likely aware of some of the technical issues involved. After four years in Mandl's clutches she escaped, making her way to America where she successfully took up acting once more and where in 1941 she met Antheil by chance.

George had spent over ten years in Paris and was an acquaintance of many of the great artists, writers and composers of the day. His early compositions were outrageously avant garde and and among the vast array of instruments called for in his Fourth Symphony the "Ballet Mechanique" were seven electric bells, a siren, three aeroplane propellers, gongs, two pianos and sixteen synchronised pianolas.(See George)

Hedy and George both spoke German. She was born into a Jewish family in Austria, George's family were Polish immigrants in the USA and in the early days of the Second World War they both wanted to do their bit for the war effort before the U.S. entered the war. Between them they had only superficial knowledge of the technologies involved yet they pioneered what was to become an essential component of secure military communications and eventually a subsystem of modern spread spectrum and cellular communications.

Unfortunately they got very little credit for their ideas. They had no credibility as engineers, Hedy was an alien and their loyalties were suspect and besides the U.S. Navy's torpedoes were powered by compressed air, while the German torpedoes were electrically driven. Their patent eventually expired in 1957 without earning them any revenue, just about the time their ideas were picked up and exploited by Sylvania and others for "classified" military applications. Adoption of the technology for commercial applications was hampered by the reluctance of the U.S. Federal Communications Commission (FCC) to allocate sufficient frequency spectrum for its use.

Spread Spectrum Applications

  • Security
  • Hedy and George's system solved the security problem by spreading the signal to be transmitted over multiple frequency carriers and frequency hopping between them, but it required a much wider system bandwidth for the communications.

    But just as Hertz did not envisage the use of radio waves for communications and Rutherford did not foresee the possibility of generating nuclear power from nuclear fission, they did not anticipate two more important potential applications of their invention, which are key to modern communications systems, which were made possible by its broadband signal channels.

  • Multiplexing
  • The first alternative application seems fairly obvious and could have been implemented using their pianola rolls. By using more than one, independent, code sequence provided by more pairs of pianola rolls, they could have transmitted more than one simultaneous message over the broadband link. This is a very simple example of a code division multiple access (CDMA) system used for multiplexing. Problems could possibly occur if the multiplexing codes happened to result in two messages at some point being assigned the same frequency, but this could be avoided by careful programming of the code sequences or overcome, if it did occur, by blocking the transmission for the corresponding interval and resending the message during the next interval

  • Improved noise performance
  • They can be forgiven for not anticipating the second application. In 1948 Shannon published his mathematical theory of communications in which he outlined the possible noise / bandwidth tradeoff in a communications channel. He showed that system noise performance can be improved by spreading the signal across a greater bandwidth for transmission, a technique which is also used in modern communications systems.

  • Correlation detection and Filter matching
  • In the early 1950s, electronic implementations of spread spectrum technology were mostly for military applications, many of which were classified as secret at the time. Radar systems which need to extract very low level signals reflected by the target from high ambient thermal noise and clutter (extraneous signals or interference) are such examples. The solution was to modulate the transmitted pulse with a pseudorandom code sequence. The reflected signal was fed into a correlation detector together with a delayed reference copy of the the same pseudorandom code. The correlation detector gives an output only when the modulation pattern of the its two inputs are precisely matched or correlated, even in the presence of noise levels which may be greater than the signal level, otherwise the output is zero or just noise. The delay between the reference signal and the reflected signal is varied until the correlator indicates a match, at which point the delay corresponds to the two way transmission time of the signal between the transmitter and the target, from which radar range can be calculated.

    Another way of thinking of the correlation process is to consider it as filter matching. Using the piano roll analogy, the signal is only transmitted when there are holes in the transmitter piano roll. A matching piano roll, delayed from the transmitter roll, is used in the receiver and the output is only considered valid if there is a received signal corresponding to every hole (or most of them) in the roll otherwise the output is ignored.

1942 Austrian-born engineer and physicist Rudolf Kompfner working at the Nuffield Laboratory Physics Department of Birmingham University (the birthplace of the cavity magnetron) first sketched out the design for the Travelling Wave Tube (TWT) amplifier which he built early the following year. Similar in some ways to the klystron it was a radio frequency (RF) microwave amplifying tube but with a very wide bandwidth, and was the first to be capable of amplifying high capacity multiplexed telephone voice channels or broadband data and TV channels. It was thus suitable for use in microwave repeater stations enabling the expansion of the telephone network and was later used in onboard satellite communications repeaters.

As in the klystron, the TWT modulates an electron beam travelling between the cathode and the high voltage anode of a vacuum tube but it does not use resonant cavities to launch and capture the microwave signal since, by their very nature, resonant cavities limit the bandwidth of the signal. Instead the TWT RF input signal is coupled to a long narrow helical wire coil inside the tube about 30 cms (1 foot) or more long which forms an RF circuit stretching the length of the tube but not connected to the electrodes. (See diagram of the Travelling Wave Tube). The tube itself is contained within in a cylindrical magnet which maintains the electrons focused in a narrow beam travelling along the centre line of the helix. A directional coupler induces the signal current into the helical coil at the cathode end and another coupler extracts the signal at the anode end.

The helical RF circuit acts as a delay line, in which the RF signal travels at near the same speed along the tube as the electron beam. The electromagnetic field due to the RF signal in the helical coil interacts with the electron beam, causing bunching of the electrons as in the klystron, and the electromagnetic field due to the beam current then induces more current back into the RF circuit thus reinforcing the signal current as it passes along the tube in a process known as velocity modulation. At the output end of the helix, the amplified RF signal is extracted by the second directional coupler.

Waves reflected from the output end of the delay line are prevented from traveling back towards the cathode by attenuators placed along the RF circuit.

The TWT was subsequently refined by Kompfner working with John Pierce and Lester M. Field at Bell Labs.

In 1962, the first communications satellite, Telstar 1, was launched with a 4 Watt, 4 GHz TWT amplifier used in the transponder to transmit the first live television signals across the Atlantic.

1943 The printed circuit board was patented in the UK by Austrian born Jewish refugee Paul Eisler, the acknowledged father and publiciser of the PCB. Most of Eisler's patents were for a subtractive process whereby circuit tracks were made by etching copper foil which has been bonded to an insulating substrate. Like the plug, this simple invention was late in arriving - only four years before the much more complex transistor. There had been many proposed designs for PCBs over the previous 40 years, using a wide range of different processes by Hanson, Berry, Schoop, Ducas, Parolini, Seymour, Franz, Sargrove, Centralab and others, but Eisler's processes were more practical and were quickly adopted by the US Army. Despite this, it was not until the 1950's that the use of PCBs finally took off, helped no doubt by the advent of the transistor.

Some of the processes involved in Eisler's patents were borrowed from the printing industry and some of the patents mentioned above were cited by Eisler in his patent applications and although the use of PCBs was virtually unknown at the time Eisler's patents were granted, they were challenged by the Bendix Corporation in the USA and overthrown in 1963 on the grounds of prior art. Eisler died in 1995 a bitter man.

Eisler held patents for a number of other popular developments, mostly involving heated films, including the rear windscreen heater, heated wallpaper, food warmers for fish fingers and other foods, heated clothes (John Logie Baird got there first with his 1918 patent for damp-proof socks) and also a battery powered pizza warmer for take out pizzas.

It was another six years before dip soldering was invented.

1944 Germany's Terror Weapons, the V-1 Flying Bomb and V-2 Missile were deployed in combat for the first time. The V-1 was essentially a pilotless aeroplane which was championed by the Luftwaffe whereas the V-2 rocket was more like a guided artillery shell and this was the weapon preferred by the army.

There was little crossover between V-1 and V-2 programmes which were developed in parallel and Hitler was not particularly enthusiastic about the rocket program believing that the weapon was simply a more expensive artillery shell with a longer range.

In 1942 the German V-1 Flying Bomb, the precursor of the cruise missile achieved its first successful powered flight in December 3rd 1942, two months after the first V-2 flight. Originally designated as the Fieseler Fi 103 it was renamed the V-1 from the German Vergeltungswaffe 1 - "Vengeance or Retaliation Weapon 1". Basically a pilotless aeroplane it was powered by a pulse jet, air breathing engine. (See image and cutout diagram of the V-1 Flying Bomb). It was only only 7.73 m (25.4 ft) long with a wingspan of 5.33m (17.5 ft) and had a range of 250 km (160 miles) and carried a payload of 850 kg (1,900 lb) of explosives, flying at an altitude of between 600 to 900 m (2,000 to 3,000 ft) with a speed of 640 km/h (400 mph).

The first V-1 was launched towards London on 13 June 1944, one week after the successful D-Day landings in France, and landed in Hackney killing 6 people.

  • The Designers
  • The idea of a flying bomb was first proposed to the German Luftwaffe in 1935 by Paul Schmidt, a pioneer of pulse jet engines but his proposition was rejected. Four years later, at the start of World War II, the idea was proposed once more, this time by Fritz Gosslau who had already developed a remote controlled surveillance aircraft and had been working independently on pulse jet engines with Manfred Christian at the Argus Motor Works in Berlin. This time the proposal met with support but no commitment from the Luftwaffe who helpfully suggested teaming up with Paul Schmidt. Subsequently the team produced a more practical engine in 1940.

    Argus needed help in designing the airframe to carry their engine and in 1942 Robert Lüsser, previously chief designer and technical director at Heinkel, now working for the Fieseler company, took charge of the overall project and produced a preliminary design for the complete flying bomb.

    They still needed a guidance system and this was subcontracted to the Askania company in Berlin where engineers Guido Wünch, Herman Pöschl and Kurt Wilde designed the necessary guidance and control system.

    Overall project control was the responsibility of Berthold Wöhle.

  • The Design
  • Since the missile was expendable, it had to be very inexpensive to make and should use cheap readily available materials and low grade fuel. It was however pushing the bounds of known technology and thus subject to numerous changes and improvements as well as trials of alternative variants during both the development period and its deployment. The following is a description of the main components.

    • The Pulse Jet Engine
    • The pulse jet engine was beautifully simple. Apart from the input flap valves controlling the air supply, it had no moving parts, not even a fuel pump. It consisted of a long stovepipe or jet pipe, open at one end and covered at the other by a grid of 126 very thin, double leaved, spring steel non-return flap valves or shutters. (See Diagram of the Pulse Jet Engine). The fuel was regular gasoline/petrol and a compressed air supply to the fuel tank at a pressure of 100 psi pumped the fuel into the motor. Inside the pipe and close to the closed end was an array of 9 jets which delivered a constant spray of fuel into the pipe. To start the engine and keep it operating while stationary on the starting ramp, compressed air was pumped through 3 nozzles into the pipe and a standard spark plug provided the ignition of the fuel air mixture. Once the engine was in motion, ignition was self sustaining and the spark plug and external compressed air supply were no longer needed since the air supply was drawn into the pipe through the flap valves by the motion of the engine through the air.

      The combustion process was also very simple. The ignition of the fuel air-mixture caused an explosion, or rapid expansion of burning gas. The increased pressure of the expanding gas in the pipe slammed the spring flap valves closed and the high pressure burning gas was ejected from the open end of the pipe in a jet stream thus providing the reactive thrust to drive the pipe forwards (towards the closed end). As the exhaust gas left the pipe, the internal pressure in the pipe would drop and the external air pressure on the flap valves, due to the motion of the pipe through the air, would exceed the gas pressure in the pipe. The resulting differential pressure, assisted by the valve springs, caused the valves to open allowing a new charge of air to enter the pipe. The spark plug was no longer needed for ignition because enough of the previous charge of burning gas remained in the pipe to ignite the new fuel-air mixture. This combustion cycle, or power pulse, was repeated at around 47 times per second which was the resonant frequency of the pipe and gave the engine its characteristic buzzing sound and hence the missile's nickname, the Buzz Bomb or Doodlebug.

      The ignition shutter system was vulnerable to failure because of the severe vibration of the engine but it was not intended to last beyond the V-1's normal operational flight life of one hour maximum. It took only 22 minutes flight time to cover the 225 kilometres (140 miles) between the launch sites at Pas de Calais in France and its targets in London.

      Because the engine power depends on the air pressure, generated by the speed of the jet pipe through the atmosphere, to drive air into the engine, it delivers very little power at speeds below 240 kph (150 mph) and needs an external power boost from a catapult to give the missile enough speed and hence power to get it off the ground. Once airborne the engine could deliver a thrust of 310 kg (683 lbs) flying at 700 kph (435 mph) at an altitude of 1000 m (3280 ft).

    • The Airframe
    • Designed by Lüsser, the airframe was originally constructed almost entirely of inexpensive, welded sheet steel. The pulse jet was mounted above the fuselage which housed the magnetic compass, the warhead, the fuel tank which was integral with the fuselage, two compressed air tanks, a battery, three guidance gyroscopes and a radio transmitter.(See Cutaway diagram of the V-1). To avoid interference with the magnetic compass, the nose of the fuselage was constructed from aluminium, which is non-magnetic, instead of the sheet steel used for the rest of the plane.

      Because the wings were very small, the missile had a very high stall speed of around 300 kph (190 mph). This meant that its take-off speed was correspondingly very high and was a second reason why power assisted launching was needed to accelerate it to a velocity greater than its stall speed.

      To save cost and weight, no ailerons were provided on the wings and the only control surfaces were the elevators and the rudder in the tail.

      The bomb obviously did not need any landing gear.

    • Internal Power
    • On-board power was mainly supplied by means of compressed air stored at over 2000 psi (150 atmospheres) in two large spherical tanks constructed with an internal shell of welded mild-steel sheet, tightly bound over with steel wire to contain the high pressure. Compressed air, supplied via pressure reduction valves, was used to spin the gyroscopes to operate the pneumatic servos driving the rudder and the elevators and for providing the pressure in the fuel tank to pump the fuel into the engine.

      Two 30 Volt batteries supplied electrical power to various relays, sensors and actuators as well as the radio if it was installed.

    • The Guidance System or Autopilot
    • The bomb was directed to its target from launching ramps precisely oriented towards the target. Once airborne, it was kept on track by means of an ingenious guidance system which relied on a magnetic compass to monitor the heading, gyroscopes for stability and a barometric altimeter for altitude control.

      The master gyroscope was a displacement gyro which detected any deviations from the pre-set flight path. It provided error signals which were used in feedback control systems to move the control surfaces of the elevators and the rudder by means of pneumatic servos to minimise the error. The gyro was mounted in a gimbals with its axis inclined at 20 degrees above the horizon making it sensitive to roll as well as pitch and yaw movements. (See more about Gyroscopes and Guidance)

      Drift of the master gyroscope was corrected by the magnetic compass which provided a reference heading. The compass was housed on vibration damping springs contained within a pair of non-magnetic, mating wooden hemispheres.

      Pitch and yaw were controlled by two spring retained, rate gyros damped by dashpots mounted at 90 degrees to the fuselage centre line. As with the master gyro, error signals from the rate gyros caused pneumatic servos to move the elevator and rudder control surfaces so as to minimise the errors. The gyroscope which controlled the elevators was sensitive to pitch only and was mounted on the vertical axis and the rudder gyro which was sensitive to yaw only was mounted on the horizontal axis. Changes in the missile's attitude caused precession in the corresponding rate gyro in proportion to the rate of change of direction. Differential pneumatic signals from the rate gyros were mixed with the signals from the displacement gyro to provide stability by damping any oscillations and preventing the control surfaces from over-shooting.

      Because the plane had no ailerons, roll compensation was provided by the rudder. Since the axis of the master gyro is elevated by 20 degrees to the horizontal in a vertical plane, a roll will cause the tilted gyro axis to move left or right in the direction of the roll and this will appear to the auto-pilot as a yaw. Hence if the left wing should drop, it uses the rudder to steer to the right resulting in a higher velocity of air over the left wing, thus raising it to the normal position. This interaction meant that rudder control alone was sufficient for steering and no banking mechanism was needed.

      Altitude control was provided by error signals from an aneroid barometer capsule which expands with a decrease in ambient air pressure (or increase in altitude). A pneumatic servo caused deviations from the desired altitude to tilt the gimbals of the displacement gyro. The resulting error signal was used to control the pitch of the bomb causing it to rise or fall to its planned altitude.

      A small 2 bladed, windmill propeller on the nose of the bomb drove a counter which determined the distance travelled. When the target area was reached the counter triggered a mechanism to shut off the fuel supply to the engine causing the bomb to dive silently onto its target.

    • The Launching System
    • Ground-launched V-1s were propelled up launch "ski" ramps 42m to 48m (138 to 158 ft) long inclined at 6 degrees by a steam piston hooked onto the fuselage. To minimise detection by the enemy, the ramps were built very short and, since the stall speed of the bomb was so high and its low speed power so low, it needed a massive acceleration from an external source, in the short distance available, for it to reach take off speed. This assistance was provided by a steam piston designed by Hellmuth Walter, which used a hypergolic (self igniting) mixture of hydrogen peroxide and an aqueous solution of calcium, sodium or potassium permanganates to create vast quantities of steam which drove the the piston forwards at high speed accelerating the missile to its take-off speed of 395 kph (245 mph)

      To avoid the use of ramps, some V-1s were air launched from two-engined Heinkel He-lll bombers to achieve the necessary high launch speed. This was acceptable for test purposes and for manned versions since the pilots could not tolerate the excessive g forces experienced by a 'ski' launch, but it was not particularly practical for operational purposes because the difficulty of determining the precise location reference coordinates for setting the bomb's guidance system led to wide inaccuracies in targeting.

    • Accuracy
    • Unlike the V-2 rocket guidance, the V-1 guidance system was active over the bomb's full trajectory until it was over its target.This gave it superior accuracy to the V-2. Nevertheless, despite its sophisticated guidance system the V-1's (CEP) Circular Error Probability, (defined as the radius of a circle, centred about the mean, whose boundary is expected to include the landing points of 50% of all of the missiles launched) was 13 kilometres (8 miles). This means that the V-1 was incapable of hitting specific targets and caused indiscriminate damage to the civilian population.

    • Development and Production
    • The V-1 was developed by the Luftwaffe at the Army Research Centre at Peenemünde on Germany's Baltic coast.

      Manufacturing of the major assemblies was initially carried out in the Fieseler and Volkswagen factories but after these facilities were bombed by the RAF in August 1943, production was transferred to the less vulnerable, but notorious, underground Mittelwerk plant near Nordhausen where it was carried out by slave labour from the nearby Mittelbau-Dora concentration camp.

    • Variants
    • Because of wartime shortages of key materials, in production, plywood was substituted for constructing the wings. For similar reasons a variety of explosives were used in the warhead.

      Radio controlled guidance was considered but ruled out since it was vulnerable to jamming by the enemy and the necessary radio beacons providing the navigation signals could be disabled or destroyed by enemy action. The inertial guidance system was chosen because it was autonomous and independent of any communications with the ground. Radio transmitters were however installed in some later versions to provide telemetry about the locations of the impacts of the bombs.

      Aware that the enemy could locate the launch sites by tracking the trajectory of the missile which was aimed directly at the target, a steerable version of the V-1 was also being developed to enable the bomb to change course and confuse the tracking radar, but the war ended before this was ready.

      Besides the air launched versions, several longer range models were produced.

      Also several manned versions were built, one piloted by famous, daring aviatrix, test pilot and Nazi poster girl Hanna Reitsch, was used for investigating the aerodynamic and control properties of the plane. Other manned versions were intended for attacking high value targets,but they were considered to be suicidal even for simple flight testing. Meanwhile, elements in the Luftwaffe were planning a suicide division and 70 volunteer pilots had signed up, but Albert Speer, head of the German war industry, persuaded Hitler that such missions were not in the tradition of the German warrior and so the idea of the piloted V-1 was abandoned.

  • Effectiveness of the V-1
  • The V-1 was an elegant, low cost engineering solution to a complex problem but because it was a single use projectile with a limited payload, its cost effectiveness in terms of cost per target destroyed could not compare with the cost and accuracy of conventional bombers which carried out multiple sorties with much greater bomb loads.

    Over 30,000 V-1s were produced between June 1944 and March 1945 with around 10,000 fired at targets in Britain. Of these only 2,419 reached London killing 6,184 people and injuring 17,981. The Belgium port of Antwerp was also a major target and was hit by 2,448 V-1s between October 1944 and March 1945. A total of around 9,000 were fired at targets in Continental Europe.

    The cost of the V-1 missile was only one sixth of the cost of the V-2 rocket and it carried a similar payload but it was inaccurate, slow and vulnerable to interception by fighter planes of the day and to anti-aircraft fire. However because it was so small it was a difficult target to hit.

    Its launch sites were also difficult to camouflage and were pounded by Allied bombers. The high g forces of up to 22 g experienced during launch and the severe vibration from the pulse jet during flight were a major sources of unreliability.

    The death rate inflicted on London was only 2.6 deaths per bomb but, because of the menacing noise of its engine which announced its approach, and its indiscriminate effects, it had the terrifying impact on the population. The V-1 was thus largely a terror weapon and had little overall impact on the outcome of the war.

In 1942 the German V-2 Missile, the world's first long range ballistic missile and the progenitor of all modern rockets, was successfully fired, without a warhead, for the first time on the 3rd October 1942. Two months later Adolf Hitler signed the order approving it for production. It was a single stage rocket fuelled by alcohol and liquid oxygen (LOX) producing 25,000 kg (55,100 lb) of thrust at lift off. Burning 58 kg of alcohol and 72 kg of oxygen per second for 65 seconds the rocket motor would propel the missile to an altitude of 93 km (58 miles) at speeds up to Mach 5 and drop one ton of high explosive on a target up to 320 kilometres (200 miles) away just five minutes after launch.

It was also the first known human artifact to enter outer space reaching an altitude of 189 kms (117 Miles) in tests designed to measure cosmic rays, meteoroid flux and to explore conditions in space.

Known originally as the Aggregat 4 - "Assembly" 4 or the A-4, it was dubbed by the Propaganda Minister Josef Goebbels as the Vergeltungswaffe 2 - "Vengeance Weapon 2".

Its first operational flight was aimed at Paris on September 7, 1944 three months after the first V-1 entered service, but it did not reach its target. The next day, V-2s were launched against both Paris and London, The first missile landed at Charentonneau south-east of Paris killing six and the second landed at Chiswick in West London killing three people.

The V-2 rocket had its roots in Germany's enthusiastic rocket societies such as the Verein für Raumschiffahrt (VfR) - "Society for Space Travel" and inspired by Hermann Oberth's landmark book Die Rakete zu den Planetenräumen - "The Rocket into Interplanetary Space" published in 1925. Developments in the 1920s attracted the attention of the German military establishment, still smarting under the severe restrictions imposed by the Treaty of Versailles after World War I on the weapons Germany was allowed to use. Rocket technology was not included in these restrictions and rockets were seen as potentially superior weapons to artillery, having a longer range and greater mobility.

Oberth's publication received a much more sympathetic response in Germany, than Goddard's similar publication did six years earlier in his native USA.

  • Building the Team
  • The development of Germany's military rocket technology was led by German Army Artillery Officer Walter Dornberger. In 1932 he began to recruit prominent members of the VfR to develop a series of experimental rockets for the army at his weapons development site at Kummersdorf near Berlin.

    The first three recruits included a recently graduated 19 years old, Prussian aristocratic rocket enthusiast and theoretician Wernher Magnus Maximilian, Freiherr von Braun to whom Dornberger gave a grant to study "Construction, Theoretical, and Experimental Solution to the Problem of the Liquid Propellant Rocket"; for which von Braun subsequently received a PhD for his thesis in 1934.

    Joining him were Heinrich Grünow, an exceptional mechanic who could translate ideas into hardware and Walter Riedel, an engineer with the Heylandt Company which produced liquid oxygen, he was an early experimenter with rocket motors which he had used in a rocket propelled car. Also known as "Papa" Riedel he became head of the technical design office and deputy to von Braun even though he lacked formal qualifications.

    As Dornberger's team expanded, in 1934 Arthur Rudolph, another of Heylandt's engineers who had designed a prototype liquid fuelled rocket motor for the army also joined the team as head of the Development and Fabrication Laboratory where he specialised in production and in the same year, gyroscope expert Johannes Maria Boykow technical director of Kreiselgeräte - "Gyro Devices" company was invited by von Braun to join the rocket team to take responsibility for guidance and stability.

    In 1936 chemical engineer, working in the army's Ordnance Research Test Section, Walter Thiel was transferred to Dornberger's team to develop a new high power engine.

    He was followed in 1937 by an old friend of von Braun, Klaus Riedel (no relation to Walter) who had been working at Siemens after playing a major role in rocket development at "Raketenflugplatz Berlin" - the launch site of the VfR. Riedel took up the position of Head of the Test Laboratory.

    The same year Rudolf Hermann who had built a supersonic wind tunnel at the Technical University of Aachen was recruited as chief aerodynamicist to develop a similar facility for Dornberger's team.

    In 1938 the army's weapons research establishment was relocated to Peenemünde on the Baltic coast and the German Ordnance Department requested that the Peenemünde team develop a ballistic weapon with a range of 200 to 300 kilometres and a payload of one ton.This was the birth of the V-2.

    In 1939 Hermann Steuding a mathematician from Darmstadt Institute of Technology (DIT) joined the group to set up an Aeroballistics and Mathematics Laboratory and he in turn recommended his friend, Flight Captain Ernst Steinhoff a specialist in aeronautical engineering at DIT who joined the group to take charge of the Guidance, Control and Telemetry Laboratory which had been without a leader since Boykow's untimely death in 1935.

    In 1940 electronics engineer Helmut Gröttrup joined Steinhoff's team in charge of electrical and flight control systems.

    Each of these men brought with them experienced fellow engineers and together they formed the initial core of the team which eventually developed the V-2.

  • The Design and the Technology (See photo and cutaway diagrams of the V-2 Rocket).
  • The V-2 was an exceedingly complex machine pushing the boundaries of existing technology on several fronts and was subject to constant changes as the development progressed. The exigencies of war and the consequent political pressures forced the adoption of unrealistic production targets so that it was introduced when it was far from ready and some 65,000 engineering changes were made to the missile design between the decision to put it into production in October 1942 and the end of the war. Procurement of complex, precision parts made from exotic materials during times of severe scarcities only added to the problems. Considering that only 6,152 V-2s were built and only 3,170 were used in anger, very few of them were the same, a situation which was of great concern to the engineers involved.

    The main components are described below.

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    • The V2 Engine
    • The rocket motor design was the result of many years experimenting with different fuels, combustion chamber and nozzle shapes and sizes, fuel pumping systems, injector designs and cooling systems carried out by Walter Thiel and his team. The motor was designed to generate about 55,000 lbs (24,947 kg) of thrust on start up increasing to 160,000 lbs (72,574 kg) when the maximum speed was reached. The motor typically burned for only 60 to 65 seconds, pushing the rocket to a speed of around Mach 5.

      The fuel chosen was a mixture of 75% ethyl alcohol (ethanol), derived from fermenting potatoes, with 25% water. Thirty tons of potatoes were required to manufacture the fuel for each V-2. The oxidiser was liquid oxygen (LOX). The water was added to the alcohol in order to reduce the temperature of the combustion gases and had a limited effect on the engine performance.

      The engine consisted of three parts, a spherically shaped combustion chamber which opened out into the main rocket thrust nozzle, the injectors for atomising the fuel mixture and feeding it into the combustion chamber and the pump for delivering the fuel and oxidiser to the injectors.

      The Combustion Chamber - Thiel was able to reduce the length and weight of the combustion chamber and nozzle be ensuring better atomisation of the propellants which resulted in faster burning so that it was no longer necessary to have a long burning path to ensure complete combustion of the fuel.The burning fuel however reached temperatures of 2500 - 2700 °C (4500 - 4900 °F) which was hot enough to melt steel.

      Thermal Management - To contain the extreme temperature combustion products, regenerative cooling was use to cool the walls of the combustion chamber and exhaust nozzle. This was accomplished by using double skinned walls for the combustion chamber and nozzle with a cavity between the inner and outer walls to act as a cooling jacket. The fuel mixture of alcohol and water was fed through a manifold near the base of the nozzle to circulate through the cavity on its way to the injectors at the top of the combustion chamber, simultaneously cooling the chamber walls while pre-heating the fuel to improve combustion efficiency. This method alone however was insufficient to avoid hot spots on some sections of the chamber walls.

      To overcome this remaining problem Moritz Pöhlmann, one of Thiel's engineers, suggested injecting some of the fuel directly into the chamber through perforations in the chamber walls where the fuel evaporated creating a local cooling effect and forming a cooled boundary layer which further protected the wall of the chamber. The technique is now known as film or veil cooling. 10% of fuel flow was used for film cooling and this reduced the heat transfer to the chamber walls by approximately 70%

      Fuel Mixing and Combustion - The purpose of the injectors was to create controlled combustion of the propellants, avoiding any tendency to explode while at the same time optimising the efficiency and speed of the burning process. To achieve this both the fuel and oxidiser have to be evenly distributed throughout the combustion chamber and they need to be atomised into very small droplets to facilitate mixing as well as to increase the burn rate of the fuel.

      In the V-2 engine, the fuel and oxidiser were pre-mixed in eighteen large bell shaped injector "pots" arranged in two concentric rings on the dome of the combustion chamber. The open end of each bell was mated to a similar sized aperture in the combustion chamber through which the atomised mixture of fuel and oxidiser passed.

      Like the combustion chamber, the body of each injector pot was also double walled and the fuel passed into this injector cavity at high pressure from the cavity around the combustion chamber. A series of small nozzles around the circumference of the inner wall of each injector body directed fine swirling jets of fuel droplets towards the centre of injector chamber. At the centre of the closed end of the bell, the oxidiser was fed at high pressure into the centre of injector chamber through a single perforated cup-shaped injector, similar to a shower head, which separated the oxidiser in to tiny droplets and directed them against the jets of fuel coming in the other direction from the wall of the injector pot. Burning did not take place until the mixture entered the combustion chamber.

      The oxygen was supplied from a turbopump to the injectors through eighteen large pipes.

      The Rocket Thrust Nozzle - The bell-shaped exhaust nozzle is designed to extract the maximum thermal energy from the exhaust stream, converting it into kinetic energy by reducing its temperature and pressure, thus increasing the exhaust velocity and improving the overall efficiency of the rocket.

      The exhaust gases emerge from the aperture in the combustion chamber at high pressure and temperature travelling faster than the speed of sound. As they enter the wider, expansion part of the nozzle, we should expect the exhaust temperature and pressure to be reduced by the Joule Thomson Effect which dictates that increasing the volume of a compressible fluid, reduces its temperature and pressure. (As in a refrigerator). On the other hand, expanding the flow of a non-compressible fluid, such as water, after passing through a constriction would reduce its speed. However the exhaust gas is not a non-compressible fluid. When the flow rate of the rocket exhaust is faster than the speed of sound, the effect of the lower pressure, due to the expansion of the gas, can not propagate back through the nozzle aperture and the Conservation of Energy Law dictates that the reduction of the pressure and temperature energy is compensated by the increase in the kinetic energy of the gas flow and hence its speed.

      A Steam Engine in Space - Previously, all liquid fuelled rockets had used pressurised fuel tanks to feed the propellants into the engine, but this method could not produce the flow rate of 58kg (128 lbs) per second of alcohol and 72 kg (160 lbs) per second of LOX necessary to generate the 25,000 kg (55,100 lb) of thrust needed for the V-2.

      Von Braun came up with the idea of using turbopumps to perform this function after seeing similar pumps used by the fire service to provide high pressure water jets. The alcohol and the LOX were delivered to the combustion chamber by two rotary pumps, driven by a central 580 horsepower steam turbine all mounted on the same shaft running at 3,800 rpm.

      The steam to power the turbine was raised by a hypergolic (self igniting) mixture of hydrogen peroxide (80 %) and water (20%) reacting with a solution of sodium permanganate (66%) with water (33%) which produces large quantities of steam as in the steam piston catapult developed by Hellmuth Walter for the V-1 launching system.

      Pumping these hypergolic liquids into the mixing chamber still employed the older method of pressurised fuel tanks with compressed air or nitrogen used to provide the necessary 32 atmospheres of pressure.

      The pumping assembly had to cope with extreme temperature difference between the +425 °C of the superheated steam in the turbine and the -183 °C of the LOX in one of the pumps. Furthermore, special seals, gaskets and bearings had to be developed since the pure oxygen causes the breakdown of organic seals and lubricants. Though the turbopumps replaced the pressurised fuel delivery system, the fuel and oxidiser tanks still had to be pressurised with nitrogen to prevent cavitation in the powerful turbopumps.

      Thiel's death in the RAF bombing raid on Peenemünde in August 1943 was a big loss to the team.

      While technically his motor was very efficient, the complex, 18 injector 'basket-head' design and the plethora of hand-formed pipes needed to feed it were not suitable for volume manufacturing and it was a plumber's nightmare to assemble. Furthermore the long rigid fuel and LOX pipes made it impractical to mount the motor on a gimbals which was the preferred method for directional control of the rocket.

      In 1942, Thiel had already begun working on the development of a Mischduese ("mixing nozzle") injector plate, a much simpler system for injecting the propellants into the chamber consisting of a simple flat injector plate, containing rows of fine holes, mounted at at the head of the chamber. This eliminated the multitude of fuel and oxidizer feeder lines producing a cleaner design with better mixing properties and improved reliability and it also allowed for gimballed suspension of the rocket motor. This new design unfortunately had combustion instability problems which could not be overcome before the end of the war and as a result the original basket head design had to be put into production instead.

      Thiel's injector plate concept is the basis of today's advanced rocket motors such as those used in the Saturn V.

      After the death of Thiel, Martin Schilling took over responsibility for the engine development.

    • Ballistics and Aerodynamics
    • The trajectory of a ballistic missile is only controllable during the launch period during which it accelerates to a target velocity pointing in the right direction at which time the fuel supply is shut off. Once the motor is switched off, the missile coasts towards its target following (almost) the typical ballistic trajectory of an artillery shell determined by its velocity and direction of flight at the moment of switch off. After this point there is no possibility to alter course to correct for any initial guidance or alignment errors, drift, side winds, headwinds, tailwinds, or any buffeting by the atmosphere as the missile arcs upwards to its apogee then descends to Earth.

      In the case of the V-2, the flight time to the target is around 5 minutes but the rocket is only powered for the first 60 seconds of the flight and the guidance control is therefore only effective during this period during which it covers 27 kilometres (17 miles). For the remaining 290 kilometres (180 miles) to the target, the missile is in free flight subject to atmospheric conditions. This placed limitations on its targetting accuracy.

      (See Launch Sequence below)

      Simple ballistic calculations for projectiles such as artillery shells assume that the gravitational force is constant and that the projectile is not subject to aerodynamic drag or wind conditions so that it follows a parabolic path in a vertical plane. These assumptions are not valid for a missile which travels very fast over long distances and reaches very high altitudes above the Earth's atmosphere and the following effects, all of which affect targetting accuracy, have to be taken into account for setting the missile's velocity and direction at the start of its ballistic flight.

      • The rocket travels very fast through the atmosphere where it is subject to very high drag shortening its range.
      • The density if the air decreases with altitude so that the drag also decreases with altitude and above the atmosphere there is no drag. The parabolic path of the V-2 takes it above the level of the stratopause (50 -55 kms) where the air density is only 1/1000 of that at sea level. Flying above the atmosphere enables maximum range to be achieved.
      • Aerodynamic control surfaces such as wings, fins and rudders do not work where there is no air.
      • At very low speeds, immediately after lift off, the effectiveness of aerodynamic control surfaces is also very low or impractical.
      • Heavy rockets can not take off at the desired angle of elevation necessary for optimising the range because the initial speed does not built up quickly enough and aerodynamic forces on the control surfaces are too weak to stabilise the vehicle and keep it airborne against gravity and wind so that the rocket would topple over. They must therefore take off vertically and be subsequently tilted to the optimum launch angle as the speed increases to the desired launch speed before entering their ballistic flight path.
      • Note that although the propulsive force of the rocket motor is reasonably constant while it is in operation, the acceleration of the rocket actually increases during the flight. This is because the mass of the rocket decreases as the fuel is used up so that the same force delivers greater acceleration. (Newton's Law:  F = M.a). This also explains why rockets may be very slow to rise from the launching pad, since that is when the rocket's weight is at its maximum.

      • Control of the rocket's attitude or direction above the atmosphere or at very low speeds needs control of the direction of the rocket exhaust or the use of ancillary thrusters.
      • The gravitational force pulling the rocket downwards is not constant during the flight but decreases with altitude, thus increasing the missile's range. The apogee of the V-2 trajectory at its maximum range is 94 kilometres (58 miles), just below the Kármán Line (100 kms), and the gravitational force at the apogee is 2.9% less than the force at ground level.
      • The ballistic flight of the rocket starts at very high altitude, much higher than the level of the target, so that the direction and speed of the rocket when the engine is switched off must take this height difference into account.
      • The weight of the rocket reduces and its centre of gravity changes as its fuel is used up causing its attitude and hence direction to change.
      • No directional, or range controls to compensate for external conditions are possible once the rocket has entered its ballistic trajectory.

      All of the above factors have an effect on the actual trajectory of the missile and need to be incorporated into the target setting of the missile. These factors are considered in more detail on the page about Missile Ballistics and Aerodynamics.

      See also Tsiolkovsky Rocket Propulsion Theory

      The basic V-2 aerodynamic configuration was based on the shape of the Wehrmacht "S" model bullet. Just like an arrow, fins provided longitudinal stability keeping the rocket "nose-on" into the airflow. But the attitude of the V-2 had also to be controlled when rising vertically at near zero speed, where aerodynamic surfaces are ineffective and it had to remain stable and controllable up to supersonic speeds of Mach 5 at the limits of the Earth's atmosphere. At the time there was no practical experience or available data on operations at these speeds and altitudes on which to base the designs so that extensive test programmes were required to improve the design which went through numerous iterations. Tests were carried out by Rudolf Hermann who built a supersonic wind tunnel at Peenemünde for this purpose but they sill needed to be supplemented by a comprehensive programme of flight testing to verify the results.

    • The Guidance System
    • The development of the guidance system was a slow and painful process involving in succession three different subcontractors responsible for the main development as well as academic institutions and several other companies involved in sub-systems work. All of these subcontractors however were heavily involved in other major military projects as part of the war effort and they had limited resources available for the V-2 project which was given a lower priority. There were no engineering precedents for such a system and many alternatives were explored by trial and error as part of the development. Management was complicated with engineers from multiple companies working simultaneously on alternative systems and sub-systems. Eventually, von Braun, dissatisfied with the progress, took the work in house at Peenemünde and appointed his own manager of the guidance project.

      The V-2 was launched from locations whose coordinates were known, so the azimuth and distance to the target could be determined. The direction of the missile was set towards the target by aligning fin 1 of the rocket along the desired bearing. This automatically aligned the bearing of the yaw gyro with the target direction.

      The guidance system had three design objectives:

      • Cut off the thrust of the motor at a predetermined velocity depending on the required range. Known as Brennschluss
      • Tilt the rocket so that its axis was 47° to 49° degrees to vertical at the start of its ballistic trajectory depending on the desired range.
      • Stabilise the roll and yaw to prevent the rocket wandering off the correct bearing.

      It must also function with acceleration forces of up to 8g and speeds of up to Mach 5 from sea level to the rocket's burn out height of 30 kms (20 miles).

      The initial proposal for guidance was to use radio "guide beams" transmitted from the ground, to keep the missile on course, but this was rejected, mainly because of the vulnerability to jamming by the enemy who could also home in on and knock out the radio beacons, but also because the main industry specialist manufacturers had more pressing military priorities. Instead a system to control the missile's pitch and yaw based on a gyro stabilised reference platform was adopted because it was independent of signals from the ground. Towards the end of the war however the decision was reviewed and an alternative system using radio guide beams was also developed.

      In 1934 von Braun engaged Johannes Maria Boykow technical director of Kreiselgeräte - Gyro Devices, to design a guidance system based on a stable gyroscopic inertial platform for the A3 experimental rocket which was to be the forerunner of the V-2. Boykow's initial design was only suitable for maintaining the rocket in a vertical trajectory.

      For sensing, it used two gimbal mounted, position gyros to monitor pitch and yaw but had no roll control. Two linear accelerometers in the form of little wagons moving on tracks sensed any tipping movement of the rocket to the right, or left (yaw) and backwards or forwards (pitch) and provided signals representing the acceleration in these two planes.

      Electronic analogue computers integrated these signals over time to give the corresponding speed of the deviation from vertical and the lateral deviation or displacement due to wind forces from the desired course was obtained by double integration over time.

      The system also incorporated three rate gyros mounted on the rocket body to monitor the rate of turn in any direction, pitch yaw and roll, and to provide stable signals to avoid overshoot and oscillation of the controls. (See more about Gyroscopes and Guidance)

      The guidance control system combined the signals from the inertial platform, representing deviations from the desired position, and mixed them with the rate signals for stability and fed the resulting signal to servomotors driving actuators which operated molybdenum jet vanes or rudders in the rocket's exhaust flow to execute course corrections.

      Boykow was an ideas man who left to his subordinates the task of converting these ideas into practical systems. He had planned to use an integrating accelerometer to calculate the velocity of the rocket but he died in 1935 before many of his ideas could be fully developed. However many of his original ideas were used in later systems development.

      Unfortunately his design for the A-3 and its immediate variants proved difficult to scale up and was not suitable for controlling the higher forces and speeds experienced by the V-2 (A-4). The roll controls were also inadequate allowing excessive roll to build up which led to instability and loss of the rocket. The servo control mechanisms were also not powerful enough to operate the jet vanes and the scheme for tilting the rocket into the angle needed for its ballistic flight was too abrupt and unworkable.

      In 1938 von Braun sought the help of Siemens whose engineer Karl Fieber was appointed to improve the shortcomings in Boykow's design. He developed a simpler system, known as the LEV-3, using only two electrically driven displacement gyroscopes rotating at 30,000 rpm, mounted on gimbals, the "Horizont" (mounted horizontally) with a single degree of freedom which controlled pitch, and the "Verticant" with 2 degrees of freedom (mounted vertically) which sensed both roll an yaw to provide a three axis stable platform. The gyroscopes would maintain their original orientation, no matter how the rocket moved. Displacement pick-offs on the gyro axes provided a measure of the rocket's deviation from its desired course and these signals were amplified in thyratron amplifiers and used to activate direction control mechanisms. Roll compensation was provided by electric motors which adjusted small aerodynamic trim tabs (air vanes) at the tips of the four fins.

      The main yaw and pitch control however required much higher forces to change the direction of the rocket, and these also had to operate at both low rocket speeds immediately after lift off where aerodynamic controls are inefficient as well as at very high altitudes above the Earth's atmosphere where aerodynamic controls are not possible.

      The solution was to use four jet vanes or rudders to deflect the rocket exhaust and thus change its course. Similar vanes made from molybdenum alloy had been used in the A3 but the electric servos controlling them were not able to provide sufficient force. In the V-2, the jet vanes were activated by hydraulic power provided by pumps driven by electric motors in response to amplified control signals from the pitch and yaw gyros. The cost of the jet vanes was also reduced by making them from graphite rather than the molybdenum used in the A-3.

      Fieber's system also used the Horizont (pitch) gyro to tilt the rocket to its required angular attitude after its vertical launch. Four seconds after lift off a clockwork mechanism gradually tilted the pitch gyro by 47° to 49°, depending on the desired range, and the pitch control mechanism automatically aligned the rocket with the new gyro reference angle to set it into its maximum trajectory.

      The above two control systems oriented the rocket along a pre-determined path in a vertical plane pointed at the target but they did not control its velocity and hence its range. This was controlled by the timing of the engine cut-off. As with the directional controls, the range is set at the point of cut-off and no further adjustments are possible.

      Three different methods of determining the cut off point were tried. The simplest, but very crude, method was to fuel the rocket with exactly the correct amount of fuel so that it cut off when the fuel was exhausted. This however did not provide the precision required and two other systems, one using accelerometers and the other using radio signals from the ground were developed.

      The LEV-3 system was modified by the addition of a Pendulous Integrating Gyroscopic Accelerometer or PIGA, developed by Fritz Mueller at the Kreiselgeräte Company in 1939 (See details of How the PIGA Works). The torque sensor in the PIGA's main shaft provided an electrical signal representing the rocket's acceleration while cumulative revolutions of the shaft represented the simultaneous integration of this acceleration over time providing a signal corresponding to the rocket's velocity. Cam switches on this shaft, or on an auxiliary shaft geared to it, were used to initiate missile control sequences such as engine throttle down and shut off when the rocket had reached pre-determined velocities. The PIGA was highly accurate achieving error rates of between 1 part in 1000 to 1 part in 10000.

      The distance travelled could be also be determined by integrating the speed over time in an electronic analogue computer circuit.

      The alternative to the PIGA accelerometer system for determining the velocity of the rocket was a Doppler system devised by Professor Wilhelm Wolman of Dresden University in 1940. It worked by sending a radio signal from a base station on the ground to a transponder in the rocket. The relative velocity between the fixed base station transmitter and the receiver in the moving rocket caused an apparent frequency shift in the received signal, proportional to the relative velocity. The received signal was then retransmitted by the rocket's transponder back to a receiver at the base station undergoing a second frequency shift on the way. By measuring this two way frequency shift, the velocity of the rocket could be determined. When the rocket reached its target velocity, a separate signal was sent to the rocket to shut off the rocket's motor.

      The Doppler cut off system was used in the first successful launch of the V-2 in 1942. Surprisingly this electronic system was not as accurate as the PIGA mechanical gyro system.

      Concerned by the slow progress of the development of the guidance system, in 1939 von Braun sought the help of the Askania company where Waldemar Möller had developed a three axis inertial system for the Luftwaffe. Unfortunately Ascania's main guidance technology had been optimised for submarine use and was not transferable to airborne missiles. Möller however showed the need for rate gyros to provide damping to improve system stability.

      Input was also requested from the Anschutz Company who manufactured autopilots and gyrocompasses.

      Later in 1939, frustrated by the continued lack of progress, von Braun eventually brought all guidance development in house and appointed Ernst Steinhoff from the University of Darmstadt as head of the Peenemünde Guidance Division with responsibility for Flight Mechanics, Ballistics, Guidance and Control and Instrumentation. Steinhoff, an enthusiastic Nazi party member, took over management control of the relevant projects of the Siemens, Askania and Anschütz companies.

      The same year Steinhoff recruited Helmut Hoelzer from Telefunken in Berlin. Like Steinhoff, Hoelzer was another Darmstadt alumnus but his studies had been interrupted when he was thrown out after getting into an argument with a Nazi student organisation. His task was to develop an alternative guidance system based on radio guide beams, a technology which had been initially rejected. It was considered that the guidance system was only active for the first 60 seconds of the flight, too short a time for the enemy to instigate electronic countermeasures. Furthermore, like all radio systems used on the V-2, the system could switch between 10 different frequencies to make jamming even more difficult. (Note that the Austrian born Hollywood film star Hedy Lamarr patented a similar frequency hopping system for controlling torpedoes in 1942.)

      Hoelzer's system, was based on an instrument landing system developed by the Lorenz company, similar in many ways to the modern aircraft instrument landing systems. It used a 3 kiloWatt, 50 megaHertz radio frequency transmitter feeding alternately with a switching frequency of 50 Hertz, two dipole antennas located 200 metres apart, 12 kilometres behind the missile launch point, sending two parallel, overlapping radio beams in the direction of the target. The line of overlap thus corresponded to the guideplane or direct trajectory towards the target. A radio receiver on the missile travelling on track would see equal signal strength from each transmitter and hence a constant amplitude signal. But if the missile diverged from the guide plane, one of the signals would be larger than the other and the receiver would see an error signal in the form of square wave whose amplitude was proportional to the lateral divergence from the desired track. The guidance control system used this error signal to activate the rudders to bring the error back to zero. By modulating the alternate transmitted signals with different audio frequency tones, it was possible to determine whether the deviation was to the left or to the right. The electronic, radio beam guidance system was potentially more accurate than the mechanical, gyro based system.

      This system, like all feedback control systems, suffered from possible overshoot and consequent instability as the momentum of the missile would keep it moving past the guide plane after the error signal had been zeroed causing an error signal in the opposite direction. In 1940 Hoelzer developed an electronic mixing system with an analogue computer to modify the received error signal and damp out these oscillations and in 1942 he built an analogue computer to calculate and simulate V-2 rocket trajectories.

      Hoelzer's analogue computer mixing device was later developed for use in guidance systems based on gyroscopic controls where it enabled stability to be maintained using position gyros only, thus eliminating the need for rate gyros.

    • Construction and Subsystems
    • The head of the Design Office and Chief Designer of the V-2 was Walter Riedel, a founder member of the team. Standing 14 m (46.1 ft) high, the V-2 weighed 12,500 kg (28,000 lb) when fully fuelled and ready for flight, carrying a payload of 1000 kg (2,200 lbs). The fuselage was originally constructed from aluminium, but this had to be reinforced by steel bands after early models broke up in flight. Both the alcohol and oxygen tanks were constructed from an aluminium-magnesium alloy.

      The layout of the warhead, the guidance equipment, the fuel tanks and the engine within the fuselage is shown in the V-2 cutaway drawings.

      A 50 volt nickel-iron battery provided the main electrical power and two 16 volt nickel-cadmium batteries powered the gyroscopes. Electronic inverters converted the DC battery power for the gyros to 500 Hertz, three phase AC which drove the rotors at 30,000 r.p.m.

      Pneumatic power to operate valves and to pressurise the fuel tanks was provided by nitrogen gas bottles.

    • The Warhead
    • Like the V-1 the V-2 could carry a warhead of 1 ton but because frictional and shockwave surface heating of the V-2 fuselage during its high speed re-entry through the atmosphere raised its temperature to over 650° C (1200° F) it was not possible to use the high explosives employed in the V-1 because they were too sensitive to heat. Instead, 738 kg of less explosive Amatol Fp60/40 was used as part of its 975 kg payload. Nevertheless the package, combined with the impact of the 4 ton missile body hitting the target at three times the speed of sound was capable of flattening a city block.

    • Launch Sequence
    • -60 seconds - Main alcohol and oxygen valves opened allowing 9 kg of fuel per second by gravity into combustion chamber. Igniter lit under motor

      -20 seconds - Ignition confirmed and turbopump starts rotating

      -10 seconds - Turbopump now running at maximum rpm. External power supplies switched off and internal batteries switched on. Initial thrust stage starts

      -5 seconds  - Thrust reaches 8,000 kg, and all systems working

        0 seconds  - Main thrust stage of 25,000 kg starts

      + 8 seconds  - External power supply jettisoned; all systems now running on internal power. Thrust rises to 25,000 kg;

      + 10 seconds - Lift-off; Acceleration at lift-off 1g. Trajectory timing sequence starts. Vertical axis still at 90°.

      + 14 seconds - Rocket starts inclining from vertical

      + 24 seconds - Rocket reaches the speed of sound, Mach 1

      + 35 seconds - Mach 2 reached

      + 50 seconds - Completes pre-programmed tilt of approximately 47°

      + 54 seconds - Burnout; Acceleration at burnout 7g. Turbopump stopped at altitude of 30.5 km (20 miles) and distance down track of 27.3 kms (17 miles) when rocket is travelling at Mach 5.5. The rocket now continues on ballistic trajectory for another 4 minutes, silently impacting its target at a speed of Mach 3.

      The total burn time - 65 seconds of which 55 seconds are at full power.

    • The Launching System
    • Klaus Riedel designed the V-2 launching system. It was designed to operate from mobile launch sites to avoid detection by the enemy and needed over 30 support vehicles to carry the propellants, test stands, pumps, spares radio and service equipment. The rocket was brought to the site on a towed transportation frame called the Meillerwagen after the name of its manufacturer. The frame could be elevated by a hydraulic ram to hold the rocket in place during the set up, fuelling and launch. Riedel was also involved in designing the submarine version of the V-2, launched from a submersible canister. He was killed in a car crash in 1944 when he fell asleep at the wheel and ran into a tree.

    • The Production
    • Development and engineering models of the V-2 were produced on the Peenemünde site but following a major bombing raid by the Royal Air Force on 18th August 1943, just before full production was to start, it was decided that volume manufacture of the missiles would take place in a less vulnerable, underground facility near Nordhausen, in the Harz Mountains. Arthur Rudolf, Chief Production Engineer at Peenemünde, was put in charge of making the transfer. The site chosen was formed from a series of tunnels in what had previously been a gypsum mine but were now used for secure storage of fuel and chemicals. The factory was known as Mittelwerk - "Central Works" and became a place of unspeakable horror.

      Because of Germany's chronic manpower shortages as a result of the war, many factories used prisoners and concentration camp inmates as slave labour, though not for highly secret projects. But Peenemünde was so desperate for labour that by June 1943, at the request of Rudolf, they had already started using prisoners from the Buchenwald concentration camp supplied by the SS. The volume production facility at Mittelwerk however needed many more. Before production could start, the tunnels had to be extended and expanded to accommodate the huge rockets as well as the overcrowded primitive "sleeping quarters" for the workers themselves. (Calling their accommodation "living quarters" would imply that the unfortunate inmates actually had a life).

      The construction and manufacturing were carried out by prisoners from the Mittelbau-Dora concentration camp, a sub-camp of Buchenwald under the brutal supervision the psychopathic Hans Kammler of the SS. In just four months, caverns and interconnecting tunnels were excavated, manufacturing equipment was installed, workers were moved in and trained and on New Year's Eve the first prototype V-2 was delivered.

      Rudolf, a committed Nazi, was in charge of day to day production operations at Mittelwerk and by the end of the war almost 6000 rockets had been delivered, 150 - 200 from Peenemünde and 5789 from Mittelwerk, but the human cost was horrendous.

      Over a year and a half, 60,000 slave labourers from all over occupied Europe were put to work in the Mittelwerk's tunnels manufacturing weapons to be used against their families and compatriots back home, 20,000 of them died there from starvation, disease, beatings, shootings, accidents, exhaustion and collapse in the most squalid and inhuman conditions. Of these deaths, 350 of them were by hanging including 200 executed for alleged acts of sabotage.

      Because the production was started before the design was ready, the first deliveries were essentially hand made prototypes with, yet to be resolved or even discovered, structural and performance weaknesses. Von Braun's deputy, Walter 'Papa' Riedel, head of the design office was overwhelmed by the scale of the task, the shortages of materials and the volume of changes. As a result he was unfairly blamed for delivery delays and was replaced by Walther Riedel (no relation).

    • Accuracy
    • Because the V-2 was only guided for less than the first 10% of its trajectory it was significantly less accurate than the V-1 which was guided all the way to its target. The Circular Error Probability (CEP) for the V-2 was 17 kms (11 miles) compared with 13 kms (8 miles) for the V-1.

      Because of its poor accuracy, the V-2 was incapable of hitting precise military targets and from 320 kilometres (200 miles) away it could only hit a city-sized target causing random civilian casualties. In view of this known inaccuracy, the resulting civilian deaths could not be considered as what military chiefs euphemistically call "collateral damage". They were a deliberate objective.

      Since the V-2 was deployed before the development was complete, it is likely that later versions would have had improved accuracy.

  • Effectiveness of the V-2
    • The Military Value
    • There was no defence against the V-2 and, like the V-1, it had a considerable psychological effect on the civilian population. Once it was airborne it was impossible to detect and to intercept. Its ballistic trajectory enabled it to travel in silence giving no warning before impacting its target at speeds three times faster than the speed of sound. Its extreme speed also meant that it was too fast to stop with fighter planes. Its long range and mobile launching platforms also minimised the risk of casualties to the launch crews and it was not necessary to risk German pilots to make it work.

    • The Military Cost
    • The V-2 rocket was made from expensive materials and used exotic fuels at a time of serious economic scarcities. Even though it was manufactured by slave labour, it cost around the same as a high performance fighter plane it but was only good for a single sortie. It carried a warhead of less than one ton and was thus an extremely expensive way of delivering a relatively small amount of explosive to its target so that many missiles would have to be launched in order to do significant damage. This was further compounded by its inaccuracy since the probability of pin-pointing and destroying a specific target was very small requiring several attempts to make a direct hit.

      By comparison a single Lancaster Bomber had a longer range and could carry eight tons of explosives to multiple targets with greater accuracy and it could be used many times over.

      Perhaps the greatest economic cost was the opportunity cost. The V-2 programme diverted resources from other more cost effective projects. The cost of the V weapons programme relative to Germany's economy was more than the relative cost to the Allies of the Manhattan Project which produced the atomic bomb which really did change the course of the war..

    • The Death Toll
    • The V-2 has the distinction that more people were killed manufacturing it than were killed by its use. Estimates of the V-2's effectiveness as a military weapon in terms of the people killed vary by up to 50%. According to a 2011, BBC documentary, an estimated total of 9,000 civilians and military personnel ware killed by the V-2 bombardment, while 12,000 forced labourers and concentration camp prisoners were killed producing the weapons.

      Its actual performance in the field is more revealing.

      Between September 1944 and March 1945 Germany launched 3,170 V-2s at Allied cities in Europe. The list below shows the numbers targeted at each city.

      • Belgium: Antwerp 1610, Liege 27, Hasselt 13, Tournai 9, Diest 2
      • England: London 1358, Norwich 43, Ipswich 1
      • France: Lille 25, Paris 19, Tourcoing, 19, Arras 6, Cambrai 4
      • Holland: Mastricht 19
      • Germany: Remagen Bridge (The last gateway to Germany over the Rhine - Occupied by US forces) 11 (Not one hit the bridge)

      Taking Antwerp and London together, two large cities which were easy enough to hit, 1376 were killed in Antwerp, including 567 who were killed by a single V-2 impact on a crowded cinema, and 2754 were killed in London. Thus a total of 4130 were killed by 2968 rockets, a hit rate of 1.4 deaths per rocket. A very expensive killing machine.

      Inaccurate guidance systems are often given as the reason for the low hit rate, but there were other factors. Early V-2 production models had structural weaknesses which caused them to break up in flight before reaching the target. It is also claimed that mis-information put out by the British Intelligence Services who announced, incorrectly, that the rockets had over-shot their targets, caused the German artillery units who had no way of checking their accuracy, to re-target their missiles so that they fell short of London.

    • The Human Cost
    • Estimates of the number of people who died manufacturing the rockets vary between 12,000 and 25,000 depending mainly on whether the victims died at their location of work or died in other places as a result of their brutal treatment and inhuman living conditions. An estimate of 20,000 deaths generally accepted as being reasonably accurate.

      The total production of V-2 rockets before the end of the war was around 6152, but only 3170 of these were actually used in actual military operations. About 600 were used for testing, and training, some were unserviceable, others had been destroyed by launching misfires, about 250 were still at Mittelwerk awaiting delivery and the balance was stored at German military facilities on their war fronts ready for action. The human cost of producing these 6152 rockets (using the estimate of 20,000 deaths) was 3.27 deaths per rocket, or 6.31 deaths per rocket if only the rockets actually used are taken into account.

    • The Affect on the War
    • Despite the enormous scale of the effort and the technical breakthroughs in rocket technology, the V-2 did not change the course of the war. It was too inaccurate, too expensive, its payload was too small and it was not available in sufficient quantities to make a difference so that it proved to be an enormous waste of resources.

      Bombing Dresden and Tokyo with conventional bombers each caused more destruction in a single day than both the V-1 and V-2 programmes together did in a year.

  • V-2 Take-over by the SS
  • Walter Dornberger, an artilleryman and rocket enthusiast, was also a wholehearted supporter of the Third Reich which gave him sufficient influence to obtain budget approval for his extended rocket development programmes and to maintain Hitler's lukewarm support, despite the enormous costs, through their numerous setbacks and delays. Most of the delays were however not caused by incompetence or things going wrong, but were initially the result of over-selling the programme targets and later in the war due to unrealistic demands for volume deliveries before the rocket was ready for production. This was compounded by severe materials and skilled manpower shortages. Despite the urgent need to get the V-2 into production, the Peenemünde design team were expected to develop several variants of the V-2 including a submarine launched version, a winged version, the A-9 or Glider A-4 which could increase range by gliding towards its target and another winged version, the Wasserfall designed as an anti-aircraft missile as well as several alternative fuel systems. All of these needed the development of radical new technologies and resulted in diluting the effort of the V-2 team on their primary task.

    By the summer of 1943 it was clear that Germany's triumphal war offensives had been halted and tide was turning against them. They had failed to establish air superiority during the Battle of Britain in the summer of 1940, but the biggest shock was the surrender of Germany's 6th Army to the Russians at Stalingrad in February 1943 followed by the surrender of the Axis forces in North Africa to the Allies in May the same year. Now a sense of desperation began to replace the belief in the invincibility of the German military might. Salvation was sought by means of new wonder weapons such as the V-1 and particularly the V-2 whose priorities were raised from desirable to essential but production was never enough to satisfy the pressing demand and infighting between the various military commanders and ministers intensified as they attempted to gain control these prestigious new weapons, to speed up production and to enhance their political power.

    The V-2 was an Army Ordnance project but its resources were allocated by the Albert Speer the Armaments and War Production Minister who was under pressure to supply more assets such as radar and war planes to the Luftwaffe. Speer made his first moves to gain influence in December 1942 by setting up the A-4 Special Committee to oversee production of the missile and appointing Gerhard Degenkolb a fanatical Nazi, who had sorted out problems with Germany's railways and transport infrastructure, to manage it. Dornberger however remained in charge of the overall project with his long term team member Arthur Rudolf, also a committed Nazi, as head of production. Degenkolb consolidated his power by creating a Labour Supply sub-committee to provide the manpower. By the following April, Degenkolb and Rudolf proposed the use of concentration camp prisoners for producing the V-2 and by June the first batch of the slave labour workers started work on production at Peenemünde.

    After the RAF bombing of Peenemünde in August 1943, it was decided to move the production to the less vulnerable underground tunnels at Mittelwerk with Arthur Rudolf as head of production and the Peenemünde facility was downgraded to a pilot plant manufacturing units for development and test.

    Waiting in the wings was Heinrich Himmler chief of the dreaded SS, Hitler's most loyal and fanatical staff the Schutzstaffel - "Protection Squadron" who were effectively a fourth, autonomous branch of the Wehrmacht the armed forces, who were responsible for the Gestapo (the secret police) and who set up and controlled the concentration camps.

    In September 1943 Himmler appointed SS Brigadier General Hans Kammler, who had been in charge of building of the extermination camps and gas chambers at Auschwitz-Birkenau, Majdenek and Belzec, to take charge of building the production facility for the V-2, giving Himmler's SS a foothold in the V-2 missile programme. Kammler used his control of the sources of concentration camp labour to gain overall control of the production at Mittelwerk. By this time Degenkolb had fallen from grace and ended up in a mental asylum.

    In February 1944 the V-2 was still not ready for deployment and the Army were desperate to get their hands on this new weapon, Himmler saw it as an opportunity to sideline Speer. Von Braun was summoned to Himmler's headquarters where the SS chief offered him all the resources at his disposal. Though not a Nazi ideologue, in 1940 von Braun had been pressurised into joining the SS and sought advice from his superior Dornberger who advised him that he had no option but to accept if he wanted to maintain his role in rocket science. He was not an active member of the SS and rarely if ever wore the uniform. This time he was more sure of his position but the pressure was different. Sensing a takeover of the the V-2 project by the SS, von Braun declined Himmler's offer, a rebuff which had its consequences.

    Later the next month von Braun, Klaus Riedel and Gröttrup were arrested, together with von Braun's younger brother Magnus, by the Gestapo and accused of sabotaging the V-2 programme by not being sufficiently committed to the war effort and of using the financing of the Reich to pursue th