Electropaedia Electrical Technology History, Energy Applications and Developments

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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.

2500 B.C. Sometimes known as the "Second oldest profession", soldering has been known since the Bronze Age (3500 to 1100 B.C.). A form of soldering to join sheets of gold was known to be used by the Chaldeans in Ur and also Mesopotamians (both in modern day Iraq). 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 stenciling 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.

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 - one of the Seven Wise Men of Greece - 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 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.

Thales left no writings - knowledge of him is derived from an account in Aristotle's Metaphysics.

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 Democtritus' 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 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 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 accurate measuring instruments in his time 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.

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 Newton and Lavoisier who showed that natural phenomena could be described by mathematical laws.

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. In 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.

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.

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.

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.

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.

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, 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 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.

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 earler, 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.

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.

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.

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.

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.

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 developed the compass, gunpowder, paper, paper money, canals and locks, block printing, moveable type, porcelain, pasta and many other inventions centuries before they were "invented" by the Europeans. 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 the industrial revolution 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 current 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. 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.

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.

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. 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. 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, but only about 300 or 400 were printed and it became known (recently) as "the book that nobody read".

1515 Leonardo da Vinci proposed the use of a large concave mirror to capture solar energy to heat water in a boiler used in a dye works.

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 view, dangerous at the time, that the world was not the centre of the universe. He was a contemporary of the more famous 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.

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.

1601 Danish astronomer and alchemist Tycho Brahe died in mysterious circumstances.

Brahe a wealthy, extroverted, nobleman with a lust for life and food, said to own one percent of the entire wealth of Denmark, had 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 set new standards for precise and objective measurements but he still relied on empirical observations rather than mathematics for his predictions.

Brahe died in great pain 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 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.

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 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.

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 obsevations. 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:

Kepler's laws were the first to enable accurate predictions of future planetary orbits.

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)

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.

Napier himself considered his greatest work to be a denunciation of the Roman Catholic Church which he pubkished 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.

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.

Pascal also did pioneering work on hydraulics, inventing the hydraulic press and explaining 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.

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 pressure by balancing the pressure force, due to the weight of the atmosphere, against the weight of a column of mercury.

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.

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

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.

1658 Irish Archbishop James Ussher, following a litereal 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 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 aiir 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 refered to Towneley's conclusions as "Towneley's Hypothesis".

1661 Dutch physicist and astronomer Christiaan 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.

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

The relationship was also discovered by English mathematician Richard Towneley as well as the French physicist Edme Mariotte in 1676 and is known by his name in non-English speaking countries.

1663 Otto van 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. The first machine to produce an electric spark and remained the standard way of producing electricity for over a century. Van Guericke was famed for his studies of the properties of a vacuum and for his design of the Magdeburg Hemispheres experiment.

1665 Boyle 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.

1675 Boyle 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, 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.

1679 German mathematician, diplomat and philosopher Gottfried Wilhelm Leibniz introduced 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..

Between the years 1673 and 1686 Leibniz developed the 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 and arguments about priority raged for many years after both men published their works. Leibniz's notation has been adopted in preference to Newton's but the concepts are the same.

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

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. 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 he conceived the idea of using the pressure of steam to drive a piston in a cylinder to perform a pumping action, the genesis of the steam engine. In 1707 Papin used his safety valve as a regulating device on a steam engine which he had built. Thereafter, it became a standard feature on steam engines saving many lives from explosions.

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.

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

Newton's first law of motion that "every body remains in a state of rest or uniform motion in a straight line unless compelled to change by some external force" is however a restatement of Galileo's concept of inertia or resistance to change which is measured by its mass.

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.

1705 English physicist and instrument maker Francis Hauksbee the Elder demonstrated an electroluminescent glow discharge lamp which gave off enough light to read by. It was based on van 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.

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. He 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 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 anthropometric 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:

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.

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.

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.

Until the advent of the battery, Leyden jars and 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.

1747 - 1753 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 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:

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

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 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. From a safe distance (in Dalibard's case eighteen miles away) they used a long pointed iron rod, insulated from the ground by 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 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.

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 kite experiments in 1752, one month after Dalibard, and invented the lightning rod. He 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 which we still use today.

Whilst it may be heresy to suggest that Franklin did not 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.

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 1889 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".

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.

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 large scale generation of electricity could never have happened without James Watt's steam engine which for many years, apart from a few hydroelectric schemes, was the prime mover for driving electric generators. Starting in 1769 Watt made a series of improvements to the steam engine originally patented in 1698 by the English engineer Thomas Savery in and improved by Thomas Newcomen in 1712. Watt's major contribution was the addition of a separate condenser, for condensing the steam, that could be kept cool while the working cylinder remained hot, thus reducing heat losses on every cycle and improving the efficiency of the machine.

Watt initially had difficulty in commercialising his engine but this problem was solved when he entered into partnership in 1769 with Matthew Boulton, a Birmingham entrepreneur who made ornamental metalware such as buttons, buckles and watch chains at his Soho plant near Birmingham. The Boulton and Watt company they founded was able to fund the further development and production of Watt's engines at Boulton's Soho plant.

The introduction of Watt's steam engine was a key event in the Industrial Revolution.

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.

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, in which he translated the geometrical study of mechanics used by Newton to one based on calculus.

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. 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 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.

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. Could it be animal electricity?. He found copper and zinc to be very effective in making the muscles twitch. His friend Volta on the other hand believed the electricity came from the metals and 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 1798 without knowing the outcome of the debate.

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

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

Charles' Law and Gay Lussac's Law together with Boyle's Law are known collectively as the Gas Laws.

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

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".

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 alieviate 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 metallugical 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.

1795 The hydraulic press used for metal forming invented by English engineer Joseph Bramah. The principle was first outlined by Pascal 150 years earlier.

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.

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.

VOLTA

Alessandro Volta

Thee man who started it all.

Voltaic pile

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 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. 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.

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 Robert 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 practised 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 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:

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 Mark Isambard Brunel, father of famous son Isambard Kingdom Brunel, with the task of manufacturing 60,000 wooden pulley blocks per year, set up one of the first ever mass production lines. Instead of one man making a complete pulley Brunel divided the work into a series of simple, short cycle, repetitive tasks and using 43 purpose-built precision machines from Maudslay to carry out the sequential operations in line, he reduced the labour required to do the work from 110 to 10. A formula which has become an industry standard.

1809 Davy produced an electric arc between two Carbon electrodes - the first electric light. 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."

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.

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 queueing 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. 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.

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 (1922) and Jedlik (1928).

This invention was the source of a bitter controversy with Humphry Davy and William Hyde Wollaston 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 a humble man with no formal education who 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 provided 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.

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:

where η is the maximum efficiency which can be achieved by the energy conversion, T_h is the input (hot) temperature of the working fluid in degrees Kelvin and T_c 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.

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 To view electrical discoveries in the context of other key events in the Industrial Revolution, it was in this year that 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. Five years later in 1930 Stephenson's Rocket was successful at the Rainhill Trials and was adopted as the engine for the new Liverpool Manchester railway starting 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.

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.

1829 Nobili 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)

1831 Faraday 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.

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.

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 new to his father Mark 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. 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 sufficent advantage on the score of economy of fuel can be obtained", and the project was abandonned.

1833 Undeterred by the experience of the Brunels (see 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 which he patented in 1836 (though earlier designs by Scottish inventors Steadman (1816) and Wilson (1827) and others existed but had not been patented). But discredited by his failure to demonstrate the benfits 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 he left Britain in 1839 for the USA where he continued to work on the caloric engine for 20 years. Though he sold may examples, 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 V_i and the final volume V_f)

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 of Ampère'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 41and 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".

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 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".

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.

1837 Patent 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.

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 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.

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 manoeuvering 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:

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.

1841 The non-polarisng 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 staionary 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.

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.

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.

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 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").

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.

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.

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)

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.

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.

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, one of the greatest engineering feats of the nineteenth century, was completed. Financed by American entrepreneur Cyrus Field, it was designed and supervised by arrogant and incompetent amateur electrician Dr Edward Orange Wildman Whitehouse, a former surgeon from Brighton. Unfortunately the cable failed after less than a month in use, almost before the celebrations were complete, having transmitted only 732 messages. 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 in 1866 enhanced both his reputation and his bank balance as well as his already considerable ego.

It was not until 1956, almost a hundred years later, 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.

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.

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 configuation 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.

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 red, green and blue primary colours 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.

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 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 ITUs recognition of "the sovereign right of each State to regulate its telecommunication"

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 Charles Wheatstone 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 electrostaic 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 relaid 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 contunued to undergo many engineering impovements. 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 atmosphhere, 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.

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.

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.

In mathematical vector form these complex relationships can be expressed very simply as:-

Where
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.

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 it.

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 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.

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.

Maxwell died of stomach cancer in 1879 at the age of forty eight without seeing the experimental confirmation of his theories.

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. 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.

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).

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.

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 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.

Non polarising 2 Volt primary cells were mostly based on potassium dichromate and often used two electrolyte gravity cells (See below). Examples were:

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

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:

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.

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.

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 The invention which did more than any other to promote the use of electricity in the home, the electric light bulb was patented by Thomas Alva Edison. In the early years however the only source of domestic electrical energy generally available was the battery and so all the development took place using DC/battery power.

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 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.

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.

Despite the unfortunate ending to their previous relationship, in 1877 Edison was hired once more by William Orton the head of Western Union 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 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 story of the light bulb is a re-run of the telegraphy and telephony stories, intrigues destined to be repeated with radio, computers, the internet and each new technology advance.

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 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.

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.

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 central electricity generating plants or power stations were completed by the Edison Electric Lighting Company. 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.

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 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 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") 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 1896 Arrhenius was 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 toroid. 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.

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 Heroult and is now called the Hall-Heroult 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.

1886English 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 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.

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 Max Planck.

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.

The demand for batteries of course benefited from all of these new developments.

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 verically. 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 dialing, which required the caller to provide the pulses by tapping on the keys.

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 (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 B_max 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 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 investgated variations of the coherer effect observed when loosely compacted particles or lightly touching objects were subject to electrical or magnetic fields.

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.

1892 The Hayes patent paved the way for telephone signalling and speech to be powered from a single large central 24 Volt lead acid batteries mounted in central telephone exchanges, eliminating the need for magnetos and Leclanché cells installed in every subscriber's premises. The system is still in use today.

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:

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 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).

1894 British engineer Charles Algernon Parsons had produced his first steam turbine in 1885 but had failed to generate any commercial interest in it. 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.

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. 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 while investigating the glow from the cathode rays and 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. 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 the first application of radio waves and he was the first to show that radio communications were possible. His system however was the radio equivalent of Morse's telegraph, switching the radio wave on and off in "dots and dashes", and it did not carry voice signals. 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.

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.

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.

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 April1897. 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 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 = IⁿT 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.

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 recogising 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 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.

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 hν where h is a universal constant equal to 6.63 X 10^-34 Joule seconds (Js), now called Planck's constant.

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 rechargeable Nickel 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.

1903 The 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 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 multilayer 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.

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 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 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 an 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.

Fessenden 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.

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. Pickard typically 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.

1908 Construction of the first German pumped 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 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 Superconductivity was first observed in mercury by Dutch physicist Heike Kamerlingh Onnes of Leiden University. When he cooled it to the temperature of liquid helium, 4 degrees Kelvin, its resistance suddenly disappeared.

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 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 brighness, 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 redshift of light spectra from distant galaxies to the American Astronomical Society showing that out of 15 galaxies, 11 were clearly redshifted. 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 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 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 ciircuits, 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 spectrgraphic 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.

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.

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.

Battery and Energy Technologies

History of Batteries (and other things)

Heroes and Villains - A little light reading