Battery History, Technology, Applications and Development

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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 writen 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 picofarads 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.

350 B.C. The Greek philosopher and scientist Aristotle (384-322 B.C.) provided "scientific" theories based on pure "reason" for everything from the 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.

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.

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.

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 buillt 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 Chinese astronomer, cartographer and mathematician Shen Kua, in his Dream Pool Essays, describes the compass and its use for navigation and cartography as well as 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 eachother. 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.

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.

Gilbert was the English champion of the experimental method of scientific discovery considered inferior by the Greek philosopher Aristotle and his followers who believed that knowledge should be obtained by pure thought hampering scientific progress for over 2000 years. In support of Aristotle 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 Galileo's time that instruments such as microscopes, telescopes, clocks with minute hands, thermometers and manometers started to become available.

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.

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.

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

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 Accademia 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 eachother, and there was no standardised scale in use.

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 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, called the aerometer by the Greeks, is however considered to be the invention of Hypatia head of the Platonist school at Alexandria in about 400 A.D. where she lectured on mathematics and philosophy. Unfortunately she was killed by a Christian mob who at the time equated science with paganism.

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 eachother 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 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 od 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 glassworking 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.

1738 Swiss mathematician Daniel Bernoulli showed that Newtons 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 travelling 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.

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 eachother, 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.

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 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. 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.

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 eachother. 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.

Charle's 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.

1795 The hydraulic press used for metal forming invented by English engineer Joseph Bramah.

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, discoverer of oxygen and part time tax collector, 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.

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.

1803 Johann Wilhelm Ritter, a German physicist, 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.

In 1801 after studying the discovery of infrared radiation the previous year by German born English astronomer, Frederick William Herschel, Ritter discovered the ultraviolet region of the spectrum.

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.

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 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.

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 Napol

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