Alessandro Guiseppe Antonio Anastasio Volta
Alessandro Guiseppe Antonio Anastasio Volta (b. Como, Italy, 18th Feb.1745, d. Como, Italy, 5th March 1827) was a pioneer in the field of electricity. The SI unit of electric potential was named after him as the Volt. The portrait (above) was featured on the Italian 10,000 Lire banknote. He came from a Lombard family ennobled by the municipality of Como and almost extinguished, in his time, through its service to the church. One of his paternal uncles was a Dominican, another a Canon and the third an Archdeacon. His father, Filipo (1862-1752), after eleven years as a Jesuit, withdrew to propagate the line. Filipo married Maddelena de' conti Inzaghi in 1773. They had seven children; three girls, two of whom became nuns; three boys who followed the careers of their uncles; and Alessandro, the youngest.
Alessandro was about seven when his father died. His uncle the Canon took charge of his education. Alessandro joined the local Jesuit College in 1757. His quickness soon attracted the attention of his teachers. In 1761 the philosophy professor, Girolamo Bonensi, tried to recruit him. This made his uncle want to take him from school. Volta continued his education at Seminario Benzi. His uncle wanted him to be an attorney. But, Volta chose the study of electricity.
Alessandro was a large, vigorous man. He actively practised the Catholic faith. He, in the words of his friend Lichtenberg, "understood a lot about the electricity of women." For many years he enjoyed the favours of a singer, Marianna Paris, whom he might have married but for his theological and family opinion.
Volta developed the concept of 'state of saturation of bodies' to explain attractions and repulsions of electrified bodies. The electrophore he invented was severely criticized by Beccaria, one of the chief authorities in electricity. In 1774, he became the principal of the state Gymnasium in Como. In 1775, he was granted the professorship of experimental physics. Cavendish's memoir of 1771 made Volta transform his notion of 'natural saturation' into the concept of potential. His last memoir was on galvanic and common electricity. Seeing Volta's demonstrations, Napoleon raised him to Count and Senator of the kingdom of Italy. During the last 20 years of his life he had the income of a wealthy man.
André-Marie Ampére (b. Lyons, France, 22nd Jan. 1775, d. Marseilles, France, 10th June 1836) was a mathematician, a chemist, a physicist and a philosopher. The SI unit of electric current was named after him as the Ampere. His father, Jean-Jacques, was a merchant. Jean-Jacques exposed his son to a library and let him educate himself according to his own tastes. André-Marie soon discovered and perfected his mathematical talents. He even learned Latin in order to read the works by Euler and Bernoulli. The great encyclopédie had the most important influence on him. He was also thoroughly instructed in Catholic faith. During the French Revolution, his father was guillotined. André-Marie was unable to bear this shock. For a year, he retreated, not talking to anyone. During this time, he met Julie Carron who was somewhat older than he was. Ampére pursued Julie until she consented to marry him. They were wed on the 7th of August 1799 and their son, Jean-Jacques, was born.the following year. Ampére became the professor of physics and chemistry at the École-Centrale of Bourgen-Bresse, where he worked on probability theory. Julie died on the 13th of July 1803 of an illness. Ampére became inconsolable again. He married Jeanne Potot in 1806. After the birth of their daughter, Albine, they got a divorce.
Between 1820 and 1825, after a series of experiments, Ampére provided factual evidence for his contention that magnetism was electricity in motion, summarized in his famous 9 points. They describe the law of action of current carrying wires, and model magnets as having circulating currents in them. Ampére was able to unify the fields of electricity and magnetism on a basic numeric level. Fresnel helped Ampére improve his theory by suggesting that there may be currents of electricity around each molecule. Ampére assumed that the 'electrodynamic molecule' was a molecule of iron that decomposed the aether, that pervaded both space and matter into the two 'electric fluids.' Ampere's theory of the electrodynamic molecule was not accepted by everyone. His primary opponent was Michael Faraday, who could not follow the mathematics and did not accept his theory. Ampére's son fell in love with Mrs. Jeanne Recamier, an entertainer and a great beauty of the empire. His daughter Albine, married an army officer who turned out to be a drunkard. Following this, after 1827, Ampére's scientific activity declined and he died alone, while on a tour in Marseilles.
James Prescott Joule
James Prescott Joule (b. Salford, England, 24th Dec. 1818, d. Salford, England, 11th October 1889) was the second son of a prosperous brewer. The SI Unit of energy or work was named after him as the Joule. James was not a strong child. He had a spinal injury which left a slight deformity. Because of this, his education was limited. To a large extent he was self taught. He even read relatively little and had no pretence of being a great scientist. When he was 16, he and his brother, Benjamin, studied under Dalton for about two years. His chief contact with the world was with the members of the Manchester Literary and Philosophical Society. He began his quantitative electrical work when he was 19, using a standard resistance of copper wire.
He was a simple, earnest and modest man. He was the first to give an expression for the heat generated in a resistor by current flow, in 1840, and to observe magnetostriction. He spent a major part of his life working on the mechanical equivalence of heat. In 1845, he investigated the relationship between the temperature and the internal energy of gas. In April 1847, he gave a popular lecture in Manchester in which he stated the concept of the conservation of energy. But, it went unnoticed. At a meeting at Oxford in June 1847, he was advised by the chairman to restrict himself to a brief oral report on his experiments, rather than a paper, and not to invite discussion. Fortunately, his idea was grasped by William Thomson, Faraday and Stokes. Recognition to Joule came from Faraday who introduced Joule's 1849 paper to the Society. This paper won for him the 1852 Royal Medal. His last remarkable contribution was work in 1860 which resulted in a significant improvement of steam-engine efficiency. In the same year, he made one of the first accurate galvanometers and calibrated it by use of a voltmeter. He received many awards and medals including the 1870 Copley Medal and a pension from the queen in 1878.
His mother died in 1836. His father retired in 1883 due to illness. James and Benjamin took over the family brewing. James married in 1847 and had a daughter and a son. After the death of his wife in 1854, the brewery was sold. Joule's health became worse as time passed. He suffered from frequent nose-bleeding, presumably haemophilia. But, he kept on working as much as he could until his death.
Georg Simon Ohm
Georg Simon Ohm (b. Erlangen, Germany, 16th March 1789, d. Munich, Germany, 6th July 1854) was a mathematician and a physicist. The SI unit of electrical resistance was named after him as the Ohm. His father, Johan Wolfgang Ohm, was a master locksmith. Johan Wolfgang married Maria Elizabeth Beck, daughter of a master tailor. They were a protestant couple. Of their seven children only three survived childhood: Georg Simon the eldest, Martin the mathematician, and Elizabeth Barbara. Johan Wolfgang gave his sons a solid education in mathematics, physics, chemistry and the philosophies of Kant and Fichte. Their mathematical talents were soon recognised by the Erlangen professor Karl Christian Von Langsdorf. Georg Simon matriculated on the 3rd of May 1805 at the University of Erlangen. He studied 3 semesters there until his father's displeasure at his supposed overindulgence in dancing, billiards, and ice skating forced him to withdraw to rural Switzerland.
He began to teach mathematics in September 1806 in Gottstadt. He received his PhD on the 25th of October 1811. Lack of money forced him to seek employment from the German government. But, the best he could obtain was a post as a teacher of mathematics and physics at a poorly attended 'Realschule' in Bamberg. He worked there with great dissatisfaction. In 1817, Ohm was offered the position of 'Oberlehrer' of mathematics and physics at the Jesuit Gymnasium at Cologne. He began his experiments on electricity and magnetism after 1820. His first scientific paper was published in 1825 in which he sought a relationship between the decrease in the force exerted by current-carrying wires and the length of the wires. In April 1826, he published two important papers on galvanicm electricity. He published his book on Ohm's law, Die Galvanische Kette Mathematische Bearbeit, in 1827. Sir John Leslie had already provided both theoretical discussion and experimental confirmation of Ohm's law in a paper written in 1791 and published in 1824, which was not accepted. Ohm's law was so coldly received that Ohm resigned his post at Cologne. Ohm obtained the professorship of physics at the Polytechninische Schedule in Nuremberg in 1833. Finally, his work began to be recognised. In 1841, he was awarded the Copley Medal of the Royal Society of London and was made a foreign member a year later.
Charles William Siemens
Charles William Siemens (ne: Carl Wilhelm Siemens, b. Lenthe, Germany, 4th April 1823, d. London, England, 9th November 1883) was a pioneer in the practical application of scientific discoveries to industrial processes. The SI unit of electrical conductance was named after him as the Siemens (S). Christian Ferdinand Siemens, a wealthy farmer, and his wife, Eleonore Deichmann had eleven sons and three daughters, of whom Charles William was the seventh child. In July 1839, Eleonore died. Unable to bear this loss, Ferdinand died six months later. A few years later, the children were dispersed among relations and friends.
Siemens went to England in 1843. Being a shrewd businessman, he sold the patent of the electroplating invention of his elder brother, Werner. William was naturalised as a British subject on the 19th of March 1859. On the 23rd of July he same year, he married Anne Gordon. Siemens Brothers, founded in 1865 by William and Werner, soon became a world famous manufacturer of telegraphic equipment, cables, dynamos and lighting equipment. William was a member of the Society of Telegraph Engineers; the British Association, the Institution of Civil Engineers, and the Institute of Mechanical Engineers and a fellow of the Royal Society. He developed a highly successful meter for measuring water consumption. His important invention of the regenerative gas furnace and its application to open-hearth steel making and other industrial processes made him independently wealthy before 1870. In 1874, he designed the cable ship 'Faraday' and assisted in the laying of the first of several transatlantic cables. During the last 15 years of his life he actively supported the development of the engineering profession and stimulated public interest in the reduction of air pollution and the potential value of electric power in a wide variety of engineering applications.
Suffering an acute pain in the region of the heart for a few weeks, he was attacked by a difficulty of breathing. As he was sitting in his arm chair, peacefully and quietly, as if he were falling asleep, his spirit passed away. The burial took place on the 26th of November, followed by a very grand funeral service. As he had requested, the inscription on his coffin contained simply his name. The Institute of Civil Engineers erected a stained glass window in Westminster Abbey as a tribute of respect in his memory.
Charles-Augustin Coulomb (b. Angouleme, France, 14th June 1736, d. Paris, France, 23rd August, 1806) was a pioneer in the field of electricity, magnetism and applied mechanics. The SI unit of quantity of electric charge was named after him as the Coulomb. In his electrical studies Coulomb determined the quantitative force law, gave the notion of electric mass, and studied charge leakage and the surface distribution of charge on conducting bodies. In magnetism he determined the quantitative force law, created a theory of magnetism based on molecular polarisation, and introduced the idea of demagnetisation.
His father, Henrey, came from Montpellier, where the family was important in the legal and administrative history of Languedoc. His mother, Catherine Bajet, was related to the wealthy de Senac family. During Charles-Augustin's youth the family moved to Paris. Charles-Augustin attended lectures at the College Mazarin and the College de France. An argument with his mother over career plans caused Coulomb to follow his father to Montpellier who became penniless later through financial speculations.
Coulomb graduated in November 1761 with the rank of lieutenant en premier in the Corps du Génie. He worked at Brest and then at Martinique. While he was in Martinique he became seriously ill several times. The research he did in Richefort won him the double first prize at the academy in Paris in 1781. He became a resident in Paris. He found a wife there and raised a family. He wrote 25 scientific Momoirs at the Academy from 1781 to 1806. He also participated in 310 committee reports to the Academy. In 1787 Coulomb was sent to England to investigate hospital conditions in London. In 1801 he was elected to the position of the president of the Institute de France. By 1791, the National Assembly reorganized the Corps du Génie. Coulomb had to resign from the corps. He received an annual pension which was reduced by two-thirds after the Revolution. He returned to his research in Paris in December 1795, upon his election as member for physique experiméntale in the new Institute de France. Coulomb's last public service was as inspector general of public instruction from 1802 until his death. Coulomb's health declined precipitously in the early summer of 1806 and he died. Secondary accounts indicate that Revolution took most of his properties and that he died almost in poverty.
Michael Faraday (b. Newington, Surrey, England, 22nd Sep. 1791, d. Hampton Court, Middlesex, England, 25th August 1867) was a physicist, a chemist, a physical chemist and a natural philosopher. The SI unit of capacitance was named after him as the Farad (F). He was born into a poor family, of which he was he third of four children. His father, James Faraday, was a blacksmith. James Faraday's poor health prevented him from providing more than bare necessities to his family. Michael later recalled that he was once given a loaf of bread to feed him for a week. His parents were members of the Sandemanian Church, and Michael was brought up within this discipline. His most favourite book was the Bible in which he had heavily underlined, Timothy 6:10, "The love of money is the root of all evil." Michael, at the age of 14, was apprenticed to Riebau, a bookseller and a bookbinder, in whose shop he read books on science that came to his hands.
In 1812, one of the customers at Riebau's shop, gave Faraday a ticket to attend the last four lectures of a course given by Humphry Davy at the Royal Institution of Great Britain. He applied to Davy for employment, sending him as evidence of his interest the notes that he had made of his lectures. At the age of 21, he was appointed assistance to Davy to help with both lecture experiments and research. He accompanied Davy on a tour in Europe where he saw much of the active scientific research. In 1821, he married Sarah Barnard, a union that was happy though childless. Faraday became the discoverer of electromagnetic induction, of the laws of electrolysis, and of the fundamental relations between between light and magnetism. He was the originator of the conceptions that underlie the modern theory of the electromagnetic field. He also discovered two unknown chlorides of carbon and a new compound of carbon. His last discovery was the rotation of the plane of polarization of light in magnetic field. When Faraday was endeavouring to explain to the Prime Minister or to the Chancellor of the Exchequer an important discovery, a politician's alleged comment was, "But, after all, what use is it?" Whereupon Faraday replied, "Why sir, there is a probability that you will soon be able to tax it!" His mind deteriorated rapidly after the mid-1850s. In 1862, he resigned his position at the Royal Institution, retiring to a house provided for him by Queen Victoria at Hampton Court.
Joseph Henry (b. Albany, NY, USA, 17th December 1797, d. Washington, USA, 13th May 1878) was a pioneer in the field of electromagnetism. The SI unit of inductance was named after him as the Henry (H). He was born to a poor family of Scottish descent and raised as a Presbyterian, a faith he followed throughout his life. His elementary education was in Albany and Galway, New York, where he stayed with relatives. Henry was apprenticed to an Albany watchmaker and silversmith. The theater was his principal interest as an adolescent, until a chance reading of George Gregory's Popular Lectures on Experimental Philosophy, Astronomy, and chemistry turned him to science. In 1819 he enrolled in the Albany Academy and remained there until 1822, with a year off to teach in a rural school in order to support himself. He did odd surviving jobs while he was doing his scientific research. in 1825, Henry was appointed professor of mathematics and natural philosophy at the Albany Academy. In 1832, he accepted a chair at the College of New Jersey.
Henry's earliest known work was in chemistry. In 1827, he started active research on electricity and magnetism. Throughout his career, Henry was interested in terrestrial magnetism and other geophysical topics. He independently uncovered the sense of Ohm's law and engaged in impedance matching. In 1832, Henry discovered self-inductance following some experiments. He also conducted investigations on capillarity, phosphorescence, heat, colour blindness and the relative radiation of solar spots with skill and imagination. His 1835 paper was on the action of a spiral conductor in increasing the intensity of galvanic currents. He conceived of astronomy as the model science and mechanics as the ultimate analytical tool. Henry could not accept Faraday's field concept because of his belief in central forces acting in a universal fluid. He concluded that the currents are oscillatory wave phenomena exciting equivalent effects in an electrical plenum coincident, if not identical, with the universal aether.
Henry formed the Smithsonian Committee, consisting of dedicated men forming internationally recognized standards and engaging in free and harmonious intellectual intercourse among themselves. Being the secretary of the Smithsonian, he was not interested in popularizing science but with supporting research and disseminating findings.
Nicola Tesla (b. Smiljan, Croatia, 10th July 1856, d. New York 7th Jan. 1943) was a pioneer in the field of high-tension electricity. The SI unit of magnetic flux density was named after him as the Tesla (T). He made many discoveries and inventions of great value to the development of radio transmission and to the field of electricity. These include a system of arc lighting, the Tesla induction motor and a system of alternating-current transmission, the Tesla coil, a transformer to increase oscillating currents to high potential, a system of wireless communication, and a system of transmitting electric power without wires. He designed the great power system at Niagara. Tesla's advanced concepts include transmission of large quantities of electrical power without wires and inexhaustible energy supplies from the universe. Despite over 700 patents bearing his name he disliked being called an "inventor," much preferring the description "discoverer."
He emigrated to United States in 1884 with the hope of finding a backer for his polyphase alternating current system. The magnet that drew him was the Niagara falls. As a boy in his teens he had seen a picture of the falls, ever since then the hope of converting the power of the falls into electricity had remained with him. It is said that when he thought of an object, he could see it physically and had no need of pencil and paper, just as when he read, which he did rapidly, he was virtually photographic.
When Edison heard his ideas he was not interested but gave him a job. Edison promised $50,000 if Tesla could perfect a new type of dynamo. When Tesla succeeded and asked for the money he was told that he did not understand American sense of humour. At this point Tesla quit. He was unemployed and was forced to dig ditches at $2 per day to earn a living. Fortunately his foreman introduced him to a Mr Brown of Westinghouse and once more he had a laboratory. Tesla continued on his invention and in May 1890, he was granted the first string of patents, and they grew faster. George Westinghouse offered one million dollars to Tesla for his patents. During the Spanish -American war Tesla offered to the government his invention of a "robot" to be operated by remote control by means of his wireless system. They laughed at him. He died a pauper leaving behind a golden legacy in the shape of his great inventions.
Wilhelm Eduard Weber
Wilhelm Eduard Weber (b. Wittenberg, Germany, 24th October 1804, d. Gottingen, Germany, 23rd June 1891) was one of the twelve children of Michael Weber, professor of theology at the University of Wittenberg. The family lived in the house of Christian August Langguth, a professor of medicine and natural history. The house was burned during the bombardment of Wittenberg by the Prussians in 1813. The following year the Webers settled in Halle. Wilhelm began his scientific work in collaboration with Ernest Heinrich at the University of Halle.
Wilhelm published his famous paper, which contained experimental investigations of water and sound waves, in 1825. In 1831, he became the professor of physics at Gottingen, where his friendship with Gauss began. In 1832, Weber introduced absolute units of measurements into magnetism. Gauss and Weber founded the Gottingen Magnetische Verenin to initiate a network of magnetic observations and to correlate the resulting measurements. In 1833, they set up a battery-operated telegraph line some 9,000 feet long, between the physics and
astronomical observatory, in order to facilitate simultaneous magnetic observations. Weber also managed to find time to work with his younger brother Eduard on the physiology and physics of human locomotion.
With the death of William IV in 1837, Victoria became the queen of England and her uncle, Ernst August, acceded to the rule of Hannover and at once revoked the liberal constitution of 1833. Weber was one of the seven Gottingen professors who signed a statement of protest. At the king's order all the seven lost their positions. But, Weber continued his research. In 1843, Weber became the professor of physics at Leipzig. There he formulated his law of electrical force, which was later discarded with the triumph of Maxwell's field theory. In 1848, he was able to return to his old position. Weber retired in 1870's, relinquishing his duties in physics to his assistant, Edward Rieche. Rieche, later began the development of electron theory of metals from Weber's ideas. Weber received many honours from Germany, France, and England, including the title of Geheimrat and the Royal Society's Copley Medal. The SI unit of magnetic flux was named after him as the Weber (Wb). Weber, a friendly, modest, and unsophisticated man, remained unmarried. He died peacefully in his garden.
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz (b. Hamburg, Germany, 22nd Feb. 1857, d. Bonn, Germany, 1st January 1894), a physicist, whose research has come to be regarded as the starting point of radio - it was he who first detected and measured electromagnetic waves in space. The SI unit of frequency was named after him as the Hertz (Hz). His grandfather, Heinrich David Hertz, the youngest son of a wealthy Jewish family was converted to the Lutheran faith along with his wife and children. David Heinrich Hertz's son, Gustav, became a Minister of Justice and was the first to attend a university in the family. He married a classmate's sister, Anna Elisabeth Pfefferkorn, and had five children, the eldest of whom was Heinrich Rudolf Hertz.
He was an exceptionally gifted child and excelled in every way. After completing his secondary education, he wanted to be a structural engineer and served as an apprentice in a civil engineering office. Reading a lot of books, he became interested in telegraphy and enrolled in the Technical University of Dresden. Finding the level of instruction low for him, after one semester, he embarked on his year of compulsory military service. He then enrolled in the Technical University of Munich to do physics, but later, switched to the University of Munich. He was still not satisfied, and after two semesters transferred to the University of Berlin where Gustav Kirchhoff and Hermann Helmholtz taught physics. Very soon he was working as a student assistant to Helmholtz. He graduated the following year, before which he had written two papers on his research - determining if electrons have inertial mass and induction in rotating spheres. He obtained his doctorate in 1880 and was appointed assistant of Helmholtz.
After three years, he went to the University of Kiel to become a lecturer in physics and soon he was promoted and became a professor at the Technical High School in Karlsruhe, and then he went to the University of Bonn. In 1886 he married Elizabeth Doll, and started his research on electric waves. He wrote many papers not only in electromagnetism but also in the theory of contact mechanics and the measurement of hardness. Suffering a severe illness which led to chronic blood poisoning he died after indescribable suffering. He was an extremely modest man and once denying the request for publishing his portrait he said, "... Too much honour certainly does me harm in the eyes of reasonable men..." and four years after, following his death, his portrait was published.
Guglielmo Marconi (b. Bologna, Italy, 25th April 1874, d. Rome, Italy, 20th July, 1937) was the second son of Giuseppe Marconi, a wealthy landowner, and his second wife, Annie Jameson, the daughter of an Irish Whiskey distiller. Giuseppe Marconi ruled his household in the style of a martinet. Guglielmo spent most of childhood away from home. Consequently, his education was neglected. When he was sent to a school, he was unable to cope with his studies and other students made fun of his poor Italian accent. He failed to pass the entrance examination to the Italian Naval Academy and went to Livorno Technical Institute. His ambition was to have an electrical career, but he could not even pass his matriculation. His father became very angry, wrecked the devices Guglielmo had constructed, and even withheld his pocket money. But, his mother did all she could to help her son do his experiments. Marconi did experiments on electromagnetic waves with the assistance of Prof. A. Righi of Bologna and discovered that increased transmission distance could be obtained with larger antennas. In 1895, he achieved a transmission distance of 1.5 miles, and also conceived of 'wireless telegraph' communication.
Being unable to interest the Italian Government in the potential of his work, he moved to London in 1896. His Irish cousin, Henry Jameson Davis, helped him to form and finance the Wireless Telegraph and Signal Co. Ltd., which became Marconi's Wireless Telegraph Co. Ltd. in 1900. On behalf of the Italian Government, Solari presented to Marconi a newly invented receiver. Having increased his signaling distance to 150 miles, using a kiteborne antenna and Solari's carbon-on-steel detector with a telephone receiver, on the 12th of December 1901, he received a transatlantic wireless communication, the three code dots signifying the letter 'S'. He became famous overnight. But, controversy arose when Prof. Angelo Banti pointed out that the receiver was actually invented by a corporal signalman, Paolo Castelli. After 1902, Marconi spent most of his time managing his companies. He was able to attract highly qualified employees including J. A. Fleming. In 1927, Marconi's company completed a system of shortwave beam stations. In 1932, he discovered that microwaves could be received at a point much farther below the optical horizon than had been predicted by any theory. Marconi received many awards including the Nobel Prize for physics, which he shared with K. F. Braun in 1909.
Gustav Robert Kirchhoff
Gustav Robert Kirchhoff (b. Konigsberg, Germany, 12th March 1824, d. Berlin, Germany, 17th October 1887) was a physicist. His father was a law councillor. Kirchhoff easily derived Kirchhoff's voltage law for electrical network analysis between 1845-1846, while he was still a student at Konigsberg. In 1849, following the experiments of Kohlrausch, he introduced Kirchhoff's current law for electrical network analysis. He graduated in 1847 and married Clara Richelot, the daughter of one of his teachers, the same year. Three years later, he was appointed professor at Breslau. In 1854, he moved to Heidelberg, where Robert Bunsen was a professor of chemistry. In 1869, Clara died, leaving him two sons and two daughters. In 1872, he married Luise Brommel.
In 1859, he published an explanation of the dark lines in the sun's spectrum, discovered by Josef von Fraunhofer. In the course of investigating the optical spectra of chemical elements, Kirchhoff made his major contribution to science which was his experimental discovery and theoretical analysis of a fundamental law of electromagnetic radiation which states that for all material bodies, the ratio of absorptive and emissive power of radiation is a universal function of wavelength and temperature. In 1860, Bunsen and Kirchhoff discovered that each chemical substance emits light that has its own unique pattern of spectral lines. A Few months later, they discovered a new metal, cesium and the next year, they found rubidium. They also constructed an improved form of the spectroscope. Kirchhoff once told his bank manager of the discovery of terrestrial metals of the sun. The bank manager said, "Of what use is gold on the sun if I cannot get it down to earth?" later, after Queen Victoria of England had presented Kirchhoff with a medal and a prize in gold sovereigns for work on the sun's spectrum, he took them to the bank manager and said, "Here is some gold from the sun!"
Kirchhoff was crippled by an accident in mid-Iife which compelled him to use crutches and wheelchair. But, he remained in good spirit. On two occasions he turned down calls to other universities. Only when his failing health hindered his experimental work did he accept a chair of theoretical physics offered to him in Berlin. He worked there with great devotion, until illness forced him to give up his teaching activity in 1886. He bore with patience the long illness of his last years. He died peacefully, presumably of a cerebral congestion.
Léon Charles Thévenin
Léon-Charles Thévenin (b.Meaux, France, 30th March 1857, d. Paris, 1926) was a French telegraph engineer and educator. He was the one to propose the equivalent generator theorem in 1883, 43 years before Norton's complementary theorem. The theorem is commonly called Thévenin's Theorem in his honour, but, in fact Hermann Von Helmholtz proposed it first in an 1853 paper.
Thevenin graduated from the École Polytechnique in 1876 and became one of the first students to enrol in the École Superieure de Telegraphie (EST) to be prepared for a career in the Government owned telegraph service. In the two-year program at the EST, he was introduced to Gustav Kirchhoff's laws of circuit analysis. His duties included administrative and educational activities. Thévenin devoted a considerable portion of his time to teaching, for which he had a liking. In connection with his teaching, he undertook an investigation of Kirchhoff's laws as applied to electric networks. This study resulted in his formulation of the equivalent generator theorem.
He was a talented violin player. Another favourite pastime of his was angling. He remained single but shared his home with a widowed cousin of his mother's and her two children whom he later adopted.
Thévenin consulted several scholars well known at that time, and controversy arose as to whether his law was consistent with the facts or not. Shortly before his death he was visited by a friend of his, J. B. Pomey, and was surprised to hear that his theorem had been accepted all over the world.
In 1926, he was taken to Paris for treatment. He left a formal request that no one should accompany him to the cemetery except his family and that nothing be placed on his coffin but a rose from his garden. This is how he was buried at Meaux. Thévenin is remembered as a model engineer and employee, hard-working, of scrupulous morality, strict in his principles but kind at heart.
Edward Lawry Norton
Edward Lawry Norton (b. Rockland, Maine, USA, 28th July 1898, d. Chatham, New Jersey, USA, 28th January1983) was an American electrical engineer for whom the Norton equivalent circuit is named.
Norton served as a radio operator in the U.S Navy between 1917 and 1919. He attended the University of Maine for one year before and for one year after his wartime service, then transferred to MIT in 1920, receiving his BS degree in electrical engineering in 1922. He started work in 1922 at the Western Electric Corporation in New York City, which eventually became Bell Laboratories in 1925. While working for Western Electric, he earned an MA degree in electrical engineering from Columbia University in 1925.
Among his publications are constant resistance networks with applications to filter groups in the Bell System Technical Journal, magnetic fluxmeter in the Bell Laboratories Record and dynamic measurements on electromagnetic devices in the Transactions of the AIEE. Norton wrote 92 technical memoranda (TMs in Bell Laboratories parlance). Because of Norton's lack of publications, it appears that Norton preferred working behind the scenes. As described in the history of Bell Labs, "this reticence belied his capabilities."
Norton was something of a legendary figure in network theory work who turned out a prodigious number of designs armed only with a slide rule and his intuition. Many anecdotes survive. On one occasion T.C. Fry called in his network theory group, which included at that time Bode, Darlington and R.L. Dietzold among others, and told them: "You fellows had better not sign up for any graduate courses or other outside work this coming year because you are going to take over the network design that Ed Norton has been doing single-handed." [A History of Engineering and Science in the Bell System: Transmission Technology (1925-1975), p. 210]
He applied his deep knowledge of circuit analysis to many fields, and after World War II he worked on Nike missile guidance systems. On November 11, 1926, he wrote the technical memorandum Design of Finite Networks for Uniform Frequency Characteristic, that contains the following paragraph on page 9:
"The illustrative example considered above gives the solution for the ratio of the input to output current, since this seems to be of more practical interest. An electric network usually requires the solution for the case of a constant voltage in series with an output impedance connected to the input of the network. This condition would require the equations of the voltage divided by the current in the load to be treated as above. It is ordinarily easier, however, to make use of a simple theorem which can be easily proved, that the effect of a constant voltage E in series with an impedance Z and the network is the same as a current I=E/Z into a parallel combination of the network and the impedance Z. If, as is usually the case, Z is a pure resistance, the solution of this case reduces to the case treated above for the ratio of the two currents, with the additional complication of a resistance shunted across the input terminals of the network. If Z is not a resistance the method still applies, but here the variation of the input current E/Z must be taken into account."
This paragraph clearly defines what is now known as the Norton equivalent circuit in the United States. Norton never published this result or mentioned it in any of his 18 patents and 3 publications. In Europe, it is known as the Mayer-Norton equivalent. The German telecommunications engineer Hans Ferdinand Mayer published the same result in the same month as Norton's technical memorandum. Norton retired in 1961 and died on January 28, 1983 at the King James Nursing Home in Chatham, New Jersey.
Report (2) (0) |
4 years, 6 month(s) ago