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1 Gramme, Zénobe Théophile
[br]b. 4 April 1826 Jehay-Bodignée, Belgiumd. 20 January 1901 Bois de Colombes, Paris, France[br]Belgian engineer whose improvements to the dynamo produced a machine ready for successful commercial exploitation.[br]Gramme trained as a carpenter and showed an early talent for working with machinery. Moving to Paris he found employment in the Alliance factory as a model maker. With a growing interest in electricity he left to become an instrument maker with Heinrich Daniel Rühmkorff. In 1870 he patented the uniformly wound ring-armature dynamo with which his name is associated. Together with Hippolyte Fontaine, in 1871 Gramme opened a factory to manufacture his dynamos. They rapidly became a commercial success for both arc lighting and electrochemical purposes, international publicity being achieved at exhibitions in Vienna, Paris and Philadelphia. It was the realization that a Gramme machine was capable of running as a motor, i.e. the reversibility of function, that illustrated the entire concept of power transmission by electricity. This was first publicly demonstrated in 1873. In 1874 Gramme reduced the size and increased the efficiency of his generators by relying completely on the principle of self-excitation. It was the first practical machine in which were combined the features of continuity of commutation, self-excitation, good lamination of the armature core and a reasonably good magnetic circuit. This dynamo, together with the self-regulating arc lamps then available, made possible the innumerable electric-lighting schemes that followed. These were of the greatest importance in demonstrating that electric lighting was a practical and economic means of illumination. Gramme also designed an alternator to operate Jablochkoff candles. For some years he took an active part in the operations of the Société Gramme and also experimented in his own workshop without collaboration, but made no further contribution to electrical technology.[br]Principal Honours and DistinctionsKnight Commander, Order of Leopold of Belgium 1897. Chevalier de la Légion d'honneur. Chevalier, Order of the Iron Crown, Austria.Bibliography9 June 1870, British patent no. 1,668 (the ring armature machine).1871, Comptes rendus 73:175–8 (Gramme's first description of his invention).Further ReadingW.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 30, pp. 377–90 (an extensive account of Gramme's machines).S.P.Thompson, 1901, obituary, Electrician 66: 509–10.C.C.Gillispie (ed.), 1972, Dictionary of Scientific Biography, Vol. V, New York, p. 496.GWBiographical history of technology > Gramme, Zénobe Théophile
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2 Davenport, Thomas
SUBJECT AREA: Electricity[br]b. 9 July 1802 Williamstown, Vermont, USAd. 6 July 1851 Salisbury, Vermont, USA[br]American craftsman and inventor who constructed the first rotating electrical machines in the United States.[br]When he was 14 years old Davenport was apprenticed to a blacksmith for seven years. At the close of his apprenticeship in 1823 he opened a blacksmith's shop in Brandon, Vermont. He began experimenting with electromagnets after observing one in use at the Penfield Iron Works at Crown Point, New York, in 1831. He saw the device as a possible source of power and by July 1834 had constructed his first electric motor. Having totally abandoned his regular business, Davenport built and exhibited a number of miniature machines; he utilized an electric motor to propel a model car around a circular track in 1836, and this became the first recorded instance of an electric railway. An application for a patent and a model were destroyed in a fire at the United States Patent Office in December 1836, but a second application was made and Davenport received a patent the following year for Improvements in Propelling Machinery by Magnetism and Electromagnetism. A British patent was also obtained. A workshop and laboratory were established in New York, but Davenport had little financial backing for his experiments. He built a total of over one hundred motors but was defeated by the inability to obtain an inexpensive source of power. Using an electric motor of his own design to operate a printing press in 1840, he undertook the publication of a journal, The Electromagnet and Mechanics' Intelligencer. This was the first American periodical on electricity, but it was discontinued after a few issues. In failing health he retired to Vermont where in the last year of his life he continued experiments in electromagnetism.[br]Bibliography1837, US patent no. 132, "Improvements in Propelling Machinery by Magnetism and Electromagnetism".6 June 1837 British patent no. 7,386.Further ReadingF.L.Pope, 1891, "Inventors of the electric motor with special reference to the work of Thomas Davenport", Electrical Engineer, 11:1–5, 33–9, 65–71, 93–8, 125–30 (the most comprehensive account).Annals of Electricity (1838) 2:257–64 (provides a description of Davenport's motor).W.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 28, pp. 263–4 (a short account).GW -
3 Holmes, Frederic Hale
[br]fl. 1850s–60s[br]British engineer who pioneered the electrical illumination of lighthouses in Great Britain.[br]An important application of the magneto generator was demonstrated by Holmes in 1853 when he showed that it might be used to supply an arc lamp. This had many implications for the future because it presented the possibility of making electric lighting economically successful. In 1856 he patented a machine with six disc armatures on a common axis rotating between seven banks of permanent magnets. The following year Holmes suggested the possible application of his invention to lighthouse illumination and a trial was arranged and observed by Faraday, who was at that time scientific adviser to Trinity House, the corporation entrusted with the care of light-houses in England and Wales. Although the trial was successful and gained the approval of Faraday, the Elder Brethren of Trinity House imposed strict conditions on Holmes's design for machines to be used for a more extensive trial. These included connecting the machine directly to a slow-speed steam engine, but this resulted in a reduced performance. The experiments of Holmes and Faraday were brought to the attention of the French lighthouse authorities and magneto generators manufactured by Société Alliance began to be installed in some lighthouses along the coast of France. After noticing the French commutatorless machines, Holmes produced an alternator of similar type in 1867. Two of these were constructed for a new lighthouse at Souter Point near Newcastle and two were installed in each of the two lighthouses at South Foreland. One of the machines from South Foreland that was in service from 1872 to 1922 is preserved in the Royal Museum of Scotland, Edinburgh. A Holmes generator is also preserved in the Science Museum, London. Holmes obtained a series of patents for generators between 1856 and 1869, with all but the last being of the magneto-electric type.[br]Bibliography7 March 1856, British patent no. 573 (the original patent for Holmes's invention).1863, "On magneto electricity and its application to lighthouse purposes", Journal of the Society of Arts 12:39–43.Further ReadingW.J.King, 1962, in The Development of Electrical Technology in the 19th Century; Washington, DC: Smithsonian Institution, Paper 30, pp. 351–63 (provides a detailed account of Holmes's generators).J.N.Douglas, 1879, "The electric light applied to lighthouse illumination", Proceedings of the Institution of Civil Engineers 57(3):77–110 (describes trials of Holmes's machines).GW -
4 Page, Charles Grafton
[br]b. 25 January 1812 Salem, Massachusetts, USAd. 5 May 1868 Washington, DC, USA[br]American scientist and inventor of electric motors.[br]Page graduated from Harvard in 1832 and subsequently attended Boston Medical School. He began to practise in Salem and also engaged in experimental research in electricity, discovering the improvement effected by substituting bundles of iron wire for solid bars in induction coils. He also created a device which he termed a Dynamic Multiplier, the prototype of the auto-transformer. Following a period in medical practice in Virginia, in 1841 he became one of the first two principal examiners in the United States Patent Office. He also held the Chair of Chemistry and Pharmacy at Columbian College, later George Washington University, between 1844 and 1849.A prolific inventor, Page completed several large electric motors in which reciprocating action was converted to rotary motion, and invested an extravagant sum of public money in a foredoomed effort to develop a 10-ton electric locomotive powered by primary batteries. This was unsuccessfully demonstrated in April 1851 on the Washington-Baltimore railway and seriously damaged his reputation. Page approached Thomas Davenport with an offer of partnership, but Davenport refused.After leaving the Patent Office in 1852 he became a patentee himself and advocated the reform of the patent procedures. Page returned to the Patent Office in 1861, and later persuaded Congress to pass a special Act permitting him to patent the induction coil. This was the cause, after his death, of protracted and widely publicized litigation.[br]Bibliography1867, History of Induction: The American Claim to the Induction Coil and itsElectrostatic Developments, Washington, DC.Further ReadingR.C.Post, 1976, Physics, Patents and Politics, New York (a biography which treats Page as a focal point for studying the American patent system).——1976, "Stray sparks from the induction coil: the Volta prize and the Page patent", Proceedings of the Institute of Electrical Engineers 64: 1,279–86 (a short account).W.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 28.GW -
5 Jablochkoff, Paul
[br]b. 14 September 1847 Serdobsk, Russiad. April 1894 St Petersburg, Russia[br]Russian military engineer and inventor of an electric "candle", the invention of which gave an immense impetus to electric lighting in the 1870s.[br]Jablochkoff studied at the Military Engineering College in St Petersburg. Having a scientific bent, he was sent to the Military Galvano Technical School. At the end of his military service in 1871 he was appointed Director General of the Moscow-Kursk telegraph lines for the Midi Railway Company. At this time he began to develop an interest in electric lighting, and in 1875 he left the Imperial Telegraph Service to devote his time exclusively to scientific pursuits. He found employment at the workshop of M Bréguet in Paris, where Gramme dynamos and Serrin arc lamps were being constructed. After some experimentation he found a means of producing a carbon arc that regulated itself without any mechanism. This lamp, the Jablochkoff candle, with two carbon rods placed parallel to each other and so close that an arc formed at the ends, could continue to burn until the rods were consumed. Plaster of Paris was used to separate the two electrodes and crumbled away as the carbon burned, thus exposing fresh carbon. These lamps were used in May 1878 in Paris to illuminate the avenue de l'Opéra, and later in Rome and London, and in essence were the first practical electric street lighting. Since there was no regulating mechanism, several candles could be placed in a single circuit. Despite inherent defects, such as the inability to restart the lamps after they were extinguished by wind or interruption of supply, they remained in use for some purposes for several years on account of their simplicity and cheapness. In 1877 Jablochkoff obtained the earliest patent to employ transformers to distribute current in an alternating-current circuit.[br]Bibliography11 September 1876, British patent no. 3,552 (Jablochkoff's candle).22 May 1877, British patent no. 1,996 (transformer or induction coil distribution).Further ReadingW.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 30, pp. 393–407 (a detailed account). W.E.Langdon, 1877, "On a new form of electric light", Journal of the Society ofTelegraph Engineers 6:303–19 (an early report on Jablochkoffs system).Engineering (1878) 26:125–7.GW
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