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1 Phillips, Edouard
SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering[br]b. 21 May 1821 Paris, Franced. 14 December 1889 Pouligny-Saint-Martin, France[br]French engineer and mathematician who achieved isochronous oscillations of a balance by deriving the correct shape for the balance spring.[br]Phillips was educated in Paris, at the Ecole Polytechnic and the Ecole des Mines. In 1849 he was awarded a doctorate in mathematical sciences by the University of Paris. He had a varied career in industry, academic and government institutions, rising to be Inspector- General of Mines in 1882.It was well known that the balance of a watch or chronometer fitted with a simple spiral or helical spring was not isochronous, i.e. the period of the oscillation was not entirely independent of the amplitude. Watch-and chronometer-makers, notably Breguet and Arnold, had devised empirical solutions to the problem by altering the curvature of the end of the balance spring. In 1858 Phillips was encouraged to tackle the problem mathematically, and two years later he published a complete solution for the helical balance spring and a partial solution for the more complex spiral spring. Eleven years later he was able to achieve a complete solution for the spiral spring by altering the curvature of both ends of the spring. Phillips published a series of typical curves that the watch-or chronometer-maker could use to shape the ends of the balance spring.[br]Principal Honours and DistinctionsAcadémie des Sciences 1868. Chairman, Jury on Mechanics, Universal Exhibition 1889.Bibliography1861, "Mémoire sur l'application de la Théorie du Spiral Réglant", Annales des Mines 20:1–107.1878, Comptes Rendus 86:26–31.An English translation (by J.D.Weaver) of both the above papers was published by the Antiquarian Horological Society in 1978 (Monograph No. 15).Further ReadingJ.D.Weaver, 1989, "Edouard Phillips: a centenary appreciation", Horological Journal 132: 205–6 (a good short account).F.J.Britten, 1978, Britten's Watch and Clock Maker's Handbook, 16th edn, rev. R Good (a description of the practical applications of the balance spring).DV -
2 Branly, Edouard Eugène
[br]b. 23 October 1844 Amiens, Franced. 24 March 1940 Paris, France[br]French electrical engineer, who c.1890 invented the coherer for detecting radio waves.[br]Branly received his education at the Lycée de Saint Quentin in the Département de l'Aisne and at the Henri IV College of Paris University, where he became a Fellow of the University, graduating as a Doctor of Physics in 1873. That year he was appointed a professor at the College of Bourges and Director of Physics Instruction at the Sorbonne. Three years later he moved to the Free School in Paris as Professor of Advanced Studies. In addition to these responsibilities, he qualified as an MD in 1882 and practised medicine from 1896 to 1916. Whilst carrying out experiments with Hertzian (radio) waves in 1890, Branly discovered that a tube of iron filings connected to a source of direct voltage only became conductive when the radio waves were present. This early form of rectifier, which he called a coherer and which needed regular tapping to maintain its response, was used to operate a relay when the waves were turned on and off by Morse signals, thus providing the first practical radio communication.[br]Principal Honours and DistinctionsPapal Order of Commander of St George 1899. Légion d'honneur, Chevalier 1900, Commandeur 1925. Osiris Prize (jointly with Marie Curie) 1903. Argenteuil Prize and Associate of the Royal Belgian Academy 1910. Member of the Academy of Science 1911. State Funeral at Notre Dame Cathedral.BibliographyAmongst his publications in Comptes rendus were "Conductivity of mediocre conductors", "Conductivity of gases", "Telegraphic conduction without wires" and "Conductivity of imperfect conductors realised at a distance by wireless by spark discharge of a capacitor".Further ReadingE.Hawkes, 1927, Pioneers of Wireless, London: Methuen. E.Larien, 1971, A History of Invention, London: Victor Gollancz.V.J.Phillips: 1980, Early Radio Wave Detectors, London: Peter Peregrinus.KF -
3 Arnold, John
SUBJECT AREA: Horology[br]b. 1735/6 Bodmin (?), Cornwall, Englandd. 25 August 1799 Eltham, London, England[br]English clock, watch, and chronometer maker who invented the isochronous helical balance spring and an improved form of detached detent escapement.[br]John Arnold was apprenticed to his father, a watchmaker, and then worked as an itinerant journeyman in the Low Countries and, later, in England. He settled in London in 1762 and rapidly established his reputation at Court by presenting George III with a miniature repeating watch mounted in a ring. He later abandoned the security of the Court for a more precarious living developing his chronometers, with some financial assistance from the Board of Longitude. Symbolically, in 1771 he moved from the vicinity of the Court at St James's to John Adam Street, which was close to the premises of the Royal Society for the Encouragement of Arts, Manufactures \& Commerce.By the time Arnold became interested in chronometry, Harrison had already demonstrated that longitude could be determined by means of a timekeeper, and the need was for a simpler instrument that could be sold at an affordable price for universal use at sea. Le Roy had shown that it was possible to dispense with a remontoire by using a detached escapement with an isochronous balance; Arnold was obviously thinking along the same lines, although he may not have been aware of Le Roy's work. By 1772 Arnold had developed his detached escapement, a pivoted detent which was quite different from that used on the European continent, and three years later he took out a patent for a compensation balance and a helical balance spring (Arnold used the spring in torsion and not in tension as Harrison had done). His compensation balance was similar in principle to that described by Le Roy and used riveted bimetallic strips to alter the radius of gyration of the balance by moving small weights radially. Although the helical balance spring was not completely isochronous it was a great improvement on the spiral spring, and in a later patent (1782) he showed how it could be made more truly isochronous by shaping the ends. In this form it was used universally in marine chronometers.Although Arnold's chronometers performed well, their long-term stability was less satisfactory because of the deterioration of the oil on the pivot of the detent. In his patent of 1782 he eliminated this defect by replacing the pivot with a spring, producing the spring detent escapement. This was also done independendy at about the same time by Berthoud and Earnshaw, although Earnshaw claimed vehemently that Arnold had plagiarized his work. Ironically it was Earnshaw's design that was finally adopted, although he had merely replaced Arnold's pivoted detent with a spring, while Arnold had completely redesigned the escapement. Earnshaw also improved the compensation balance by fusing the steel to the brass to form the bimetallic element, and it was in this form that it began to be used universally for chronometers and high-grade watches.As a result of the efforts of Arnold and Earnshaw, the marine chronometer emerged in what was essentially its final form by the end of the eighteenth century. The standardization of the design in England enabled it to be produced economically; whereas Larcum Kendall was paid £500 to copy Harrison's fourth timekeeper, Arnold was able to sell his chronometers for less than one-fifth of that amount. This combination of price and quality led to Britain's domination of the chronometer market during the nineteenth century.[br]Bibliography30 December 1775, "Timekeepers", British patent no. 1,113.2 May 1782, "A new escapement, and also a balance to compensate the effects arising from heat and cold in pocket chronometers, and for incurving the ends of the helical spring…", British patent no. 1,382.Further ReadingR.T.Gould, 1923, The Marine Chronometer: Its History and Development, London; reprinted 1960, Holland Press (provides an overview).V.Mercer, 1972, John Arnold \& Son Chronometer Makers 1726–1843, London.See also: Phillips, EdouardDV -
4 Mechanical, pneumatic and hydraulic engineering
See also: INDEX BY SUBJECT AREA[br]Clement, JosephDu ShiDu YuGongshu PanLi BingMa JunMurdock, WilliamSomerset, EdwardBiographical history of technology > Mechanical, pneumatic and hydraulic engineering
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