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1 Harwood, John
SUBJECT AREA: Horology[br]b. 1893 Bolton, Englandd. 9 August 1964[br]English watchmaker, inventor and producer of the first commercial self-winding wrist watch.[br]John Harwood served an apprenticeship as a watch repairer in Bolton, and after service in the First World War he obtained a post with a firm of jewellers in Douglas, Isle of Man. He became interested in the self-winding wrist watch, not because of the convenience of not having to wind it, but because of its potential to keep the mainspring fully wound and to exclude dust and moisture from the watch movement. His experience at the bench had taught him that these were the most common factors to affect adversely the reliability of watches. Completely unaware of previous work in this area, in 1922 he started experimenting and two years later he had produced a serviceable model for which he was granted a patent in 1924. The watch operated on the pedometer principle, the mainspring being wound by a pivoted weight that oscillated in the watch case as a result of the motion of the arm. The hands of his watch were set by rotating the bezel surrounding the dial, dispensing with the usual winding/hand-setting stem which allowed dust and moisture to enter the watch case. He took the watch to Switzerland, but he was unable to persuade the watchmaking firms to produce it until he had secured independent finance to cover the cost of tooling. The Harwood Self-Winding Watch Company Ltd was set up in 1928 to market the watches, but although several thousand were produced the company became a victim of the slump and closed down in 1932. The first practical self-winding watch also operated on the pedometer principle and is attributed to Abraham-Louis Perrellet (1770). The method was refined by Breguet in France and by Recordon, who patented the device in England, but it proved troublesome and went out of fashion. There was a brief revival of interest in self-winding watches towards the end of the nineteenth century, but they never achieved great popularity until after the Second World War, when they used either self-winding mechanisms similar to that devised by Harwood or weights which rotated in the case.[br]Principal Honours and DistinctionsBritish Horological Institute Gold Medal 1957.Bibliography1 September 1924, Swiss patent no. 106,582.Further ReadingA.Chapuis and E.Jaquet, 1956, The History of the Self-Winding Watch, London (provides general information)."How the automatic wrist watch was invented", 1957, Horological Journal 99:612–61 (for specific information).DV -
2 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 -
3 Shortt, William Hamilton
SUBJECT AREA: Horology[br]b. 28 September 1881d. 4 February 1971[br]British railway engineer and amateur horologist who designed the first successful free-pendulum clock.[br]Shortt entered the Engineering Department of the London and South Western Railway as an engineering cadet in 1902, remaining with the company and its successors until he retired in 1946. He became interested in precision horology in 1908, when he designed an instrument for recording the speed of trains; this led to a long and fruitful collaboration with Frank HopeJones, the proprietor of the Synchronome Company. This association culminated in the installation of a free-pendulum clock, with an accuracy of the order of one second per year, at Edinburgh Observatory in 1921. The clock's performance was far better than that of existing clocks, such as the Riefler, and a slightly modified version was produced commercially by the Synchronome Company. These clocks provided the time standard at Greenwich and many other observatories and scientific institutions across the world until they were supplanted by the quartz clock.The period of a pendulum is constant if it swings freely with a constant amplitude in a vacuum. However, this ideal state cannot be achieved in a clock because the pendulum must be impulsed to maintain its amplitude and the swings have to be counted to indicate time. The free-pendulum clock is an attempt to approach this ideal as closely as possible. In 1898 R.J. Rudd used a slave clock, synchronized with a free pendulum, to time the impulses delivered to the free pendulum. This clock was not successful, but it provided the inspiration for Shortt's clock, which operates on the same principle. The Shortt clock used a standard Synchronome electric clock as the slave, and its pendulum was kept in step with the free pendulum by means of the "hit and miss" synchronizer that Shortt had patented in 1921. This allowed the pendulum to swing freely (in a vacuum), apart from the fraction of a second in which it received an impulse each half-minute.[br]Principal Honours and DistinctionsMaster of the Clockmakers' Company 1950. British Horological Society Gold Medal 1931. Clockmakers' Company Tompion Medal 1954. Franklin Institute John Price Wetherill Silver Medal.Bibliography1929, "Some experimental mechanisms, mechanical and otherwise, for the maintenance of vibration of a pendulum", Horological Journal 71:224–5.Further ReadingObituary, 1971, Proceedings of the Institution of Civil Engineers 56:396–7.F.Hope-Jones, 1949, Electrical Timekeeping, 2nd edn, London (a detailed but not entirely impartial account of the development of the free-pendulum clock).See also: Marrison, Warren AlvinDVBiographical history of technology > Shortt, William Hamilton
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4 Hetzel, Max
[br]b. 5 March 1921 Basle, Switzerland[br]Swiss electrical engineer who invented the tuning-fork watch.[br]Hetzel trained as an electrical engineer at the Federal Polytechnic in Zurich and worked for several years in the field of telecommunications before joining the Bulova Watch Company in 1950. At that time several companies were developing watches with electromagnetically maintained balances, but they represented very little advance on the mechanical watch and the mechanical switching mechanism was unreliable. In 1952 Hetzel started work on a much more radical design which was influenced by a transistorized tuning-fork oscillator that he had developed when he was working on telecommunications. Tuning forks, whose vibrations were maintained electromagnetically, had been used by scientists during the nineteenth century to measure small intervals of time, but Niaudet- Breguet appears to have been the first to use a tuning fork to control a clock. In 1866 he described a mechanically operated tuning-fork clock manufactured by the firm of Breguet, but it was not successful, possibly because the fork did not compensate for changes in temperature. The tuning fork only became a precision instrument during the 1920s, when elinvar forks were maintained in vibration by thermionic valve circuits. Their primary purpose was to act as frequency standards, but they might have been developed into precision clocks had not the quartz clock made its appearance very shortly afterwards. Hetzel's design was effectively a miniaturized version of these precision devices, with a transistor replacing the thermionic valve. The fork vibrated at a frequency of 360 cycles per second, and the hands were driven mechanically from the end of one of the tines. A prototype was working by 1954, and the watch went into production in 1960. It was sold under the tradename Accutron, with a guaranteed accuracy of one minute per month: this was a considerable improvement on the performance of the mechanical watch. However, the events of the 1920s were to repeat themselves, and by the end of the decade the Accutron was eclipsed by the introduction of quartz-crystal watches.[br]Principal Honours and DistinctionsNeuchâtel Observatory Centenary Prize 1958. Swiss Society for Chronometry Gold Medal 1988.Bibliography"The history of the “Accutron” tuning fork watch", 1969, Swiss Watch \& Jewellery Journal 94:413–5.Further ReadingR.Good, 1960, "The Accutron", Horological Journal 103:346–53 (for a detailed technical description).J.D.Weaver, 1982, Electrical \& Electronic Clocks \& Watches, London (provides a technical description of the tuning-fork watch in its historical context).DV
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