Graham, George

SUBJECT AREA: Horology
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b. c.1674 Cumberland, England
d. 16 November 1751 London, England
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English watch-and clockmaker who invented the cylinder escapement for watches, the first successful dead-beat escapement for clocks and the mercury compensation pendulum.
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Graham's father died soon after his birth, so he was raised by his brother. In 1688 he was apprenticed to the London clockmaker Henry Aske, and in 1695 he gained his freedom. He was employed as a journeyman by Tompion in 1696 and later married his niece. In 1711 he formed a partnership with Tompion and effectively ran the business in Tompion's declining years; he took over the business after Tompion died in 1713. In addition to his horological interests he also made scientific instruments, specializing in those for astronomical use. As a person, he was well respected and appears to have lived up to the epithet "Honest George Graham". He befriended John Harrison when he first went to London and lent him money to further his researches at a time when they might have conflicted with his own interests.
The two common forms of escapement in use in Graham's time, the anchor escapement for clocks and the verge escapement for watches, shared the same weakness: they interfered severely with the free oscillation of the pendulum and the balance, and thus adversely affected the timekeeping. Tompion's two frictional rest escapements, the dead-beat for clocks and the horizontal for watches, had provided a partial solution by eliminating recoil (the momentary reversal of the motion of the timepiece), but they had not been successful in practice. Around 1720 Graham produced his own much improved version of the dead-beat escapement which became a standard feature of regulator clocks, at least in Britain, until its supremacy was challenged at the end of the nineteenth century by the superior accuracy of the Riefler clock. Another feature of the regulator clock owed to Graham was the mercury compensation pendulum, which he invented in 1722 and published four years later. The bob of this pendulum contained mercury, the surface of which rose or fell with changes in temperature, compensating for the concomitant variation in the length of the pendulum rod. Graham devised his mercury pendulum after he had failed to achieve compensation by means of the difference in expansion between various metals. He then turned his attention to improving Tompion's horizontal escapement, and by 1725 the cylinder escapement existed in what was virtually its final form. From the following year he fitted this escapement to all his watches, and it was also used extensively by London makers for their precision watches. It proved to be somewhat lacking in durability, but this problem was overcome later in the century by using a ruby cylinder, notably by Abraham Louis Breguet. It was revived, in a cheaper form, by the Swiss and the French in the nineteenth century and was produced in vast quantities.
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Principal Honours and Distinctions
FRS 1720. Master of the Clockmakers' Company 1722.
Bibliography
Graham contributed many papers to the Philosophical Transactions of the Royal Society, in particular "A contrivance to avoid the irregularities in a clock's motion occasion'd by the action of heat and cold upon the rod of the pendulum" (1726) 34:40–4.
Further Reading
Britten's Watch \& Clock Maker's Handbook Dictionary and Guide, 1978, rev. Richard Good, 16th edn, London, pp. 81, 84, 232 (for a technical description of the dead-beat and cylinder escapements and the mercury compensation pendulum).
A.J.Turner, 1972, "The introduction of the dead-beat escapement: a new document", Antiquarian Horology 8:71.
E.A.Battison, 1972, biography, Biographical Dictionary of Science, ed. C.C.Gillespie, Vol. V, New York, 490–2 (contains a résumé of Graham's non-horological activities).
DV

Biographical history of technology. - Taylor & Francis e-Librar. . 2005.

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