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Graham, George (1675-1751) (DNB00)


GRAHAM, GEORGE (1675–1751), mechanician, was born at Horsgill in the parish of Kirklinton, Cumberland, in 1675. In 1688 he was apprenticed to a watchmaker in London, and attracted the notice of the well-known Tompion. He was treated with the utmost kindness by Tompion, to whose business he eventually succeeded. Graham endeavoured to construct a pendulum which should not be affected by the weather. After many experiments upon the properties of metals when heated, he invented the exceedingly ingenious mercurial pendulum. It was so constructed that the expansion of a steel pendulum was exactly compensated by the expansion of the mercury in a jar connected with it, and the vibrating length of the whole thus preserved constant. To obviate the inconveniences caused by the fluidity of mercury, he suggested the compensating action of bars of two kinds of metal, but did not work out the problem. He also invented the 'dead-beat escapement,' an improvement upon Clement's 'anchor escapement,' which has ever since held its ground. Graham was the first general mechanician of his day. He was widely acquainted with practical astronomy, invented many valuable astronomical instruments, and improved others. His manual dexterity was remarkable, and his precision of construction and thoroughness of work unrivalled. Graham made for Halley the great mural quadrant at Greenwich observatory, and also the fine transit instrument and the zenith sector used by Bradley in his discoveries. He supplied the French Academy with the apparatus used for the measurement of a degree of the meridian, and constructed the most complete planetarium known at that time, in which the motions of the celestial bodies were demonstrated with great accuracy. This was made in cabinet form, at the desire of the Earl of Orrery. Graham was a member of the Society of Friends. Though his business was most remunerative, he was above mere money-making. He was singularly frank in communicating his discoveries. He kept his cash in a strong box, having a conscientious objection to interest, and at his death he had bank notes which had been in his possession for thirty years. Though never wasteful he lent considerable sums to friends, accepting no interest. He was many years a fellow of the Royal Society, and in the 'Philosophical Transactions' (vols. xxxi-xlii.) are numerous communications from him upon his discoveries. Graham died on 20 Nov. 1751, at his house in Fleet Street, and was buried in Westminster Abbey, in the same grave as Tompion.

[Gent. Mag. 1751, p. 523; Hutchison's Hist. of Cumberland, 1794; Phil. Trans.]

J. B-y.