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, a very ingenious mechanic of London, who introduced several improvements in the mechanism of time-keepers, for which he received premiums from the Board of Longitude. He was the inventor of the expansion balance, and of the present detached escapement, and the first artist who ever applied the gold cylindrical spring to the balance of a time-piece. He died in the fifty-fifth year of his age, at Well-hall, near Eltham in Kent, August 25, 1799. The following publications may be consulted for an account of his improvements: “An account kept during thirteen months in the Royal Observatory at Greenwich, of the going of a Pocket Chronometer, made on a new construction by John Arnold, having his new-invented balance spring, and a compensation for the effects of heat and cold in the balance. Published by permission of the Board of Longitude,” 4to, 1780. lf A Letter from Mr. Christian Meyer, astronomer to the elector Palatine, to Mr. N. N. on the going of a new Pendulum Clock, made by Mr. John Arnold, and set up in the elector’s observatory at Manheim, translated from the German,“4to, 1781.” On the Longitude; in a letter to the Commissioners of that Board; containing remarks on the accounts given of a Clock at Manheim, and tlaat of a Pocket Chronometer at Greenwich; both made by Mr. John Arnold,“4to, 1781.” An Answer from John Arnold to an anonymous letter on the Longitude, 4to, 1782.