Harrison, JOHN

Harrison, JOHN, the inventor of the chronometer for determining longitude at sea, was born at Foulby, near Pontefract, Yorkshire, in 1693. His mechanical genius, which showed itself at an early age, led him to study the construction of clocks and watches, with a view to diminish as much as possible their errors and irregularities, and by 1726 he had constructed a timekeeper provided with compensating apparatus for correcting errors due to variations of climate. In 1714 the government had offered prizes of £10,000, £15,000, and £20,000 for the discovery of a method for determining the longitude within 60, 40, and 30 miles respectively. After a long period of persevering labour Harrison made a chronometer which, in a voyage to Jamaica in 1761-62, was found to determine the longitude within 18 miles. After another voyage to Jamaica, and further trials, he was awarded the prize of £20,000 in 1765 and 1767. The success of Harrison's chronometer is owing to the application of the compensation curb to the balance wheel; and on the same principle he invented the gridiron pendulum for clocks. Besides these, he invented the going fusee and the remontoir escapement (see HOROLOGY). Harrison died in London, 24th March 1776. He wrote Description of such Mechanism as will afford a Nice or True Measurement of Times. See The Principles of Mr Harrison's Timekeeper (1767).