EARNSHAW, THOMAS

born Feb. 4, 1749, Ashton-under-Lyne, Lancashire, Eng. died March 1, 1829, London English watchmaker, the first to simplify and economize in producing chronometers so as to make them available to the general public. Earnshaw became an apprentice at the age of 14 and later set up a shop in London. He made significant improvements in the transit clock at the Royal Observatory of Greenwich, London, and, independently of John Arnold, also of Great Britain, he developed the bimetallic compensation balance. In developing watch mechanisms, Earnshaw also invented the cylindrical balance spring and the detached (or free) detent escapement.