Encyclopædia Britannica, Ninth Edition/Troughton, Edward

TROUGHTON, Edward (1753-1835), instrument maker, was born in the parish of Corney in Cumberland in October 1753. He joined his elder brother John in carrying on the business of mathematical instrument makers in Fleet Street, London, and continued it alone after his brother's death, until he in 1826 took W. Simms as a partner. He died in London on 12th June 1835.

Troughton was very successful in improving the mechanical part of most nautical, geodetic, and astronomical instruments. He was completely colour-blind, which prevented him from attempting experiments in optics. The first modern transit circle (see Roemer) was constructed by him in 1806 for Groombridge; but Troughton was dissatisfied with this form of instrument, which a few years afterwards was brought to great perfection by Reichenbach and Repsold (qq.v.), and designed the mural circle in its place. The first instrument of this kind was erected at Greenwich in 1812, and ten or twelve others were subsequently constructed for other observatories; but they were ultimately superseded by Troughton's earlier design, the transit circle, by which the two coordinates of an object can be determined simultaneously. He also made transit instruments, equatorials, &c.; but his failure to construct an equatorial mounting of large dimensions, and the consequent lawsuit with Sir James South, embittered the last years of his life.