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TROUGHTON, EDWARD (1753–1835), scientific instrument maker, was born in the parish of Corney, Cumberland, in October 1753. His family sprang from Lancaster, and many of them were freemen of that town. Edward (who was enrolled a freeman in 1779) was the third son of Francis Troughton, described as a ‘husbandman,’ and was destined for the same way of life. His eldest brother, John Troughton, had, however, set up as a mechanician in London, and on the death, in 1770, of the second brother, Joseph, Edward replaced him as John's apprentice. At the expiry of his term he was admitted to partnership, and the firm started independently as successors to the well-known mechanicians Wright & Cole. After the death of John Troughton a couple of years later, Edward carried on the business alone until 1826, when he took William Simms (1793–1860) into partnership. During a visit to Paris in 1825 he received much attention from men of science, and the king of Denmark sent him a gold medal in 1830. An original member of the Royal Astronomical Society, he regularly attended, undeterred by his deafness, the meetings of its council. He was elected a fellow of the Royal Societies of London and Edinburgh in 1810 and 1822 respectively.

Absorbed in his art, Troughton led a simple and frugal life, desirous rather of fame than of profit. Liberal in professional communications, he showed feelings of rivalry only towards Jesse Ramsden [q. v.] In manner he was blunt and outspoken; in person slovenly. Towards the last he was seldom absent from his dingy back parlour at 136 Fleet Street, where he sat with a huge ear-trumpet at hand, wearing clothes stained with snuff and a soiled wig. He died on 12 June 1835, and was buried in Kensal Green cemetery.

Although precluded from optical work by the family defect of colour blindness, Troughton's inventions and amendments covered a very wide field. The most important of them was a new mode of graduating arcs of circles—‘the greatest improvement,’ according to Sir George Airy, ‘ever made in the art of instrument-making’ (Report Brit. Association, i. 132). He devised it in 1778; ‘but as my brother,’ he wrote, ‘could not readily be persuaded to relinquish to me a branch of the business in which he himself excelled, it was not until 1785 that I produced my first specimen by dividing an astronomical quadrant of two feet radius.’ He received the Copley medal for his description of the method before the Royal Society on 2 Feb. 1809 (Phil. Trans. xcix. 105).

The first modern transit-circle was constructed by Troughton in 1806 for Stephen Groombridge [q. v.] But he disliked the type, and broke to pieces another example of it, after it had cost him 150l., saying, ‘I was afraid I might become covetous as I grew old, and so be tempted to finish it.’ So he contrived instead the mural circle, with which, by a valuable innovation, polar distances were measured directly from the pole. One of those circles, six feet in diameter, erected by him at Greenwich in 1812, continued in use until 1851, and is preserved in the transit room. Instruments of the same kind were sent by him to the observatories of Paris, the Cape, St. Helena, Madras, Cracow, Cadiz, Brussels, Edinburgh, Armagh, and Cambridge. His large transits were of great beauty and finish. The most notable were those procured for Greenwich in 1816, and by Sir James South [q. v.] in 1820. The Greenwich twenty-five foot zenith telescope was also by him. Towards the end of his life, however, the practical execution of his designs devolved mainly upon Simms. The best known of his altazimuth circles belonged to Count Brühl [see Brühl, John Maurice, Count of,] John Pond [q. v.], Sir Thomas Brisbane, John Lee (1783–1866) [q. v.], and Dr. William Pearson. He mounted small telescopes equatorially for the observatories of Coimbra (in 1788), of Armagh and Brussels; but his failure with South's twelve-inch proved disastrous to the peace of his later years.

Troughton made the ‘beam compass’ and hydrostatic balance,’ with which Sir George Shuckburgh [see Shuckburgh-Evelyn, Sir George Augustus William] experimented on weights and measures in 1798 (Phil. Trans. lxxxviii. 137). He also constructed the apparatus used by Francis Baily [q. v.] in restoring the standard yard. His theodolites were of remarkable perfection, and he supplied the instrumental outfit for the American coast survey (1815), the Irish and Indian arc-measurements (1822 and 1829), and other famous geodetical operations. He took particular pains to meet the requirements of seamen. ‘Your fancies can wait,’ he would say to importunate customers, ‘their necessities cannot.’ His sextants were long in almost exclusive use, and he invented in 1788 the ‘double-framed sextant.’ He also devised the dipsector, and (in 1796) the ‘British reflecting circle;’ besides materially improving the marine and mountain barometers, the compensated mercurial pendulum, the ‘marine top,’ ‘snuff-box sextant,’ portable universal dial, and pyrometer. The substitution of spider lines for wires in filar micrometers was due to him.

Troughton read a paper on the repeating circle before the Astronomical Society on 12 Jan. 1821 (Memoirs, i. 33), and contributed to Brewster's ‘Edinburgh Cyclopædia’ articles on the ‘Circle,’ ‘Graduation,’ and other subjects. He wrote besides, in his curt clear style, most of the descriptions of his instruments inserted in astronomical publications. Pearson dedicated to him the second volume of his ‘Practical Astronomy’ (1829). Troughton was unmarried, and his freehold of Welcome Nook in his native parish was inherited by his sister, Mrs. Suddard, and is possessed by her descendants. In the cottage garden there, and in the graveyard of Corney, stand sundials said to have been made by him. A marble bust of him by Sir Francis Chantry, subscribed for by his friends, was placed at his desire in the Royal Observatory, Greenwich.

[Monthly Notices Roy. Astr. Soc. iii. 149 (Sheepshanks); a list of references to the published descriptions of Troughton's instruments is given at p. 154; Lonsdale's Worthies of Cumberland, vi. 113; Grant's Hist. of Astronomy, p. 491; Annual Biogr. and Obit. xx. 471; Ann. Reg. 1835, p. 223; Poggendorff's Biogr.-Lit. Handwörterbuch; information from Mr. J. S. Slinger.]

A. M. C.