Dictionary of National Biography, 1885-1900/Sharp, Abraham

by Henry Frederick Baker

SHARP, ABRAHAM (1651–1742), mathematician, younger son of John Sharp of Little Horton, by Mary, daughter of Robert Clarkson of Bradford (married 12 Dec. 1632), was born in 1651 at Little Horton, near Bradford, and baptised 1 June 1653 (pedigree in Thoresby's Leeds, 1816, p. 37). After attending Bradford grammar school he was apprenticed to William Shaw, mercer of York, and then to a merchant at Manchester, but he gave up his business and moved to Liverpool, where he taught and devoted himself to mathematics. Here he met John Flamsteed [q. v.], by whom he was recommended to a post in Chatham dockyard. From about 1684 he seems to have been employed by Flamsteed in the newly founded Greenwich observatory. In 1688 he was employed to make a mural arc, the first of Flamsteed's instruments that proved satisfactory (cf. Baily, Flamsteed, 1835, p. 55; Flamsteed's Prolegomena to vol. iii. of the Historia Celestis, 1725, p. 108). The mural was finished in fourteen months, costing Flamsteed 120l.; it was 79 inches in radius, and contained 140 degrees on the limb. Sharp left the observatory in August 1690, so that he might teach mathematics in London (cf. Flamsteed MSS. vol. iv. 4 Nov. 1690). Early in 1691, however, he removed to Portsmouth to take ‘a clerk's place in the king's shipyard.’ He retired in 1694 to Little Horton, calculating and making astronomical instruments and models, and in correspondence with scientific men (cf. Gent. Mag. 1781, p. 461). In a report on astronomical instruments (Phil. Trans. lxxvi. 1786) John Smeaton says: ‘I look upon Mr. Sharp as having been the first person that cut accurate and delicate divisions upon astronomical instruments.’ He calculated π to 72 places of decimals (Hutton, Diction.) His book, ‘Geometry Improved (1) by a Table of Segments of Circles, (2) a Concise Treatise of Polyedra, by A. S. Philomath,’ London, 1717, is remarkable for the great number of its calculations, among other things the logarithms of the numbers from 1 to 100, and of all the primes up to 1100, each calculated to 61 figures of decimals; and for the plates of solid figures cut by his own hand, which are very clear. From his correspondence, beginning 6 Feb. 1701 (noticed in Baily's Flamsteed) it appears that he continued to help Flamsteed. It was to Sharp and Crosthwait that the world was indebted for the final publication of the ‘British Catalogue’ (l. c. p. 410). On 31 Aug. 1714 Flamsteed wrote to Sharp: ‘I would desire you to calculate the eclipses of the [Jupiter's] satellites for the next year.’ On 11 Oct. 1715 Flamsteed wrote him: ‘Yours brought the eclipses of ♃ satellites for the next year, 1716. I thank you heartily for them.’ After Flamsteed's death (4 June 1720), Crosthwait wrote to Sharp: ‘Yours of the 20th May brought the most acceptable news of your kind offer to lay down the stars and draw the lines and divisions of all the maps of the constellations of the zodiac. When the world shall know that these were done by the hands of Mr. Sharp, it will make Mr. Flamsteed's works more valuable as well as more useful.’ Others of Flamsteed's letters to Sharp are full of his complaints of Newton's double dealing. Sharp died near Bradford, Yorkshire, on 18 July 1742, aged 91 (Gent. Mag. 1742, p. 387).

[Authorities cited; Cudworth's Life and Correspondence of Abraham Sharp, 1889; Notes and Queries, 8th ser. xii. 344.]

H. F. B.

Dictionary of National Biography, Errata (1904), p.247
N.B.— f.e. stands for from end and l.l. for last line

Page	Col.	Line
400	ii	6	Sharp, Abraham: after Bradford insert and baptised in June 1653
		7	for He was apprenticed read After attending Bradford Grammar School he was apprenticed to William Shaw, mercer, of York, and then
		13	for From 1676 read From about 1684
		27	after 1690). insert Early in 1691, however, he removed to Portsmouth to take a clerk's place in the king's shipyard.'
401	i	11	for 15 July read 18 July
		13	after cited insert cf. Cudworth's Life and Correspondence of Abraham Sharp, 1889