already attempted by Fermat before 1629 (Œuvres de Fermat, 1891, i. 3–51, ii. 105), and by Francis Schooten in 1657 (Exercitationes Mathemat.) Simson published his conclusions in 1749 in a work entitled ‘Apollonii Pergæi Locorum Planorum libri II, restituti a R. Simson’ (Glasgow, 4to), which was translated into German in 1822 by W. A. Diesterweg (Mayence, 8vo).
Simson next occupied himself with the restoration of the ‘Sectio Determinata’ of Apollonius, which had already been imperfectly accomplished by Alexander Anderson [q. v.] in 1612, and by Willebrodus Snellius in 1634 (Pierre Herigone, Cursus Mathematicus, tome i.). The results of his labours were published among his posthumous works. Simson's researches among the mathematical fragments of classical antiquity, although his restorations were far from complete, and in many cases were more or less conjectural, notably elucidated the obscurities of ancient geometry.
In 1746 the university of St. Andrews conferred on him the honorary degree of M.D., and in 1756 he issued an edition of the ‘Elements of Euclid’ (Glasgow, 4to; 24th ed. 1834), to which he added the ‘Data’ in 1762. His edition has always held a high character for precision and accuracy, and has formed the basis of most modern textbooks, but in some instances his reverence for antiquity has asserted itself at the expense of his critical discernment. Refusing to admit any imperfection in Euclid, he imputed all shortcomings to his editors and copyists.
In 1761 he retired from the active duties of his chair, and employed his leisure chiefly in correcting his mathematical works. He died at Glasgow, unmarried, on 1 Oct. 1768, and was buried in the Blackfriars burial-ground.
A posthumous edition of Simson's unpublished works was issued at Glasgow in 1776, under the superintendence of James Clow, professor of philosophy at Glasgow, and at the expense of Philip Stanhope, second earl Stanhope. Besides the treatises mentioned, it contained two short tracts entitled ‘De Logarithmis liber’ and ‘De Limitibus Quantitatum et Rationum, Fragmentum,’ which have since been reprinted by Francis Maseres [q. v.] in his ‘Scriptores Logarithmici.’ A treatise on the ‘Elements of Plane Trignometry’ was published with the later editions of Simson's ‘Elements of Euclid,’ and also separately at Dublin in 1841. His library and all his manuscripts, including an incomplete edition of Pappus, and eighteen volumes on mathematical subjects, entitled ‘Adversaria,’ were presented to the university library at Glasgow.
Simson's portrait hangs in the college hall at Glasgow, and an engraving from it is prefixed to Trail's account of his life and writings.
[Trail's Account of the Life and Writings of Robert Simson, 1812; Encycl. Britannica, 8th ed. xx. 298–302, 9th ed. xxii. 88; English Cycl. Biography, v. 519; Anderson's Scottish Nation, iii. 455; Chambers's Eminent Scotsmen, iii. 350; Chalmers's Biogr. Dict. 1816, xxviii. 21; Hutton's Philosophical and Mathematical Dictionary, 1815; Bromley's Catalogue of Portraits, p. 394; Notes and Queries, I. i. 133, III. ii. 480, 499; New Statistical Account of Scotland, v. 252; Ball's Short History of Mathematics, p. 55.]
SIMSON, THOMAS (1696–1764), professor of medicine at St. Andrews, born in 1696 at Kirktonhall in the parish of West Kilbride, Ayrshire, was third son of John Simson of Kirktonhall, by his wife Agnes, daughter of Patrick Simson, minister of Renfrew. Robert Simson [q. v.], the mathematical professor, was his brother. In 1721 James Brydges, duke of Chandos, established a medical professorship in the university of St. Andrews, and on 10 Jan. 1722 Simson was admitted as its first incumbent. He held the chair until his death. In 1744 he was elected an honorary fellow of the Royal College of Physicians at Edinburgh (Charter and Regulations of the Royal College of Physicians, p. 95). He died on 30 April 1764 at St. Andrews.
About 1724 he married a daughter of Sir John Preston of Prestonhall, Fife, who was deprived of his estates in 1715. By her he had four sons and two daughters; of the former, James was professor of medicine at St. Andrews in succession to his father from 1764 to 1770. He was the author of: 1. ‘De re Medica,’ Edinburgh, 1726, 8vo. 2. ‘De Erroribus circa Materiam Medicam,’ 1726, 8vo. 3. ‘System of the Womb,’ London, 1729, 8vo. 4. ‘Enquiry on the Vital and Animal Actions,’ 1752, 8vo.
[Scots Mag. 1764, p. 167; Paterson's Hist. of Ayr and Wigtown, III. ii. 367; Burke's Commoners, iii. 102.]
SIMSON, WILLIAM (1800–1847), Scottish painter, second son of Alexander Simson, merchant, was born at Dundee in 1800. His father was admitted a burgess of Dundee in 1792, and, though engaged in commerce, was deeply interested in art. Three of his sons became artists: George (1791–1862), a portrait- and landscape-painter, who became a member of the Royal Scottish Aca-
