# Dictionary of National Biography, 1885-1900/Sinclair, George (d.1696)

​SINCLAIR or SINCLAR, GEORGE (d. 1696), professor successively of philosophy and mathematics at Glasgow, was probably a native of East Lothian. On the title-page of his ‘Ars Nova’ he styles himself ‘Scoto-Lothiani,’ and he possessed property in the town of Haddington (Laing, Charters). His brother, John Sinclar, was for a time regent in St. Leonard's College in St. Andrews, and in 1647 he became minister of Ormiston in East Lothian, whence in 1682 he went to Holland, and died at Delft in 1689 (Scott, Fasti Eccl. Scoticanæ, i. 301). In 1654 George was acting as a ‘pedagogue’ in St. Andrews, whence he was brought to Glasgow (Baillie, Letters and Journals, ed. Laing, iii. 285). He was admitted a master of Glasgow University on 18 Oct. 1654, and in the same year was appointed professor of philosophy at Glasgow. He was one of the first in Scotland who devoted attention to the study of physics, then held, as he laments, of little account. In 1655 he was associated with an unnamed experimenter, probably Maule of Melgum, the original inventor of the diving-bell, in using the new invention in exploring the contents of the ship Florida, a relic of the Armada, wrecked on the Isle of Mull (Ars Nova, pp. 220 et seq.). He remained at Glasgow as a professor until June 1666, when he was obliged to resign as he refused to comply with the episcopal form of church government (Wodrow, History, &c., ed. 1829, iii. 3).
On leaving Glasgow, Sinclar came to ​Edinburgh, where at one time he taught mathematics in the college, although he appears to have resided at Leith, and is described as schoolmaster there. He occupied himself in making and recording experiments in physics. He was one of the first in Scotland to utilise the barometer, which he styled the baroscope, as a means of measuring altitudes and also the depth of mines, although he based his calculations on erroneous principles. He appears also to have been employed by coalowners in the Lothians to report on the extent and dip of the various beds of coal in their neighbourhood, and his report was published in 1672 in his ‘Hydrostaticks,’ where he suggested the best methods of draining off water from the coal seams. In this work he shows a knowledge of English collieries as well as of Scottish. The book, perhaps owing to the author's self-complacency, provoked a severe attack by James Gregory [q. v.], professor of mathematics in St. Andrews, under the pseudonym of ‘Patrick Mathers, arch bedal to the university of St. Andrews.’ Sinclar wrote, but never published, a retort, entitled ‘Cacus pulled out of his Den by the Heels’ (manuscript in Glasgow University Library). Gregory's satire was so severe that it injured for a time the sale of Sinclar's book; but in 1673 and 1674 he superintended, at the request of the magistrates, the laying of pipes to bring water into the city of Edinburgh. It was in 1685 that he published the work by which he is best known, ‘Satans Invisible World discovered’ (Edinburgh, 12mo), written to ‘prove the existence of devils, spirits, witches, and apparitions,’ and to vindicate this belief against those who would assault ‘one of the outworks of religion.’ It was dedicated to the Earl of Wintoun. Sinclar supplies many marvellous narratives, which are declared to be authentic. The writer obtained from the privy council the sole right of publication for eleven years. The book has been frequently reprinted.
After the revolution or early in 1689, Sinclar resumed his chair of philosophy in the college of Glasgow, and two years later he demitted that charge on being appointed professor of mathematics (3 March 1691), a post which he held till his death. The last notice of him in the records of the college is on 18 April 1696, and he appears to have died in that year. The college treasurer records that he died poor, but he ‘was ane honest man.’
Sinclar also published: 1. ‘Tyrocinia Mathematica, in iv. Tractatus, viz., Arithmeticum, Sphæricum, Geographicum et Echometricum divisa,’ Glasgow, 1661, 12mo, which was reissued with a new title-page as ‘Principia Mathematica, Editio secunda priore correctior,’ London, 1672, 12mo. 2. ‘Ars Nova et Magna Gravitatis et Levitatis, sive Dialogorum Philosophicorum libri sex de aeris vera et reale gravitate,’ Rotterdam, 1669, 4to. 3. ‘The Hydrostaticks, or the Weight Force and Pressure of Fluid Bodies made evident by Physical and Sensible Experiments,’ Edinburgh, 1672, 4to, containing also a ‘Short History of Coal.’ This work was reissued, with some additions, under the new title of ‘Natural Philosophy improven by New Experiments,’ Edinburgh, 1683, 4to. 4. ‘The Principles of Astronomy and Navigation, or a clear, short, yet full Explanation of all Circles of the Celestial and Terrestrial Globes,’ Edinburgh, 1688, 4to.
Besides these, Sinclar published in 1684, as his own composition, a work styled ‘Truth's Victory over Error,’ with an elaborate preface enumerating his other books. This work was a translation of the Latin lectures on the confession of faith delivered by David Dickson [q. v.], professor of divinity in Glasgow. Sinclar's version reached a second edition in 1688. The first edition to bear Dickson's name was issued at Glasgow in 1726.
J. A-n.