(Colin), a most eminent mathematician and philosopher, the son of a clergyman, and born at Kilmoodan in Scotland in 1698. He was sent to the university of Glasgow in 1709, and took the degree of master of arts in his 15th year; on which occasion he composed and defended a thesis on the power of gravity with great applause. In 1717, he obtained the professorship of mathematics in the Marischal college of Aberdeen against a very able competitor; and, going afterwards to London, contracted an acquaintance with Sir Isaac Newton, Dr. Hoadley, Dr. Clarke, Martin Folkes, esq. with other eminent men; and was admitted a member of the Royal Society. In 1722 he travelled as tutor to the eldest son of lord Polwarth; and at Lorrain wrote his piece On the percussion of bodies, which gained the prize of the Royal Academy of Sciences in 1724; but, on the death of his pupil at Montpelier, he returned immediately to Aberdeen. He was hardly settled there, when he was chosen to supply the place of Mr. James Gregory, as professor at Edinburgh, where his mathematical scholars soon became very numerous. In 1745, having been very active in fortifying the city of Edinburgh against the rebel army, he was obliged to fly into the north of England; in which expedition he laid the foundation of an illness that put an end to his life in 1746. He published A complete system of flexions, 2 vols. fol.; several curious papers in the Philosophical Transactions, and in the Edinburgh Medical Essays; and after his death appeared his Algebra, and Account of Sir Isaac Newton's philosophical discoveries. His peculiar merit as a philosopher was, that all his studies were directed to general utility, and promoting mechanical arts.