# David Gregory (1659-1708)

David Gregory, the astronomer and mathematician, was born at Kinnairdie in Banffshire, north east Scotland on either 6 March 1659 or 24 June 1661 (sources differ). From Marischal College, Aberdeen, he entered the University of Edinburgh, graduating M.A. on 28 November 1683. A month prior to his graduation he was elected to the Chair of Mathematics, at one time occupied by his uncle, the mathematician James Gregory (1638-1675).

In 1684, David Gregory published in Edinburgh his *Exercitatio geometrica de dimensione figurarum * in which, with the assistance of his uncle's work, he extended the method of quadratures by infinite series. As a professor, Gregory was the first to lecture publically on the Newtonian philosophy. His lecture notes show that they covered a broad range of subjects including geodesy, optics, dynamics, and various branches of mathematics. In 1691 he went to London where he was introduced to Newton and recommended to John Flamsteed (1646-1719), the first astronomer royal. With the combined influence of Newton and Flamsteed, Gregory was awarded the Savilian Chair of Astronomy at Oxford in 1691.

In 1692 he took the degrees of M.A. and M.D. at Oxford, and he became a master commoner of Balliol College. Also in 1692, he was elected a fellow of the Royal Society. In 1699 he was appointed as mathematical tutor to William, Duke of Gloucester. The substance of his work delivered in Edinburgh, and published there in 1684, was contained in his *Catoptricae et dioptricae sphaericae elementa * (1695) and was adapted to undergraduates. In this work, Gregory gave the first hint of the achromatic telescope when he referred to the possibility of counteracting colour aberration in lenses by combining in them media of different densities. The work was reprinted in Edinburgh in 1713 and translated into English (from Latin) in 1715.

His principle work however was *Astronomiae physicae et geometricae elementa * (1702). This was the first text-book on gravitational principles and it remodelled astronomy in conformity with physical theory. His next work, in Greek and Latin, was *Euclides * (1703) which was an edition of all the writings attributed to Euclid.

In 1704, Gregory was nominated to the committee charged by Prince George with the inspection and printing of the Greenwich observations, and in 1705 he was chosen as honorary fellow of the Royal College of Physicians of Edinburgh. Gregory died on 10 October 1708 at the Greyhound Inn at Maidenhead, Berkshire, while on his return to London from Bath after taking the cure there for consumption.