GREGORY, the name of a Scottish family, of which many members have attained the highest eminence in various departments of science. The first who thus distinguished himself was David Gregory, son of the minister of Drumoak in Aberdeenshire, and elder brother of the inventor of the reflecting telescope. He is said to have been the first person in Scotland who possessed a barometer; and his curious experiments with this instrument led his ignorant and superstitious neighbours to suspect him of being in league with the devil. He was accordingly tried for witchcraft, but pardoned, as it was proved that he had never exerted his powers except for the good of the sick and poor in his vicinity. His son David, more famous than himself, was born in Aberdeen in 1661, and was educated partly in his native city and partly in Edinburgh. At the early age of twenty-three he became professor of mathematics in the university of the latter town, and was the first who openly taught the Newtonian philosophy in Scotland. In 1691 he was appointed Savilian professor of astronomy at Oxford,1 and held that situation till his death in 1708.
David Gregory's principal works are his Exercitatio Geometrica de dimensione figurarum, Edinb., 1684; Catoptrica et Dioptrica Sphaerica Elementa, Oxon., 1695; Astronomia Physica et Geometrica Elementa, Oxon., 1702. This last is his greatest work, and was highly esteemed by Newton himself, of whose system it is an illustration and a defence. Besides these works we owe to Gregory an excellent edition of Euclid in Greek and Latin; and at the time of his death he was engaged, conjointly with his colleague Halley, in editing the Conics of Apollonius. A treatise of Gregory's on Practical Geometry, which he left in manuscript, was published in 1745 by the celebrated MacLaurin.
Of Gregory's four sons, the eldest, David, became regius professor of modern history at Oxford. He died in 1767, after having been for many years dean of Christ Church College in that university.