GREGORY (David), nephew of the preceding, was born June 24th, 1661, at the same place, where he also received the first grounds of his learning; but was afterwards removed to Edinburgh, and took the degree of master of arts in that university. The great advantage of his uncle's papers induced his friends to recommend the mathematics to him; and he had a natural subtlety of genius, which particularly fitted him for that study, to which he applied with indefatigable industry; and succeeded so well, that he was advanced to the mathematical chair at Edinburgh, at the age of 25; and the same year he published a treatise entitled, Exercitatio geometrica de dimensione figurarum, Edinb. 1684, 4to.
He had already seen some hints in his uncle's papers concerning Sir Isaac Newton's method, of which he made the best use he could, and the advantage he found thereby raised an ardent desire in him to see that method published. Under this impatient expectation, the Principia was no sooner out in 1687, but our author took it in hand, and presently made himself so much master of it as to be able to read his professorial lectures upon the philosophy contained in it; and causing his scholars to perform their exercises for their degrees upon several branches of it, became its first introducer into the schools.
He continued at Edinburgh till the year 1691; when hearing the news of Dr Bernard's intention to resign the Savilian professorship at Oxford, he left Scotland, and, coming to London, was admitted a member of the Royal Society. Proceeding to Oxford, he was elected astronomical professor there, having been first admitted of Balliol-college, incorporated master of arts, and created doctor of physic. He had no relish for the technical part of his profession, and was seldom seen in the observatory. His genius lay more to geometry, in which he distinguished himself both by his Elements of Optics, and of Physical and geometrical astronomy. This last is reckoned his masterpiece; and having finished it in 1702, he immediately engaged in carrying on the noble design of his predecessor, Dr Bernard, to print all the works of the ancient mathematicians; the first fruits of which appeared in an
edition of Euclid's works in Greek and Latin, in folio, the following year; and, in the same design, he afterwards joined with his colleague Dr Halley, in preparing an edition of Apollonius's Conics. Dr Bernard had the materials for the first four books, which our author undertook to complete, but was prevented by his death, which happened Oct. 16. 1710.