(John), an eminent physician and antiquary, was the eldest son of John Greaves rector of Colemore, near Alresford in Hampshire, and born in 1602. He was educated at Balliol College in Oxford, from which he removed to Merton. He was afterwards, on the foot of his great merit, chosen geometry professor of Gresham college. His ardent thirst of knowledge soon carried him into several parts of Europe, where he eagerly seized every opportunity of improving it. His next voyage was into the eastern countries; where nothing remarkable in the heavens, earth, or even subterraneous places, seems to have escaped his nice observation. He, with indefatigable industry, and even at the peril of his life, collected a considerable number of Arabic, Peric, and Greek, manuscripts, for archbishop Laud. Of these he well knew the value, as he was a master of the languages in which they were written. He also collected for that prelate many oriental gems and coins. He took a more accurate survey of the pyramids than any traveller who went before him. On his return from the East, he visited several parts of Italy a second time. During his stay at Rome, he made a particular inquiry into the true state of the ancient weights and measures. Soon after he had finished his second voyage, he was chosen Savilian professor of astronomy at Oxford. He was eminently qualified for this professorship, as the works of ancient and modern astronomers were familiar to him. His books relating to oriental learning, his Pyramidographia, or a description of the pyramids in Egypt, his Epocha Celebrioris, and other curious and useful pieces, of which Mr Ward has given us a catalogue, show him to have been a great man. Those which he intended to publish would have shown him to be a greater; but he was stopped in his great career by death in 1652.