Contemporary with Sydenham, we find the celebrated Sir Wm. Petty, the founder of the Lansdowne family. He was the eldest son of Anthony Petty, who, Aubrey the Antiquary tells us, was a clothier in Romsey. In his early days he showed great liking for all mechanical operations, and at twelve years of age had acquired considerable skill in carpentry and smiths’ work. Educated at the free school of his native place, at the age of fifteen he began his remarkable career as a self-helping man; from his own account, we learn that he went over to Caen, in Normandy, with a little stock of merchandise, and had such good success that out of the profits he educated himself in the French tongue, and perfected his knowledge of classics and mathematics. In his twentieth year he had saved about three-score pounds, and acquired as much progress in mathematics as any of his age: to his love of learning was joined the desire to acquire wealth; he was at all times _practical_, and seems to have held pecuniary advantage to be the most comprehensive form of the practical. He tells us that when the civil wars between the King and Parliament grew hot “I had _sixty pounds_ in money and went into the Netherlands and France for three years, and vigorously pursued my studies, especially that of medicine at Utrecht, Leyden, Amsterdam, and Paris. I returned to Romsey with about _ten pounds more_ than I had carried out of England.” In Paris, Petty made the acquaintance of Hobbes, who retired early from the civil wars. Hobbes soon discovered the capacity of his young friend, and read with him the Anatomy of Vesalius. He entered at Brazennose College, Oxford, in April, 1648, and took his degree there as Doctor of Physic, in March, 1649. The date of his admission to the College of Physicians is 25 June, 1650. He had been previously deputy to Doctor Thomas Clayton, Professor of Anatomy at Oxford, who laboured under the singular disqualification of having an insurmountable aversion to the sight of a mangled corpse. On the resignation of Clayton in 1651, Petty became Anatomical Professor, and about the same time he succeeded Dr. Knight in the Professorship of Music in Gresham College. About the year 1645, the Royal Society was formed, and Petty was one of the earliest members of the Oxford branch.