BROUNCKER, WILLIAM, lord viscount of Castlelyons, in Ireland, and the first president of the Royal Society, was the son of Sir William Brouncker, and was born about 1620. He was distinguished by his knowledge of mathematics, and enjoyed various posts of honour and profit after the Restoration; for he was at the same time chancellor to the queen, keeper of the great seal, a commissioner of the navy, and master of St Catherine's Hospital, near the Tower of London. Amongst other works he wrote Experiments on the recoiling of Guns; An algebraical paper upon the squaring of the Hyperbola; and several letters to Dr Usher, archbishop of Armagh. He died in 1684.