or Broucker, William, lord viscount of Caillé-Lyons, in Ireland, and the first president of the Royal Society, was the son of Sir William Broucker, knt. and born about the year 1620. He was distinguished by his knowledge of the mathematics, and by the considerable posts of honour and profit he enjoyed after the restoration; for he had at the same time the office of chancellor to the queen, and the keeping of her great seal, that of one of the commissioners of the navy, and master of St Catharine's hospital near the Tower of London. He wrote, 1. Experiments of the recoiling of guns. 2. An algebraical paper upon the squaring of the hyperbola; and several letters to Dr Ulher, archbishop of Armagh. He died in 1684.