Robert Boyle (1627-1691), Irish chemist. Boyle was born at Lismore Castle, the seventh son of the 1st Earl of Cork. He was sent to Eton at the age of seven, leaving three years later to tour Europe with his tutor. Boyle established chemistry as a separate science and stressed the need for experimental precision and accurate observation. He rejected the theory that four elements (fire, air, water and earth) were the basic constituents of the Universe and postulated that there were a large number of 'elements' which could not be broken down into simpler chemicals. He formulated Boyle's law, which states that for a gas at a constant temperature the product of its pressure and volume is a constant. This engraving by Vertue comes from Birch's The Heads of Illustrious Persons of Great Britain, published at London in 1747.