Sir William Petty Petty, Sir William, 1623?7, English statistician and physician. He was a founder of the Royal Society and was physician general to the army of Ireland in 1652. Petty's survey of the Irish estates appropriated by Oliver Cromwell, begun in 1654 and carried out in 13 months, was the first attempt at scientific surveying on a large scale. He won favor with Charles II, was knighted (1662), and became surveyor general of Ireland. In 1673, Petty's detailed map of Ireland was completed. It is as a political economist, however, that Petty is remembered. He disapproved of the ban on bullion export, favored an Irish-British union, and contended that labor determines price. His important writings include A Treatise on Taxes and Contributions (1662) and The Political Anatomy of Ireland (1691).