Stephen Hales

Stephen Hales (1677 to 1761) was an English clergyman who made major contributions to botany, pneumatic chemistry and physiology. Born in Bekesbourne, Kent, he studied at Corpus Christi College, Cambridge, where he became a Fellow in 1703, and from 1709 he was perpetual curate of Teddington, Middlesex, where he stayed for the rest of his life. He was the first person to measure blood pressure, and he invented several devices, among them a ventilator, a pneumatic trough and a surgical forceps for removing bladder stones. In Vegetable Staticks of 1727 he described experiments in plant physiology and chemistry, including his study of transpiration, the loss of water from the leaves of plants. Elected a fellow of the Royal Society in 1718, he received the Copley Medal in 1739, and he was also known as a philanthropist and as a campaigner against the gin trade.