Joule
JAMES PRESCOTT, an English physicist; born in Salford, England, Dec. 24, 1818. He studied under Dalton the chemist, made researches into electromagnetism, about 1840 turned his atten- JOURDAN tion to the subject of heat, and ultimately established the theory of the mechanical equivalent of heat. His published work consists mainly of papers read before the Royal Society, of which he was made a fellow in 1850, receiving its medal in 1852, and the Copley medal in 1870. He received in 1878 a civil list pension of $1,000 in recognition of his services to science. His most important achievement was that of settling the mechanical equivalent of heat, which established that the quantity of heat capable of increasing the temperature of one pound of water 1° F. requires for its evolution the expenditure of mechanical energy represented by the fall of 772 pounds through the space of one foot. He died in Sale , Oct. 11, 1889. See JOULE'S LAW.