James Prescott Joule, English physicist, 1889. Joule (1818-1889) was born at Salford near Manchester and studied chemistry under John Dalton. His researches between 1843 and 1878 showed that heat is a form of energy. He was able to establish the mechanical equivalent of heat and the unit of energy, the Joule, is named for him. From The Graphic. (London, 1889). (Colorised black and white print).