James Prescott Joule
Joule had no formal scientific training, but he did work for a short time under John Dalton. In spite of his meager schooling, he was able to make important scientific advances because he realized very early the absolute necessity for accurate measurement and exact data.
Experts feel that James Joule did more than any other scientist to establish the basic theories of energy. He also proved that heat is a form of energy. He showed that when work is done by a machine or electric current, an amount of energy is released equal to the amount of work done. Thus a joule is a unit of work or energy, a unit
equal to ten million ergs. It is approximately equal to 0.738 foot pound, or 0.24 small calorie. However, the joule is too small a unit of measure to use commercially. Consequently, kilowatt-hours — a larger unit of measure — has replaced the joule in common use.