James Prescott Joule was born the son of a wealthy brewer in Salford, England, near Manchester. While working for the family business, he learned the importance of careful measurement, especially temperature. Joule was educated at home where among his private tutors was John Dalton.
Joule was active in the brewery business for years. Science began as a hobby, but became a serious study. He studied the nature of heat and discovered the relationship between heat and mechanical work. The SI unit of work, the joule, is named after him. He established the First Law of Thermodynamics (conservation of energy).
Joule died at home in Sale and is buried there. On his gravestone the number "772.55" is inscribed. This is his last measurement of the mechanical equivalent of heat.