James Prescott Joule
1818–1889, Salford, England, Sale, England
Thermal physics
English physicist who established the mechanical equivalent of heat, laying the experimental foundation for the first law of thermodynamics.
Joule, a brewery owner, personally conducted meticulous experiments measuring the heat generated when mechanical work was done (for instance, a falling weight turning a paddle wheel in water, measuring the resulting temperature rise). His results showed heat and work convert into each other at a fixed ratio, directly supporting the principle of energy conservation.
United Kingdom