On August 2nd 1 day, British physicist James Prescott Joule read out his paper "On Electromagnetic Thermal Effect and Mechanical Value of Heat" at an academic report meeting in Koukl, and published his experimental findings: a 838-pound weight lifting1foot in the vertical direction does equivalent mechanical work. Joule concluded that there is a constant proportional relationship between heat and mechanical work, and then calculated that the equivalent value of thermal work is 460 kg m 1 kcal, and the heat of1kcal is equivalent to 460 kg m mechanical work.