Sadi Carnot (1796-1832), French physicist and founder of the science of thermodynamics. Carnot was interested in the amount of work that could be obtained from a heat engine. He demonstrated theoretically that the maximum possible efficiency depended on the difference in temperature between the hottest and coolest parts of the engine. This important result (the Carnot cycle) later led to Clausius's formulation of the second law of thermodynamics. Carnot died of cholera aged 36. His name is one of 72 inscribed on the Eiffel Tower. This coloured engraving, showing Carnot aged 17, is based on an 1813 portrait by Bailly.