“[T]he production of heat alone is not sufficient to give birth to the impelling power: it is necessary that there should also be cold; without it, the heat would be useless.”

French military engineer and physicist

Nicolas Léonard Sadi Carnot, known as Sadi Carnot, was a French military engineer and physicist. He was active in the early 19th century and is remembered for his work on the science of heat. A graduate of the École polytechnique, he served as an officer in the Engineering Arm of the French Army while also pursuing scientific study. In June 1824, he published Reflections on the Motive Power of Fire, his only book, where he set out the first successful theory of the maximum efficiency of heat engines.