The French physicist Nicolas Léonard Sadi Carnot (1796-1832), with his analysis of the working of an ideal heat engine, opened the road to the science of thermodynamics.

Sadi Carnot was born on June 1, 1796, in Paris. He was given the name Sadi because of the admiration of his father, Lazare Carnot, for Sadi (Muslihal-Din), a medieval Persian poet and moralist. Sadi entered the famed Polytechnique at the age of 16, and he graduated first the next year in the artillery section. In 1814 he went to Antwerp, where his father fought the British, made a successful stand against them, and became the only undefeated French general, as other Napoleonic armies fell to the Allies.

Following the peace treaty of 1814, father and son returned to Paris and from there Sadi went to Metz, where in the military school he wrote an able analysis of the use of theodolites. After Waterloo...