recognition of this fact led Carnot, when but twenty-eight years old, to undertake to lay the foundation on which all future progress was to rest, by publishing in 1824 a small memoir, 'Reflexions sur la puissance motrice du feu' ('Reflections on the Motive Power of Heat'). George Stephenson made his wonderfully simple, but exceedingly effective, improvements in the locomotive from 1814 to 1829, at a time when the world was still ignorant of the value of Carnot's ideas. To-day, however, when physicists fully realize the importance of his work, the world at large is still ignorant of Carnot's biography; and so it is the purpose of this article to recall the life and character of him whose name must always be intimately associated with the development of the modern 'heat engine' and its influence upon civilization.
Carnot's father, Lazare Nicholas Marguerite Carnot, soldier and statesman, was a member of one of the oldest and most distinguished families in France. Educated as a military engineer, he gained a second lieutenancy at eighteen and in later life won renown as a mathematical writer. Minister of War under Napoleon, he took a prominent part in the French Revolution and was regarded by his countrymen as the genius and organizer of victory, exhibiting the talents later illustrated by the German, Von Moltke. He voted against the extension of the consulate and against the Empire, and was forced into private life in the early days of the latter and died, proscribed, at Magdeburg in 1823. Carnot's brother, Lazare Hippolyte Carnot, was twice a member of the Chamber of Deputies and also Minister of Public Instruction. He died as recently as 1888. A fact which brings Carnot's life still closer to us of to-day is that the late president of France, Sadi Carnot, who was assassinated in 1890, was a grand-nephew of the founder of thermodynamics, the subject of this sketch.
Nicholas-Leonard-Sadi Carnot was born June 1, 1796, in the smaller Luxembourg palace, a part of which was occupied by his father as a member of the Directory. Christened 'Sadi' after the celebrated Persian poet and moralist, he merited the name in that his nature proved to be highly artistic as well as philosophic. Hardly a year after Carnot's birth, in consequence of his father's proscription and enforced exile, his mother took refuge at her homestead in Saint Omer. The boy's delicate constitution was so affected by the vicissitudes of his mother's life that he regained his bodily powers later on only by judicious exercise. He was of medium stature, gifted with extreme sensibility and at the same time with extreme energy, generally reserved, sometimes timid, but singularly quick upon occasion. Whenever he believed that he was encountering injustice, nothing served to restrain him. An incident, which his brother has described, exhibits him in this light even as a child.