Recognition

So, in the end, Sadi Carnot’s theory was resurrected, understood, and used. And
it finally became clear that Carnot, no less than his father Lazare, should be
celebrated as a great revolutionary. Born into a political revolution, Carnot started
a scientific revolution. His theory was radically new and completely original.
None of Carnot’s predecessors had exploited, or even hinted at, the idea that heat
fall was the universal driving force of heat engines.
If Carnot’s contemporaries lacked the vision to appreciate his work, his numerous
successors have, at least for posterity, repaired the damage of neglect.
Science historians now regard Carnot as one of the most inventive of scientists.
In his history of thermodynamics, From Watt to Clausius, Donald Cardwell assesses
for us Sadi Carnot’s astonishing success in achieving Lazare Carnot’s grand
goal, the abstraction of general physical principles from the complexities of machinery:
“Perhaps one of the truest indicators of Carnot’s greatness is the unerring
skill with which he abstracted, from the highly complicated mechanical contrivance
that was the steam engine . . . the essentials, and the essentials alone, of
his argument. Nothing unnecessary is included, and nothing essential is missed
out. It is, in fact, very difficult to thinkof a more efficient piece of abstraction in
the history of science since Galileo taught . . . the basis of the procedure.”Scant records of Carnot’s life and personality remain. In the two published
portraits, we see a sensitive, intelligent face, with large eyes regarding us with a
steady, slightly melancholy gaze. Most of the biographical material on Carnot
comes from a brief article written by Sadi’s brother Hippolyte. (Lazare Carnot
was partial to exotic names for his sons.) Hippolyte’s anecdotes tell of Carnot’s
independence and courage, even in childhood. As a youngster, he sometimes
accompanied his father on visits to Napoleon’s residence; while Lazare and Bonaparte
conducted business, Sadi was put in the care of Madame Bonaparte. On
one occasion, she and other ladies were amusing themselves in a rowboat on a
pond when Bonaparte appeared and splashed water on the rowers by throwing
stones near the boat. Sadi, about four years old at the time, watched for a while,
then indignantly confronted Bonaparte, called him “beast of a First Consul,” and
demanded that he desist. Bonaparte stared in astonishment at his tiny attacker,
and then roared with laughter.
The child who challenged Napoleon later entered the E´ cole Polytechnique at
about the same time the French military fortunes began to collapse. Two years
later Napoleon was in full retreat, and France was invaded. Hippolyte relates that
Sadi could not remain idle. He petitioned Napoleon for permission to form a
brigade to fight in defense of Paris. The students fought bravely at Vincennes,
but Paris fell to the Allied armies, and Napoleon was forced to abdicate.
Hippolyte records one more instance of his brother’s courage. Sadi was walking
in Paris one day when a mounted drunken soldier galloped down the street,
“brandishing his saber and striking down passers-by.” Sadi ran forward, dodged
the sword and the horse, grabbed the soldier, and “laid him in the gutter.” Sadi
then “continued on his way to escape from the cheers of the crowd, amazed at
this daring deed.”
Sadi Carnot lived in a time of unsurpassed scientific activity, most of it centered
in Paris. The list of renowned physicists, mathematicians, chemists, and
engineers who worked in Paris during Carnot’s lifetime includes Pierre-Simon
Laplace, Andre´-Marie Ampe`re, Augustin Fresnel, Sime´on-Denis Poisson, Adrien-
Marie Legendre, Pierre Dulong, Alexis Petit, Evariste Galois, and Gaspard de
Coriolis. Many of these names appeared on the roll of the faculty and students
at the E´ cole Polytechnique, where Carnot received his scientific training. Except
as a student, Carnot was never part of this distinguished company. Like some
other incomparable geniuses in the history of science (notably, Gibbs, Joule, and
Mayer in our story), Carnot did his important workas a scientific outsider. But
there is no doubt that Carnot’s name belongs on anyone’s list of great French
physicists. He may have been the greatest of them all.