As the life of Sadi Carnot was not marked by any notable event, his
biography would have occupied only a few lines; but a scientific work by
him, after remaining long in obscurity, brought again to light many
years after his death, has caused his name to be placed among those of
great inventors. In regard to his person, his mind, his character,
nothing whatever has been known. Since there remains a witness of his
private life—the sole witness, has he not a duty to fulfil? Ought he not
to satisfy the natural and legitimate interest which attaches to any man
whose work has deserved a portion of glory?
Nicolas-Léonard-Sadi Carnot was born June 1, 1796, in the smaller
Luxembourg. This was that part of the palace where our father then dwelt
as a member of the Directory. Our father had a predilection for the name
of Sadi, which recalled to his mind ideas of wisdom and poetry. His
firstborn had borne this name, and despite the fate of this poor child,
who lived but a few months, he called the second also Sadi, in memory of
the celebrated Persian poet and moralist.
Scarcely a year had passed when the proscription, which included the
Director, obliged him to give up his life, or at least his liberty, to
the conspirators of fructidor. Our mother carried her son far from the
palace in which violation of law had just triumphed. She fled to St.
Omer, with her family, while her husband was exiled to Switzerland, then
to Germany.
Our mother often said to me, “Thy brother was born in the midst of the
cares and agitations of grandeur, thou in the calm of an obscure
retreat. Your constitutions show this difference of origin.”
My brother in fact was of delicate constitution. He increased his
strength later, by means of varied and judicious bodily exercises. He
was of medium size, endowed with extreme sensibility and at the same
time with extreme energy, more than reserved, almost rude, but
singularly courageous on occasion. When he felt himself to be contending
against injustice, nothing could restrain him. The following is an
anecdote in illustration.
The Directory had given place to the Consulate. Carnot, after two years
of exile, returned to his country and was appointed Minister of War.
Bonaparte at the same time was still in favor with the republicans. He
remembered that Carnot had assisted him in the beginning of his military
career, and he resumed the intimate relation which had existed between
them during the Directory. When the minister went to Malmaison to work
with the First Consul, he often took with him his son, then about four
years old, to stay with Madame Bonaparte, who was greatly attached to
him.
She was one day with some other ladies in a small boat on a pond, the
ladies rowing the boat themselves, when Bonaparte, unexpectedly
appearing, amused himself by picking up stones and throwing them near
the boat, spattering water on the fresh toilets of the rowers. The
ladies dared not manifest their displeasure, but the little Sadi, after
having looked on at the affair for some time, suddenly placed himself
boldly before the conqueror of Marengo, and threatening him with his
fist, he cried “Beast of a First Consul, will you stop tormenting those
ladies!”
Bonaparte, at this unexpected attack, stopped and looked in astonishment
at the child. Then he was seized with a fit of laughter in which all the
spectators of the scene joined.
At another time, when the minister, wishing to return to Paris, sought
his son, who had been left with Madame Bonaparte, it was discovered that
he had run away. They found him a long way off, in a mill, the mechanism
of which he was trying to understand. This desire had been in the
child’s mind for days, and the honest miller, not knowing who he was,
was kindly answering all his questions. Curiosity, especially in regard
to mechanics and physics, was one of the essential traits of Sadi’s
mind.
On account of this disposition so early manifested, Carnot did not
hesitate to give a scientific direction to the studies of his son. He
was able to undertake this task himself when the monarchical tendencies
of the new government had determined him to retire. For a few months
only Sadi followed the course of M. Bourdon at the Charlemagne Lycée to
prepare himself for the Polytechnic School.
The pupil made rapid progress. He was just sixteen years old when he was
admitted to the school, the twenty-fourth on the list. This was in 1812.
The following year he left it, first in artillery. But he was considered
too young for the school of Metz, and he continued his studies at Paris
for a year. To this circumstance is due the fact that he took part in
March, 1814, in the military exploits of Vincennes, and not of the butte
Chaumont, as almost all the historians of the siege of Paris declared.
M. Chasles, one of Sadi’s school-fellows, took pains to rectify this
error at a séance of the Institute in 1869.
If the pupils of the Polytechnic School did not earlier enter into the
campaign, it was not because they had not asked to do so. I find in my
brother’s papers the copy of an address to the Emperor, signed by them
December 29, 1813:
“SIRE: The country needs all its defenders. The pupils of the
Polytechnic School, faithful to their motto, ask to be permitted to
hasten to the frontiers to share the glory of the brave men who are
consecrating themselves to the safety of France. The battalion, proud of
having contributed to the defeat of the enemy, will return to the school
to cultivate the sciences and prepare for new services.”
General Carnot was at Anvers, which he had just been defending against
the confederate English, Prussians, and Swedes, where the French flag
yet floated, when he wrote to his son, April 12, 1814:
“MY DEAR SADI: I have learned with extreme pleasure that the battalion
of the Polytechnic School has distinguished itself, and that you have
performed your first military exploits with honor. When I am recalled, I
shall be very glad if the Minister of War will give you permission to
come to me. You will become acquainted with a fine country and a
beautiful city, where I have had the satisfaction of remaining in peace
while disaster has overwhelmed so many other places.”
Peace being restored, Sadi rejoined his father at Anvers and returned
with him into France.
In the month of October he left the Polytechnic School, ranking sixth on
the list of young men destined to service in the engineer corps, and
went to Metz as a cadet sub-lieutenant at the school. Many scientific
papers that he wrote there were a decided success. One is particularly
referred to as very clever, a memoir on the instrument called the
_theodolite_ which is used in astronomy and geodesy.
I obtain these details from M. Ollivier, who was of the same rank as
Sadi and who, later, was one of the founders of the _École Centrale_.
Among his other comrades besides M. Chasles, the learned geometrician
just now referred to, was Gen. Duvivier, lamented victim of the
insurrection of June 1848. I ought also to mention M. Robelin, Sadi’s
most intimate friend, who came to help me nurse him during his last
illness, and who published a notice concerning him in the _Revue
encyclopédique_, t. lv.
The events of 1815 brought General Carnot back into politics during the
“_Cent Jours_” which ended in a fresh catastrophe.
This gave Sadi a glimpse of human nature of which he could not speak
without disgust. His little sub-lieutenant’s room was visited by certain
superior officers who did not disdain to mount to the third floor to pay
their respects to the son of the new minister.
Waterloo put an end to their attentions. The Bourbons re-established on
the throne, Carnot was proscribed and Sadi sent successively into many
trying places to pursue his vocation of engineer, to count bricks, to
repair walls, and to draw plans destined to be hidden in portfolios. He
performed these duties conscientiously and without hope of recompense,
for his name, which not long before had brought him so many flatteries,
was henceforth the cause of his advancement being long delayed.
In 1818 there came an unlooked-for royal ordinance, authorizing the
officers of all branches of the service to present themselves at the
examinations for the new corps of the staff. Sadi was well aware that
favor had much more to do with this matter than ability, but he was
weary of garrison life. The stay in small fortresses to which the nature
of his work confined him did not offer sufficient resources to his love
of study. Then he hoped, and his hope was realized, that a request for a
furlough would be obtained without difficulty, and would insure him the
leisure that he sought. In spite of the friendly opposition of some
chiefs of the engineer corps, testifying to a sincere regret at the
removal from their register of a name which had gained honor among them,
Sadi came to Paris to take the examination, and was appointed lieutenant
on the staff, January 20, 1819.
He hastened to obtain his furlough, and availed himself of it to lead,
in Paris and in the country round about Paris, a studious life
interrupted but once, in 1821, by a journey to Germany to visit our
father in his exile at Magdeburg. We had then the pleasure of passing
some weeks all three together.
When, two years later, death took from us this revered father and I
returned alone to France, I found Sadi devoting himself to his
scientific studies, which he alternated with the culture of the arts. In
this way also, his tastes had marked out for him an original direction,
for no one was more opposed than he to the traditional and the
conventional. On his music-desk were seen only the compositions of Lully
that he had studied, and the concerti of Viotti which he executed. On
his table were seen only Pascal, Molière, or La Fontaine, and he knew
his favorite books almost by heart. I call this direction original,
because it was anterior to the artistic and literary movement which
preceded the revolution of 1830. As to the sympathy of Sadi for the
author of the _Provinciales_, it was due not only to the respect of the
young mathematician for one of the masters of science, but his devoutly
religious mind regarded with horror hypocrisy and hypocrites.
Appreciating the useful and the beautiful, Sadi frequented the museum of
the Louvre and the Italian Theatre, as well as the Jardin des Plantes
and the Conservatoire des Arts et Metiers. Music was almost a passion
with him. He probably inherited this from our mother, who was an
excellent pianist, to whom Dalayrac and especially Monsigny, her
compatriot, had given instruction. Not content with being able to play
well on the violin, Sadi carried to great length his theoretical
studies.
His insatiable intellect, moreover, would not allow him to remain a
stranger to any branch of knowledge. He diligently followed the course
of the College of France and of the Sorbonne, of the École des Mines, of
the Museum, and of the Bibliothèque. He visited the workshops with eager
interest, and made himself familiar with the processes of manufacture;
mathematical sciences, natural history, industrial art, political
economy,—all these he cultivated with equal ardor. I have seen him not
only practise as an amusement, but search theoretically into,
gymnastics, fencing, swimming, dancing, and even skating. In even these
things Sadi acquired a superiority which astonished specialists when by
chance he forgot himself enough to speak of them, for the satisfaction
of his own mind was the only aim that he sought.
He had such a repugnance to bringing himself forward that, in his
intimate conversations with a few friends, he kept them ignorant of the
treasures of science which he had accumulated. They never knew of more
than a small part of them. How was it that he determined to formulate
his ideas about the motive power of heat, and especially to publish
them? I still ask myself this question,—I, who lived with him in the
little apartment where our father was confined in the Rue du Parc-Royal
while the police of the first Restoration were threatening him. Anxious
to be perfectly clear, Sadi made me read some passages of his manuscript
in order to convince himself that it would be understood by persons
occupied with other studies.
Perhaps a solitary life in small garrisons, in the work-room and in the
chemical laboratory, had increased his natural reserve. In small
companies, however, he was not at all taciturn. He took part voluntarily
in the gayest plays, abandoning himself to lively chat. “The time passed
in laughing is well spent,” he once wrote. His language was at such
times full of wit, keen without malice, original without eccentricity,
sometimes paradoxical, but without other pretension than that of an
innocent activity of intelligence. He had a very warm heart under a cold
manner. He was obliging and devoted, sincere and true in his dealings.
Towards the end of 1826, a new royal ordinance having obliged the staff
lieutenants to return to the ranks, Sadi asked and obtained a return to
the engineer corps, in which he received the following year, as his rank
of seniority, the grade of captain.
Military service, however, weighed upon him. Jealous of his liberty, in
1828, he laid aside his uniform that he might be free to come and go at
will. He took advantage of his leisure to make journeys and to visit our
principal centres of industry.
He frequently visited M. Clement Desormes, professor at the
_Conservatoire des Arts et Metiers_, who had made great advances in
applied chemistry. M. Desormes willingly took counsel with him. He was a
native of Bourgogne, our family country, which circumstance, I believe,
brought them together.
It was before this period (in 1824) that Sadi had published his
_Réflexions sur la puissance motrice du feu_. He had seen how little
progress had been made in the theory of machines in which this power was
employed. He had ascertained that the improvements made in their
arrangement were effected tentatively, and almost by chance. He
comprehended that in order to raise this important art above empiricism,
and to give it the rank of a science, it was necessary to study the
phenomena of the production of motion by heat, from the most general
point of view, independently of any mechanism, of any special agent; and
such had been the thought of his life.
Did he foresee that this small brochure would become the foundation of a
new science? He must have attached much importance to it to publish it,
and bring himself out of his voluntary obscurity.
In fact (as his working notes prove), he perceived the existing relation
between heat and mechanical work; and after having established the
principle to which savants have given his name, he devoted himself to
the researches which should enable him to establish with certainty the
second principle, that of equivalence, which he already clearly divined.
Thermodynamics was established from that time.
But these researches were rudely interrupted by a great event—the
Revolution of July, 1830.
Sadi welcomed it enthusiastically—not, however, it is evident, as a
personal advantage.
Several old members of the Convention were still living, even of those
who had become celebrated; no favor of the new government was accorded
them. To the son of Philippe-Egalité was ascribed a saying which, if it
was untrue, at least agreed well with the sentiment of his position: “I
can do nothing for the members of the Convention themselves,” he said,
“but for their families whatever they will.”
However it may be, some of those about him vaguely questioned my brother
as to his desires in case one of us should be called to the Chamber of
Peers, of which Carnot had been a member in 1815. We had on this
occasion a brief conference. Unknown to us both, this distinction could
be offered only to a title in some sort hereditary. We could not accept
it without forsaking the principles of Carnot, who had combated the
heredity of the peerage. The paternal opinion therefore came to second
our distaste for the proposition, and dictated our reply.
Sadi frequented the popular reunions at this period without forsaking
his _rôle_ of a simple observer.
Nevertheless he was, when occasion demanded it, a man of prompt and
energetic action. One incident will suffice to prove this, and to show
the _sang-froid_ which characterized him.
On the day of the funeral of Gen. Lamarque, Sadi was walking
thoughtfully in the vicinity of the insurrection. A horseman preceding a
company, and who was evidently intoxicated, passed along the street on
the gallop, brandishing his sabre and striking down the passers-by. Sadi
darted forward, cleverly avoided the weapon of the soldier, seized him
by the leg, threw him to the earth and laid him in the gutter, then
continued on his way to escape from the cheers of the crowd, amazed at
this daring deed.
Before 1830, Sadi had formed part of a _Réunion polytechnique
industrielle_, made up of old pupils of the school, with a plan of study
in common. After 1830, he was a member of the _Association
polytechnique_, consisting also of graduates, the object being the
popular propagation of useful knowledge. The president of this
association was M. de Choiseul-Praslin; the vice-presidents, MM. de
Tracy, Auguste Comte, etc.
The hopes of the democracy meanwhile seeming to be in abeyance, Sadi
devoted himself anew to study, and pursued his scientific labors with
all the greater energy, as he brought to bear upon them the political
ardor now so completely repressed. He undertook profound researches on
the physical properties of gases and vapors, and especially on their
elastic tensions. Unfortunately, the tables which he prepared from his
comparative experiments were not completed; but happily the excellent
works of Victor Regnault, so remarkable for their accuracy, have
supplied to science, in this respect, the blanks of which Sadi Carnot
was conscious.
His excessive application affected his health towards the end of June,
1832. Feeling temporarily better, he wrote gayly to one of his friends
who had written several letters to him: “My delay this time is not
without excuse. I have been sick for a long time, and in a very
wearisome way. I have had an inflammation of the lungs, followed by
scarlet-fever. (Perhaps you know what this horrible disease is.) I had
to remain twelve days in bed, without sleep or food, without any
occupation, amusing myself with leeches, with drinks, with baths, and
other toys out of the same shop. This little diversion is not yet ended,
for I am still very feeble.”
This letter was written at the end of July.
There was a relapse, then brain fever; then finally, hardly recovered
from so many violent illnesses which had weakened him morally and
physically, Sadi was carried off in a few hours, August 24, 1832, by an
attack of cholera. Towards the last, and as if from a dark presentiment,
he had given much attention to the prevailing epidemic, following its
course with the attention and penetration that he gave to everything.
Sadi Carnot died in the vigor of life, in the brightness of a career
that he bade fair to run with glory, leaving memory of profound esteem
and affection in the hearts of many friends.
His copy-books, filled with memoranda, attest the activity of his mind,
the variety of his knowledge, his love of humanity, his clear sentiments
of justice and of liberty. We can follow therein the traces of all his
various studies. But the only work that he actually completed is this
which is here published. It will suffice to preserve his name from
oblivion.
His moral character has other claims on our recognition. Our only
ambition here is to present a sketch of it. But, much better than
through the perusal of these few pages, Sadi Carnot can be appreciated
by reading the thoughts scattered through his memoranda, which are to be
carefully collected. There are many practical rules of conduct which he
records for himself; many observations that he desires to fix in his
memory; sometimes an impression that has just come to him, grave or gay;
sometimes too, though rarely, a trace of ill-humor directed against men
or society. He never thought that these notes, the outpouring of his
mind, would be read by other eyes than his own, or that they would some
day be used to judge him. I find in them, for my part, touching
analogies with the thoughts of my father, although the father and son
had, unfortunately, lived almost always apart, by force of
circumstances.[3]
III.
REFLECTIONS ON THE MOTIVE POWER OF HEAT, AND ON MACHINES FITTED TO
DEVELOP THAT POWER.[4]