ASHRAE Journal - June 2024 - 44

FEATURE
Sir William Thomson presented a review of Carnot's
Reflections to the Edinburgh Royal Society in 1849. He
had spent a year studying with Regnault in Paris after
graduating from Cambridge University, assisting in
Regnault's experiments on the properties of gases
and noted that this provided the empirical data that
Carnot had lacked. Thomson wrote, " M. Regnault
informs me that he is engaged in completing some
researches, from which we may expect, possibly
before the end of the present year, to be furnished
with all the data for five or six different liquids which
we possess at present for water. It is therefore to be
hoped that, before long, a most important test of
the validity of Carnot's theory will be afforded. " 2 A
summary of Carnot's ideal heat engine cycle, with
comparisons to two alternatives, is given in the
sidebar, " Comparison of Ideal Cycles. "
Apart from his scientific and engineering studies
from the age of 22 onward, Sadi Carnot was widely
read and enjoyed physical sports as well as being an
accomplished musician, playing piano and violin.
A measure of his character can be gained from the
aphorisms jotted in his notebooks., which give the
impression of a modest man, not keen to take center
stage but happy to share a joke with friends. Some
of these musings are given in the sidebar, " The
Many Facets of Sadi-Quotations from His Personal
Notebooks. " His brother, Hippolyte, 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.2 Sadi himself
wrote, " The time passed in laughing is well spent. "
After publishing Reflections in 1824, Carnot continued
his studies, rising to the `rank` of Captain in the Army
then leaving the service in 1828 to devote himself
to science, working with Clément and Desormes to
develop the data necessary to confirm his propositions.
This work was interrupted in 1830 by another
revolution, which deposed King Charles X, brother of
Louis XVIII, and replaced him with his cousin, Louis
Philippe I. The unrest continued and in June 1832 the
death of General Jean Lamarque led to widespread
rioting and rebellion among students in Paris, as
portrayed in the novel Les Misérables by Victor Hugo and
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ASHRAE JOURNAL ashrae.org J U N E 2024
its musical adaptation. Hippolyte Carnot explains that
despite his intensive study his brother had retained the
cool self-control of the sportsman-soldier.
" On the day of the funeral of General Lamarque (June
5), 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 avoiding
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. " 2
Later that month, he fell ill with pneumonia and
scarlet fever. This sickness lasted over a month,
including twelve days in bed without sleep or food, and
left him weak. By the end of July, he felt his strength
gradually returning but within a few weeks, still weak,
he contracted cholera and died on August 24.
Acknowledgments
The ASHRAE Historical Committee encouraged the
creation of this article to mark the bicentenary of
Carnot's original publication. Particular thanks are
due to Bern Nagengast, a long-serving member of
the Historical Committee, and Bob Hanlon for their
encouragement to see these refrigeration pioneers as
real people with real lives rather than one-dimensional
names in a textbook. Thanks also to Jon Fenton, who
encouraged me to read Reflections on the Motive Power
of Fire and on Machines Fitted to Develop that Power and to
discover what a remarkable feat it is.
References
1. Carnot, Sadi and Robert Thurston. 1890. " Reflections on
the Motive Power of Fire and on Machines Fitted to Develop that
Power. " Cornell University.
2. Thomson, William. 1890. " An Account of Carnot's Theory of
the Motive Power of Heat - with Numerical Results Deduced from
Regnault's Experiments on Steam. " Transactions of the Edinburgh Royal
Society, volume xvi. Cambridge University Press.
Bibliography
1. Carnot, Hippolyte and Robert Thurston. 1890. " The life of N-L
Sadi Carnot. " Cornell University.
2. Hanlon, Robert T. 2020. " Block by Block: The Historical and
Theoretical Foundations of Thermodynamics. " Oxford University
Press.
3. Meckler, Gershon. 1994. " Scientific Roots of HVAC&R. " Heat
and Cold Mastering the Great Indoors. American Society of Heating,
Refrigerating and Air-Conditioning Engineers.
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