Today, a story about blood and heat. The University
of Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
In 1840, Robert Mayer was
26. That year he shipped to the East Indies as the
surgeon on a Dutch vessel. Afterward, he came back
to Germany, married, and settled down as a town
doctor. It might seem he was done with adventure.
But something touched him in Java, and it changed
his life. Whether or not it changed history is
moot. But insight came on Mayer in 1840, and
science historians still talk about it.
He was letting blood from sick sailors. You do that
by lancing a vein. Venous blood carries less oxygen
than arterial blood. It runs darker. The first time
Mayer opened a vein in Djarkata, blood ran far too
red. He thought he'd hit an artery.
Then he found that's normal in the tropics. And he
realized: People burn less of the food they eat.
They generate less heat.
We knew that food fuels our power output. Now Mayer
realized that it also fuels our heat supply. And we
need a lot less heat in Djakarta than we do in
In 1840 we didn't know that heat and work can be
traded back and forth. Mayer thought about that red
blood on the long trip back. And he tumbled to the
truth of energy conservation.
Mayer identified our most important physical law.
But he didn't know classical physics. He didn't
know formal math. He wrote a clumsy paper about the
idea, and the editor ignored it.
So Mayer went back to study physics. Then he wrote
a better paper in 1842. Meanwhile, a young
Englishman, James Joule, was measuring how many
foot-pounds of work made a Btu. By 1847, Joule had
honed his accuracy to 99 percent.
And there the plot thickens. Mayer had spun a
correct theory for the number of foot-pounds per
Btu. But no one would believe it until measurements
were more complete.
Physicists sorted through Mayer's theory and
Joule's experiment. When they finally resolved the
whole business, they overlooked Mayer. By 1850
Mayer was angry and frustrated. He attempted
suicide. For years after, he was in and out of
Finally, in 1863, the Englishman John Tyndall wrote
an important text: Heat: A Mode of
Motion. It began and ended with Mayer. Mayer
Twenty years before, insight had touched him in
Java. His vision of bright blood and heat really
did change history. But first, professional
scientists -- men untouched by visions -- had to
put it in familiar terms. In the meantime, Mayer's
insight had almost driven him mad. And I hear words
by the poet Rilke:
I'm John Lienhard, at the University of
Houston, where we're interested in the way inventive
. . . if you set this brain of mine on
then on my blood I yet will carry you.
Lindsay, R.B., Julius Robert Mayer: Prophet of
Energy. New York: Pergamon Press, 1973.
Turner, R.S., Mayer, Julius Robert.
Dictionary of Scientific Biography.
Vol. ??, (C.C. Gilespie, ed.) Chas. Scribner's
Sons, 1970-1980. pp. 235-240.
Deickmann, F., Vor 150 Jahren: Robert Mayer und die
Erhaltung der Energie. Lufthansa
Bordbuch, March, 1991, pp. 52 and 54.
Rukeyser, M., Willard Gibbs. Garden
City, NY: Doubleday, Doran, and Co., 1942. (Poet
Muriel Rukeyser begins her biography of the
thermodynamicist J.W. Gibbs with an account of
Mayer's recognition of the conservation of energy
in the year after Gibbs was born.)
The Correlation and Conservation of Forces: A
Series of Expositions. (E.L. Youmans ed.).
New York: D. Appleton and Co., 1865.
Tyndall, J., Heat Considered as a Mode of
Motion. New York: D. Appleton and Co., 1863.
Rilke, R.M., Poems from the Book of
Hours (tr. B. Deutsch). New York: New
Directions Pub. Corp., 1941.
Today, Mayer is once again largely forgotten in
textbooks. We give most of the credit to Joule.
However, the building block of Mayer's theory was
that the conversion factor, J ft-lb/Btu, (or
dyne-cm/cal or N-m/J) could be obtained from,
R is the ideal gas constant expressed in
work units. Cp and Cv are the specific heats at
constant pressure and constant volume. They're
expressed in heat units.
J = R/(Cp - Cv)
Our textbooks simply write, R = Cp - Cv, and we
presume that students know how to convert heat and
work units. One problem with Mayer's work was that
he had an accurate value of R, but Cp and Cv data
were flawed. Therefore his value of J was far less
accurate than Joule's.
We call the law of conservation of energy the First
Law of Thermodynamics. It says energy is conserved
over its many forms -- potential, kinetic, thermal,
and so on. Energy can neither be created nor
destroyed. In 1850 another German, Clausius,
codified the law in the words, "Die energie der
Welt ist Konstant," where we take the word Welt to
mean universe, not world.
Today, of course, we amend the First Law to
acknowledge that matter and energy are also
interchangeable in nuclear reactions.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
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