Strange Success

The final episode in this life full of ironies will seem like the ultimate irony.
Recognition of Mayer’s achievements finally came, but hardly in a way deserved
by a man who had endured indifference, rejection, breakdown, cruel medical
treatment, and reports of his own death. In the early 1860s Mayer, now peacefully
tending his vineyards in Heilbronn, suddenly became the center of a famous
scientific controversy.
It all started when John Tyndall, a popular lecturer, professor, and colleague
of Michael Faraday at the Royal Institution in London, prepared himself for a
series of lectures on heat. He wrote to Hermann Helmholtz and Rudolf Clausius
in Germany for information. Included in Clausius’s response was the comment
that Mayer’s writings were not important. Clausius promised to send copies of
Mayer’s papers nevertheless, and before mailing the papers he read them, apparently
for the first time with care. Clausius wrote a second letter with an entirely
different assessment: “I must retract the statements in my last letter that
you would not find much of importance in Mayer’s writings; I am astonished at
the multitude of beautiful and correct thoughts which they contain.” Clausius
was now convinced that Mayer had been one of the first to understand the energy
concept and its conservation doctrine. Helmholtz also sent favorable comments
on Mayer, pointing especially to the early evaluation of the mechanical equivalent
of heat.
Tyndall was a man who loved controversy and hated injustice. Because his
ideas concerning the latter were frequently not shared by others who were
equally adept in the practice of public controversy, he was often engaged in
arguments that were lively, but not always friendly. When Tyndall decided to be
Mayer’s champion, he embarked on what may have been the greatest of all his
controversies. As usual, he chose as his forum the popular lectures at the Royal
Institution. He had hastily decided to broaden his topic from heat to the general
subject of energy, which was by then, in the 1860s, mostly understood; the title
of his lecture was “On Force.” (Faraday and his colleagues at the Royal Institution
still preferred to use the term “force” when they meant “energy.”)
Tyndall began by listing many examples of energy conversion and conservation,
and then summarized Mayer’s role with the pronouncement, “All that I have
brought before you has been taken from the labors of a German physician, named
Mayer.” Mayer should, he said, be recognized as one of the first thermodynamicists,
“a man of genius arriving at the most important results some time in advance
of those whose lives were entirely devoted to Natural Philosophy.” Tyndall
left no doubt that he felt Mayer had priority claims over Joule: “Mr. Joule published
his first paper ‘On the Mechanical Value of Heat’ in 1843, but in 1842
Mayer had actually calculated the mechanical equivalent of heat.” In the gentlemanly
world of nineteenth-century scientific discourse, this was an invitation to
verbal combat. It brought quickresponses from Joule and Thomson, and also
from Thomson’s close friend Peter Guthrie Tait, professor of natural philosophy
at the University of Edinburgh, and Tyndall’s match in the art of polemical
debate.
Joule was the first to reply, in a letter published in the Philosophical Magazine.
He could not, he said, accept the view that the “dynamical theory of heat” (that
is, the theory of heat that, among other things, was based on the heat-workconnection)
was established by Mayer, or any of the other authors who speculated on the meaning of the conversion processes. Reliable conclusions “require experiments,”
he wrote, “and I therefore fearlessly assert my right to the position
which has been generally accorded to me by my fellow physicists as having been
the first to give decisive proof of the correctness of this theory.”
Tyndall responded to Joule in another letter to the Philosophical Magazine,
protesting that he did not wish to slight Joule’s achievements: “I trust you will
find nothing [in my remarks] which indicates a desire on my part to question
your claim to the honour of being the experimental demonstrator of the equivalence
of heat and work.” Tyndall was willing to let Mayer speak for himself; at
Tyndall’s suggestion, Mayer’s papers on the energy theme were translated and
published in the Philosophical Magazine.
But this did not settle the matter. An article with both Thomson and Tait listed
as authors (although the style appears to be that of Tait) next appeared in a
popular magazine called Good Words, then edited by Charles Dickens. In it,
Mayer’s 1842 paper was summarized as mainly a recounting of previous work
with a few suggestions for new experiments; “a method for finding the mechanical
equivalent of heat [was] propounded.” This was, the authors declared, a
minor achievement, and they could find no reason to surrender British claims:
On the strength of this publication an attempt has been made to claim for Mayer
the credit of being the first to establish in all its generality the principle of the
Conservation of Energy. It is true that la science n’a pas de patrie and it is
highly creditable to British philosophers that they have so liberally acted according
to this maxim. But it is not to be imagined that on this account there
should be no scientific patriotism, or that, in our desire to do justice to a foreigner,
we should depreciate or suppress the claims of our countrymen.
Tyndall replied, again in the Philosophical Magazine, pointedly directing his
remarks to Thomson alone, and questioning the wisdom of discussing weighty
matters of scientific priority in the pages of a popular magazine. He now relaxed
his original position and saw Joule and Mayer more in a shared role:
Mayer’s labors have in some measure the stamp of profound intuition, which
rose, however, to the energy of undoubting conviction in the author’s mind.
Joule’s labours, on the contrary, are in an experimental demonstration. True to
the speculative instinct of his country, Mayer drew large and weighty conclusions
from slender premises, while the Englishman aimed, above all things, at
the firm establishment of facts. And he did establish them. The future historian
of science will not, I think, place these men in antagonism.
Tait was next heard from. He wrote to one of the editors of the Philosophical
Magazine, first offering the observation that if Good Words was not a suitable
medium for the debate of scientific matters, neither were certain popular lecture
series at the Royal Institution. He went on: “Prof. Tyndall is most unfortunate in
the possession of a mental bias which often prevents him . . . from recognizing
the fact that claims of individuals whom he supposes to have been wronged have,
before his intervention, been fully ventilated, discussed, and settled by the general
award of scientific men. Does Prof. Tyndall know that Mayer’s paper has no
claim to novelty or correctness at all, saving this, that by a lucky analogy he got
an approximation to a true result from an utterly false analogy?” Even if the polemics had been avoided, any attempt to resolve Joule’s and
Mayer’s conflicting claims would have been inconclusive. If the aim of the debate
was to identify once and for all the discoverer of the energy concept, neither
Joule nor Mayer should have won the contest. The story of the energy concept
does not end, nor does it even begin, with Mayer’s speculations and Joule’s experimental
facts. Several of Kuhn’s simultaneous discoverers were earlier, although
more tentative, than Joule and Mayer. In the late 1840s, after both men
had made their most important contributions, the energy concept was still only
about half understood; the modern distinction between the terms force and energy
had not even been made clear. Helmholtz, Clausius, and Thomson still had
fundamentally important contributions to make.
Those who spend their time fighting priority wars should forget their individual
claims and learn to appreciate a more important aspect of the sociology of
science: that the scientific community, with all its diversity cutting across race,
class, and nationality, can, as often as it does, arrive at a consensus acceptable
to all. The final judgment in the Joule-Mayer controversy teaches this lesson. In
1870, almost a decade after the last Tyndall or Tait outburst, the Royal Society
awarded its prestigious Copley medal to Joule—and a year later to Mayer.