Conservation and Innovation : Helmholtz's Struggle with Energy ...

not being explicitly formulated, was already in the background (of the vis viva
conservation) for conservative forces: in this case work cannot be destroyed. The
problem of the nature of heat helped, through many difficulties, to gain wide
acceptance for the second philosophical root. At the beginning of the forties the
existence of the caloric was widely questioned, not only in scientific debates:
Helmholtz himself recalls an essay on the topic that he had to write when a
student at the Potsdam Gymnasium. Apparently here Helmholtz forgets his own
difficulties in giving up with the caloric in his first papers. He again defines his
Erhaltung not as an original research but as a critical survey, aimed at clarifying
and reordering known facts and deciding between different explanations.
Mayer was not, then, completely original even if his paper of 1842
deserves due credit. But the credit is for the priority in the assertion of an idea,
not for his demonstration. Without an empirical demonstration of the
indestructibility of forces, the " deduction" from obscure metaphysical principles
as "causa aequat effectum" is worthless. Mayer did not give this empirical
evidence in 1842 (he did not explain but only asserted that the work equivalent
was 365 kgm). But even if he had explained his calculation of the work
equivalent he would not have shown anything: "it was necessary to show that
different processes give the same value". The accomplishment of this great
experimental task is the lasting merit of Joule.
Helmholtz becomes more and more severe: only after Joule's work do
Mayer's views acquire the character of "non improbable hypotheses" 363 and
Mayer's destiny teaches young researchers that the best ideas risk to be sterile
without convincing demonstrations.
The priority debate was actually a debate on scientific methodology, as
almost explicitly asserted by Helmholtz. Both in the undervaluation of his own
contribution of 1847 and of Mayer's results Helmholtz clearly shows that in the
early eighties the preoccupations with an empiricist viewpoint were very strong.
Was this due to the bitter controversy that even led him into a depressive state 364
or are its roots to be found in real scientific problems resulting from his previous
theoretical commitments? Helmholtz's original approach to energy conservation
had in fact been seriously challenged in the electrodynamics debates of the
seventies.
363 Helmholtz
364 Koenigsberger H v H p.306.