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

histories cites these (Hirn's) articles and even recognizes the existence of Hirn's
claim" 500.
In my view, for a correct grouping of the "pioneers", the acceptance of a
principle of conversion with constant coefficients or of a principle of
conservation of "energy" must be kept separate from the specific model adopted
for "energy", from the experimental determination of the work equivalent and,
finally, from the mathematical representation of the quantity conserved.
Helmholtz in fact thought possible to formulate the principle of conservation in
the Erhaltung with either heat models (caloric and mechanical), and the choice
in favour of the mechanical one was made on experimental grounds. I want also
to underline that the Erhaltung was largely independent from the experimental
determination of the work-heat equivalent: as I am going to show, Helmholtz did
not give much importance to Joule's (wrongly-translated) values. Finally,
mechanical theory is not the only route to the work-heat equivalence: Mayer
denied the first and determined the second.
The need for these distinctions is shown in Carnot's case. Kuhn asserts
that Sadi Carnot's Réflexions "are incompatible with energy conservation" and
"Carnot's version of the conservation hypothesis is scattered through a notebook
written between the publication of his memoir in 1824 and his death in 1832." 501.
Thus he considers Carnot as a pioneer of energy conservation for his
posthumously published acceptance of the mechanical model of heat and of the
relative determination of the work-heat equivalent (370Kgm) 502. But this result,
while obviously placing Carnot among the pioneers of the mechanical theory of
heat and of the determination of the work-heat equivalence, was not needed in
order to consider him among the followers of "energy conservation". Given that
Carnot correctly based his theory on the impossibility of perpetual motion, even
his published results do not contradict the principle of "energy" conservation.
They contradict the mechanical model of heat: Carnot's assumed an interpretation
of "energy" (heat by temperature variation, and this "energy" equals work) that
later was abandoned because the conceptual model of heat adopted (heat as a
substance) was shown to be experimentally wrong. The soundness of Carnot's
500 Kuhn Sim Disc P.68 n.2.
501 Kuhn Sim Disc P.93 and 67 respectively.
502 At the same time Kuhn asserts that, strictly speaking, Holtzmann, who also used
the caloric theory, should not be included in the list. However Kuhn includes him because he
made a determination similar to Mayer's one. Ibid p.67, n.2.