( 583 ) 
respond with the total number of degrees of freedom. So this agrees 
with what we observe with regard to specifie heat. 
An ovjection to this theory is, that it is inexplicable how such a 
system could be. heated by radiation. For then the dissipative coor- 
dinates would first absorb heat, and then transfer it to the conser- 
vative coordinates. But they can only transfer it, when on an 
average they have more kinetic energy than the conservative coor- 
dinates. So if such a body was exposed to the radiation of a hotter 
body, it would absorb very much heat before the temperature began 
to rise, and on further heating by radiation the dissipative coordinates, 
too, would have to receive energy, and the specific heat would 
therefore be greater than when the heating was done by conduction. 
On account of these and similar conclusions which might be made 
from JEANS’s theory, this theory did not seem satisfactory. 
Finally in Pranck’s theory it is not possible to ascertain which 
of the three suppositions is to be rejected. Still it is clear that we 
can never obtain PLANck’s spectral formula, if we accept the three 
suppositions. His suppositions must, therefore, be incompatible with 
the three suppositions given here, and probably the hypothesis that 
the energy can only be absorbed in fixed energy-quanta, will be 
irreconcilable with our suppositions. Of course, this is no objection 
to PrANCK's theory; the assumption of the three suppositions bringing 
us into conflict with experience, one of them must in reality not be 
fulfilled. © Of more importance seems to me the objection that the 
supposition of these fixed quanta of energy which can only be 
absorbed or radiated as a whole, and which, moreover, have a 
different amount for radiation of different wave-length, clash altogether 
with all our ideas on the behaviour of vibrators, and that it is 
difficult to see how it could be reconciled to the ordinary laws of 
radiation by vibrators, of which PranckK also made use in his theory. 
Nor would this objection perhaps suffice to make us reject the 
theory, when there were urgent reasons why we should have to 
assume .the existence of these energy-quanta. In my opinion, however, 
these urgent reasons are wanting. PLanck used the supposition of the 
existence of these energy-quanta to bring two equations into harmony, 
which have been derived in an entirely different way. One’) has 
been derived from the laws of BOLTZMANN (STEPHAN) and Wien, which 
are again derived from the 2°¢ law of thermodynamics in connection 
with the fundamental equations of the theory of electricity, and 
which, therefore, hold for all the systems for which these laws hold. 
1) M. Pranck. Vorlesungen über die Theorie der Warmestrahlung p. 149 equation 223, 
