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the solution of which would bring us an important step nearer to 
the drawing up of the new system of mechanics. 
Some phenomena are at present often considered in connection 
with the quanta-hypothesis of which it is not clear from the above 
how they are connected with the new system of mechanics, from 
which we expect the solution of the question concerning the partition 
of energy. Specially this is the case with the question of the emission 
of electrons under tbe influence of light- or RÖNTGEN rays. 
In the thermodynamical applications it appears to me that we 
may expect from the quanta-hypothesis, that it will yield results 
which are sometimes quantitatively and always qualitatively accurate. 
For it has the tendency to lower the kinetic energy of vibrators of 
short period in agreement with the observations to an amount 
smaller than would agree with the equipartition law. And it is only 
this mean energy which is observed in thermodynamics, or the 
distribution in space which is closely connected with it. 
Whether on the other hand the application of the quanta-hypo- 
thesis on the emission of electrons is justified seems doubtful to me. 
From a theoretical point of view it appears to me that no reason for 
the accuracy of the considerations can be found. And whether the 
agreement with experiment is sufficient to warrant the validity of 
the considerations seems to me to be still doubtful. 
If in particular we take the theory of SOMMERFELD for these pheno- 
mena with the aid of the quanta of “action”, then it appears to me 
that this theory (though perhaps accurate in itself) ean be in no 
way connected with any possible theory for the normal spectrum. 
Let us imagine e.g. two equal guns with equal projectiles but with 
unequal charges of gunpowder. The projectile with the greatest gun- 
powder charge will obtain the greater kinetic energy and that in 
the smaller time. And so we can assume that the molecular action 
is of such a nature that always the greater change of energy requires 
the shorter time in the way as is assumed by SOMMERFELD. This is 
a question of the law of action of molecular forces; it has nothing 
to do with the laws of mechanics, and in particular it is not con- 
tradictory to the laws of classical mechanics. I at last cannot discover 
any contradiction. But if indeed the theory of SOMMERFELD can be 
reconciled with classical mechanics then it can also be reconciled 
with the spectral formula of Rarrricn and leads by no means to 
the spectral formula of PLANCK. 
function ¢ must depend besides on the p's and the q’s also on the “proper 
coordinates” and that we, in connection with this, must add the differentials of 
the proper coordinates to the product of the differentials dp, ...dq,. 
