68 Mr. James Bice on 



sum of an enormous number of simi>le vibrations, each one of 



which corresponds to one degree of freedom of this A^ohime of 



ether. Owing to the uncontrolled motions of the molecules of 



the walls and their internal parts, the motion of the ether is just 



as uncontrolled. The actual state of one tiny })ortion of it at a 



defined instant is as unpredictable as that of a single molecule, 



but the energy of the whole should be given by the principle of 



equipartition, i.e., for every degree of freedom there should be 



energy of radiation always present of amount 



2 



^- a T ergs 



where T is the temperature of the enclosure, - a T ergs being 



the average kinetic energy per degree of freedom and - a T being 



o 



the average potential energy. Now, as I have stated above, the 



number of degrees of freedom, or simple types of vibration 



possible for the ether in the enclosure is first of all proportional 



to the volume, as one would expect, and then to the cube of the 



highest frequency possible. The question naturally arises — is 



there any highest frequency 1 If the ether is to be regarded as 



an absolutely continuous medium, there is not ; and this leads to 



the conclusion that the number of degrees of freedom of the 



ether is genuinely infinite, not merely enormously large like that 



of the walls of the enclosure ; and this means that in the steady 



state corresponding to a definite temperature while there would 



be a finite amount of energy in the walls, there would be an 



infinite amount in the enclosed ether, a statement which really 



means that the only possible steady condition would be one in 



which all the energy would be in the ether and none in the 



walls, which would therefore be at absolute zero. 



But let us waive this difficulty ; yet we are not freed from 



anomalies. Let us put an upper limit to the types of vibration 



which the ether may have. Experiment has shewn that the 



ether, even if it has a structure, is nothing like as coarse-grained 



