A KINETIC THEORY OF MATTER. 251 



the model vortex gas composed of perforated 

 solids with fluid circulations through them holds 

 without modification for the purely hydrokinetic 

 model, composed of either Helmholtz cored 

 vortex rings or of coreless vortices, and we are 

 now troubled with no such difficulty as that of 

 the impacts between solids. Whether, however, 

 when the vortex theory of gases is thoroughly 

 worked out, it will or will not be found to fail 

 in a manner analogous to the failure which I have 

 already pointed out in connection with the 

 kinetic theory of gases composed of little elastic 

 solid molecules, I cannot at present undertake 

 to speak with certainty. It seems to me most 

 probable that the vortex theory cannot fail 

 in any such way, because all I have been able 

 to find out hitherto regarding the vibration of 

 vortices, 1 whether cored or coreless, does not 

 seem to imply the liability of translational or 



1 See papers by the author " On Vortex Motion," Trans. J?. S. E.> 

 April, 1867, and " Vortex Statics," Proc. R. S. ., December, 1875 ; 

 also a paper by J. J. Thomson, B.A., "On the Vibrations of a 

 Vortex Ring," Trans. R. S. t December, 1881, and his valuable book 

 On Vortex Motion (being the Adams prize essay for 1882). 



