32 PRESENT-DAY RATIONALISM 



" One, however, must not infer that this represents 

 knowledge of a demonstrated kind, for it does not." 

 Yet Prof. Dolbear finally observes : " It is either that 

 theory or nothing. There is no other that has any 

 degree of probability at all." ^ Though Prof. Dolbear here 

 writes somewhat decidedly, one must add that it is not all 

 physicists who accept the theory of atomic vortex-rings. 

 Writing to Lord Kelvin to ask him how far, if at all, the 

 discoveries about radium affected the theory, he has been 

 so good as to reply as follows : " In answer to your letter, 

 radium has nothing to do with vortex-rings. About 

 1886 I utterly abandoned the idea that atoms of matter 

 could be vortex-rings ; or that the theory of vortex-rings 

 (a beautiful and admirable result of mathematical work in 

 the dynamics of an ideal perfect liquid) could contribute 

 anything towards an explanation of the atoms of matter 

 and their mutual actions. I had occupied myself much 

 with that idea for about twenty years ; but I abandoned 

 it when I became convinced that there was no truth or 

 help towards truth in it." 



Since the above was published, Prof. O. Reynolds, 

 F.R.S., has delivered the Rede lecture at Cambridge, 

 and broached a new theory in it, that ether consists of in- 

 conceivably small grains. Matter represents a deficiency 

 of these grains [how were they lost ?] causing a strain in 

 the medium and thus accounting for the law of gravita- 

 tion, etc. 



Experts only can determine what degree of proba- 

 bility Prof. Reynolds's theory may have to support it ; 

 or how far it interferes with that of vortcx-rings. At all 

 events, at a later date (ist May, 1903) Lord Kelvin 

 had occasion to say that he was " horrified to read in the 



1 Matter, Ether and Motion (S. P. C. K., 1899). 



