SOME UNSOLVED SCIENTIFIC PROBLEMS 



based on the supposition that the ether is not quite 

 f rictionless ; Professor Dolbear's suggestions as to the 

 creation of matter through the development of new 

 ether ripples, and the same thinker's speculations as 

 to an upper limit of temperature, based on the mechan- 

 ical conception of a limit to the possible vibrations of a 

 vortex ring, not to mention other more or less fascinat- 

 ing speculations based on the vortex hypothesis, must 

 be regarded, whatever their intrinsic interest, as in- 

 securely grounded, until such time as new experimental 

 methods shall give them another footing. Lord Kel- 

 vin himself holds all such speculations utterly in abey- 

 ance. " The vortex theory," he says, " is only a dream. 

 Itself unproven, it can prove nothing, and any specu- 

 lations founded upon it are mere dreams about a 

 dream." * 



That certainly must be considered an unduly modest 

 pronouncement regarding the only workable hypothe- 

 sis of the constitution of matter that has ever been 

 imagined ; yet the fact certainly holds that the vortex 

 theory, the great contribution of the nineteenth century 

 towards the solution of a world-old problem, has not 

 been carried beyond the stage of hypothesis, and must be 

 passed on, with its burden of interesting corollaries, to 

 another generation for the experimental evidence that 

 will lead to its acceptance or its refutation. Our cen- 

 tury has given experimental proof of the existence of 

 the atom, but has not been able to fathom in the same 

 way the exact form or nature of this ultimate particle 

 of matter. 



Equally in the dark are we as to the explanation of 

 that strange affinity for its neighbors which every atom 



217 



