TENDENCIES OF MODERN PHYSICS 43 



instance of this, he states that many of the most im- 

 portant discoveries in light were made when the er- 

 roneous corpuscular theory was still in vogue. But 

 does it necessarily follow that the theory prompted 

 the discoveries or led to their investigation because 

 they happened to be contemporaneous? It is difficult 

 to believe Bradley would have failed to obtain the 

 relation between the aberration of light and its finite 

 velocity if some other theory had been popular. Cer- 

 tainly the specific attributes assigned to light corpuscles 

 would have little influence in promoting such discover- 

 ies, since it was the habit to modify these without much 

 compunction if they did not square with observation. 

 And we are supported in this opinion by Professor 

 Larmor himself when he says : " At the same time all 

 that is known (or perhaps need to be known) of the 

 ether itself may be formulated as a scheme of differen- 

 tial equations, . . . which it would be gratuitous to 

 further explain by any complications of structure"; 

 and again : " The ultimate inadequacy of a method of 

 treating material media, based on merely empirical or 

 speculative additions to the ascertained equations of 

 free ether, had indeed been clearly recognized by von 

 Helmholtz." 



The questions, then, to be borne in mind while dis- 

 cussing these modern theories, are whether they involve 

 speculative additions to our equations and explanations 

 by complicated constructions, and whether they are 



