THE ETHER AND GRAVITATION 



those of light ; or, as Hertz modestly stated : " It seems 

 to me that the above described experiments must 

 serve to a great degree to remove all doubt as to the 

 identity of light, radiant heat and electro-dynamical 

 wave movements." They also prove the existence 

 of the Ether in which they have their being, what- 

 ever may be its constitution, beyond the possibility 

 of farther dispute. The radiant Magneto-Electric 

 waves are of great length and relatively very slow. 

 They are the source of the waves used in Wireless 

 Telegraphy. Many have thought that Gravitation 

 depended in some way on Electricity, but it is a 

 phenomenon of the Ether still unexplained. 



The Law of Parsimony in Philosophy should lead to 

 the acceptance of the atomic theory of the Ether as the 

 probable cause of gravitation ; at least, until a better 

 and more satisfactory solution of the problem can be 

 suggested. It is, moreover, the only theory that is 

 plausible, or even possible, so far as known. It 

 should be borne in mind that it was long after New- 

 ton's time that the difficulties in his theories of light 

 and of the laws of gravitation were reconciled ; that 

 the erroneous views that even he held were cor- 

 rected and the truth of his main laws established, and 

 it may so prove in this case. Thus the determination 

 of the problem, " What is Gravity ? " has not yet 

 received a generally accepted answer. That it is the 



