314 A. A. Michelson— Theory of the " X-BaysP 



The production of fluorescence, actinic effects, and the dissi- 

 pation of electric charges by light (which is an ether motion) 

 would make it at least probable that similar (though perhaps 

 not identical) effects would be produced by the motions of 

 ether-vortices. 



Professor J". J. Thomson has measured the velocity of 

 cathode-rays and obtained a result so very far less than the 

 velocity of light as to preclude entirely the idea of there being 

 any connection between the two. If these results can be made 

 to apply to the X-rays, the analogy with the properties of 

 smoke-rings would lead us to expect such a result. The 

 cathode rays have been shown by Lenard to have a considera- 

 ble range in their properties, depending on the mode of their 

 origin.* It seems likely that their velocities are to a consid- 

 erable extent dependent on the potential and the suddenness of 

 the electrical impulse ; and if this were shown to be true of the 

 X-rays, it would be to that extent a confirmation of the theory. 



The foregoing evidence may be considered scarcely suffi- 

 cient to entitle the proposition here advocated to the dignity 

 of a theory, but it may at least merit consideration as a 

 working hypothesis which may serve as a guide in future 

 experiment. 



* The distinction between the X-rays and the cathode rays appears to be 

 somewhat artificial, and it seems probable that the X-rays are only cathode rays 

 sifted by the various media they have traversed. 



