Experiments with Rontgen! s Rays* 



459 



per second, so that the conclusion to be drawn from the 

 experiment is that the Rontgen radiation is not associated 

 with aether velocities greater than, say, one fifth of a kilo- 

 metre per second, or about a thousand times less than that 

 of kathode rays as measured in a vacuons tube by Prof. J. J. 

 Thomson (Phil. Mag. vol. xxxviii. p. 364). 



Experiment to test whether Rontgen Rays produce any change 

 in aether affecting the velocity of light. 



An experiment (fig. 3) was arranged on Michelson's 



Fig-. 3. 



(K-Sh** I* 



principles. In this case the sodium light from L is divided 

 at the partially silvered mirror A, one beam travelling to C 

 and thence to T, the other travelling to B and thence back to 

 T. The path AC is operated upon by the tube, and the path 

 AB is screened by a heavy cast-iron screen. The active 



