PECULIARITIES OF ACTION OF "N RAYS 73 



in all " N " ray experiments, that only the 

 observer placed exactly in front of the sensitive 

 screen perceives the effect of these rays. It also 

 shows how illusory it would be to try to make 

 an audience witness these experiments : the 

 effects perceived by different persons, depending 

 as they do on their positions with regard to the 

 screen, would certainly be contradictory or im- 

 perceptible. The rays I have called NI rays 

 have an inverse action in all cases to that of 

 " N " rays ; they diminish the light emitted 

 normally, and increase the light emitted tan- 

 gentially. M. Mace de Lepinay (see C. R. t. 

 cxxxviii. p. 77, January 1 1, 1902) has found that 

 sound vibrations increase the glow of a phos- 

 phorescent screen as seen by an observer view- 

 ing it normally. I have noticed that if the 

 screen is viewed tangentially, the phosphor- 

 escence is seen to decrease under the action of 

 the sound-waves. The action of a magnetic 

 field or of an electromotive force on a feebly 

 luminous surface, discovered by M. C. Gutton 

 (see C. R. t. cxxxviii. p. 268, February i, 

 1904), presents the same particularities. 



To sum up, in all the above-mentioned 



