36 "N" RAYS 



the exception of a vertical slit cut at the same 

 height as the Auer burner, and stopped up by 

 transparent paper, a flame was disposed so as 

 to light up the slit. By suitably placing the 

 eye and the slit, the image of this latter is seen 

 formed by reflection on the steel cylinder, and 

 simultaneously the reflecting surface is receiv- 

 ing the " N " rays. It was then easy to observe 

 that the action of these rays reinforces the 

 image, for if they are intercepted, the image 

 darkens, and turns to a reddish hue. I re- 

 peated this experiment with the same success 

 by employing, instead of the knitting-needle, a 

 plane mirror of bronze. 



The same result is again obtained by reflect- 

 ing the light on the polished face of a block of 

 quartz. However, when the " N " rays fall 

 normally on the refracting face, their action on 

 reflected light disappears, whatever be the 

 incidence of this light, whether it be that their 

 action becomes zero, or simply inappreciable. 

 In order that the light reflected by the quartz 

 may be reinforced by the " N " rays, it is not 

 necessary that the rays should be directed 

 towards the interior of the quartz ; the action 



