72 "N RAYS 



N! rays can be stored up like " N " rays. 

 For instance, one need only bring a bit of 

 stretched copper wire in proximity to a lump of 

 quartz to make the quartz emit N! rays for 

 some time after. 



On Peculiarities presented by the Action 

 exercised by "A r " Rays on a Dimly 

 Lighted Surface (February 2, 1904). 



Consider a phosphorescent screen, or, more 

 generally, a dimly lighted surface. If this sur- 

 face is viewed normally, one notices that the 

 action of " N " rays is to render it more lumin- 

 ous ; if, on the contrary, the surface is viewed 

 very obliquely, nearly tangentially, the action 

 of " N " rays is to render it less luminous. In 

 other words, the action of " N " rays in- 

 creases the quantity of light normally emitted, 

 while it diminishes the light emitted in a 

 very oblique direction. If one looks at it in 

 an intermediate position, no appreciable effect 

 is observed. This explains the fact, observed 



