26 " N " RA YS 



between the shutter and the tube several sheets 

 of aluminium, cardboard, or an oak board 

 3 cms. thick, does not hinder the phenomenon ; 

 any possibility of an action of radiated heat, as 

 such, is consequently excluded. A thin film of 

 water completely arrests the rays ; light clouds 

 passing over the sun considerably diminish 

 their action. 



The " N " rays emitted by the sun can be 

 concentrated by a quartz lens ; by means of 

 the phosphorescent substance, the existence of 

 several foci is ascertained. I have not yet 

 determined their positions with sufficient pre- 

 cision to speak of them here. The " N " rays 

 of sunlight undergo regular reflection by a 

 polished plate of glass, and are diffused by 

 ground glass. 



The " N " rays issuing from the sun in- 

 crease the glow of a small spark and a small 

 flame in the same manner as those emitted by 

 a Crookes' tube, by a flame, or by an incan- 

 descent body. These phenomena are easy to 

 observe, especially if use is made of an inter- 

 posed sheet of ground glass, as indicated by me 

 in a preceding communication. The use of a 



