lo "N RAYS 



sought to concentrate the rays by means of a 

 quartz lens. The experiment is unattended 

 with difficulty. An image of the anticathode 

 is obtained, extremely well-defined as to size 

 and distance by a heightened glow of the small 

 spark. 



The existence of refraction rendered that of 

 regular reflection extremely probable ; as a 

 matter of fact, regular reflection does take 

 place. By means of a quartz lens, or a lens 

 formed by a very thin horn envelope filled with 

 turpentine, I produce a conjugate focus of the 

 anticathode ; then I intercept the emerging 

 pencil by a sheet of polished glass, placed 

 obliquely ; I then obtain a focus exactly sym- 

 metrical, in respect to the plane of reflection, 

 with the one which existed before the glass 

 was interposed. With a plate of ground glass 

 there is no regular reflection, but diffusion is 

 observed. 



If one half of a lamina of mica is roughened, 

 the polished half lets pass the radiations, and 

 the other half stops them (note 3). 



This allows of the repetition of the refrac- 

 tion experiments under much more precise 



