96 INTERFERENCE OF RADIATIONS. [MEMOIR V. 



culty than that of the ideal coloration of glass, a difficulty 

 arising from the magnitude of the ^refracting faces of the 

 prism. It is this which makes a prismatic spectrum 

 blacken paper, made sensitive with the bromide of silver, 

 from the red to the violet end; whereas the diffraction 

 spectrum shows that the true action is confined to the 

 more refrangible side, and stops short of the centre of 

 the yellow space. 



UNIVERSITY OF NEW YORK, Dec. 24, 1846. 



