1835.] into the Composition of White Light. 33 



produce such experimental confirmation of the theoretical 

 views here advanced, as will, in my opinion, leave no doubt 

 on a question which, though it may not be considered of 

 any great importance, it is certainly desirable to settle. 



•53 



9 

 10 



In Fig. 1. the light which falls on the face of the prism 

 a c, is represented emerging from J c in three different direc- 

 tions, so as to become completely developed upon a screen 



VOL. II. D 



