EFFECT OF REFRACTION. 



195 



POLE 8EEMLNG TO BE BENT. 



to us in the place from which the rays seem to come when 

 they enter the eye. 



This refracting effect upon rays passing in an oblique 

 direction into or out of surfaces of water or glass has long 

 been known. Indeed, it gives rise to phenomena which 

 are to be observed all around us every day. Newton, 

 however, in his investigations, ascertained that the light 

 thus bent out of its course was, in some mysterious way, 

 separated in the bending into different component parts. 



The engraving on the following page represents this 

 phenomenon in its simplest form. A beam of light from 

 the sun enters through an orifice (a) made in the shutter 

 into a darkened room ; for, though this is not essential, the 

 effect is far more decided when all other light except the 

 beam to be experimented upon is excluded. The ray, in 

 entering from the air into the prism (shown in section in 

 the engraving) at #, is refracted upward, and slightly sep- 



