112 THE BEASON WHY. 



1 Let your light so shine before men, that they may see your good works, and 

 glorify your father which is in heaven." MATT. y. 



473. If a ray of light falls in a straight line upon a trans- 

 parent surface, is it then refracted ? 



In that case the ray pursues its course there is no refraction. 



474. Is the direction in which the rays are lent, or re- 

 fracted, influenced by the relative densities of the media '( 



A ray of light falling slantingly upon a window, in passing 

 through it is slightly brought to the perpendicular ; and if it then 

 falls upon the surfitce of water, it is still further brought to the 

 perpendicular in passing through the water. 



475. Is light refracted in passing from a dense medium to 

 a thinner one ? 



It is ; but the direction of the refraction is just the opposite to 

 the instance just given ; a ray of light passing through water into 

 air, does not take a more perpendicular course, but becomes more 

 oblique^ 



Fig. 11. 



476. Why, if a rod or a spoon be set in an empty lasin, 

 will it appear straight, or of its usual shape ? 



Because the rays of light that are reflected from it all pass through 

 the same medium, the air. 



477. Why if water be poured into the lasin will the rod ot 

 spoon appear lent ? 



Because the rays of light that pass through the water are 

 reflected in a different degree to those that pass through the 

 air. 





