94 REFLECTED AND TRANSMITTED LIGHT. 



than it is within the room, those in the room can see what 

 is passing in the street very well, while those in the street 

 can not see distinctly what is passing in the room. In the 

 evening, however, the case is reversed. Then, the room 

 being better lighted than the street, we have always to 

 close the curtains, for otherwise, the light being greater 

 now within than without, those who are within can not see 

 easily the objects without, while those without can see 

 very plainly what is passing within. 



This principle, simple as it is, operates in a thousand dif- 

 ferent ways, and intelligent young persons, who once un- 

 derstand it. will take pleasure in discovering examples of 

 it which will be continually coming under their observa- 

 tion, if they have only learned " how to observe." 



It is often, for example, well illustrated in the case of 

 water. "Water is transparent, and the surface of it, when 

 left in repose, makes plane and polishes itself, thus forming 

 a mirror; so that we can see objects on the bottom by 

 light which comes up through it, or objects on the banks 



BEFLKCT10N FRC 



