REFLECTING SURFACES. 89 



Almost all substances reflect a greater or less portion of 

 the light that falls upon them. When a substance does 

 not reflect light at all, it appears black. When the surface 

 is very smooth as smooth as it is when we say it is pol- 

 ished, and is at the same time plane then it reflects the 

 light regularly and uniformly, and we have an image of 

 the luminous source in it. This is because a sufficient num- 

 ber of the rays are simply turned from their coui-se and di- 

 rected toward the eye to form vision. They move at the 

 same angle, in relation to each other, after they are reflect- 

 ed as before, and so enter the eye just as they would have 

 done had they not been reflected, but only came from a dif- 

 ferent direction. 



But when, on the other hand, the surface is not polished, 

 then the portions of the surface on which the light falls 

 are broken and irregular; for, even though we call it 

 smooth, it is not perfectly smooth, and the different por- 

 tions of it reflect the light each in its own way. Thus the 

 light comes to our eyes in a confused manner. 



You can get a clear idea of this by first supposing that 

 a looking-glass is lying in the bottom of a basket, whole, 

 so as to reflect clearly and distinctly objects seen in it, and 

 then that afterward it is broken into pieces, and the pieces 

 lie in confusion in the basket, all, however, right side up. 

 The reflections would, in this last case, be confused. You 

 would see a general light, but no distinct image. 



This is precisely what happens in the case of ice. When 

 it is whole, and has a smooth and level surface, it reflects 

 the ice like a mirror; but when it is broken up into fine 

 pieces, it presents a general white appearance, like snow, 

 and that is all. Snow itself consists in minute sheets and 

 needles of ice, any one of which, by itself, reflects light like 

 a mirror ; but it is too small to reflect any complete object, 

 however minute, and so all the reflections coming conr 



