186 



NATURE FOB ITS OWN SAKE 



We are looking down upon the bush and see 

 sunlight upon its green leaves ; but the reflec- 

 tion shows us that under-portion of the bush 

 which is in shadow. 



The rule governing our perception of reflec- 

 tions is a familiar one : The angle of reflection 

 is always equal to the angle of incidence. Prac- 

 tically applied to our illustration, this means 

 that standing twenty feet above the bush and 

 fifty feet back from it, we see in reflection just 

 what we should see in the original did we stand 

 twenty feet below the bush and fifty feet back 

 from it. Again, if standing twenty feet above 

 the surface we can see a portion of a mountain- 

 peak reflected in the water, then we could see 

 just that much of the peak itself if twenty feet 

 below the surface. Every Swiss tourist has seen 

 Mt. Blanc mirrored in the Lake of Geneva, 

 though the two are some forty miles apart. 

 The reason is that Mt. Blanc is some three miles 

 high. By increasing our height we see less of 

 the reflection in proportion, as by increasing 

 our depth we see less of the original. At the 

 bottom of a well, looking up, we should be able 

 to see only the sides of the well and the sky ; if 

 at the top of the well, looking down, we should 

 see the same things in reflection. 



