NATURE FOR ITS OWN SAKE 



Atmospher- 

 ic obstruc- 

 tions. 



Particles in 

 the air. 



We have, perhaps, a contempt for the knowl- 

 edge of light possessed by the inhabitants of 

 the deep, but our contempt is somewhat shal- 

 low. For we ourselves are living at the bottom 

 of an even greater sea the vast atmospheric 

 ocean. We are looking up to the light through 

 countless strata of air that break and twist and 

 shatter the sunbeam looking up not through 

 five hundred feet, but probably five hundred 

 miles of air- wave. Perhaps, were we brought up 

 and out of our sea and into the regions of space, 

 our eyes, too, might be blinded by the sharp shaft 

 of a pure and clear sunlight. Our knowledge of 

 it is only comparative, a step upward from that 

 of the fish. The truth in the superlative de- 

 gree will never be attained. Human eyes have 

 never seen pure sunlight, and that white light 

 which we regard as such is anything but pure. 

 It is not the sum of all radiation, as we are ac- 

 customed to think, but the residue, that which 

 remains after the passage through atmosphere. 



The air we breathe is filled with countless 

 particles of dust, smoke, soot, salt crystals, 

 vapor ; and these particles break light into 

 color by obstructing the beams, t The sun ray 

 is thus disintegrated as soon as it encounters 

 our outer atmosphere. Some of it is practically 



