PURE AND REFLECTED LIGIIT 
3 
lost to us in the upper air, and that which 
finally comes on down to the earth has to our 
eyes a prevailing whitish, reddish, or yellow 
tone, dependent upon the density of the air. If 
we could sweep away our atmosphere entirely, 
the light would appear bluish and the sun itself 
violet-blue.* There is a predominance of vio- 
let and blue in sunlight, but the waves of these 
colors being the shortest and weakest in travel- 
ling power, are the first ones to be caught and 
absorbed by the upper atmosphere. Held in 
check, entangled as it were, quantities of them 
are massed above us, making what we call “the 
blue sky.” The yellow and red waves, having 
greater length and power than the blue ones, 
penetrate the atmosphere deeper and come to 
us with the tale that the sun is yellow or red 
or, in combination with other colors, white. 
But the tale is deceptive. Sunlight in its 
entirety appears whiter and then bluer, in pro- 
portion as we rid ourselves of our atmospheric 
lens; and the sky itself grows darker from the 
non-diffusion of the sun’s rays. An ordinary 
rain-storm that clears the atmosphere will tem- 
* This is the conclusion of Professors Langley, Young, 
and other scientists. If seen from a distant world, our 
sun would appear as one of the blue stars. 
Violet-blue 
sunlight. 
