THE BLUE SKY 



61 



landscape. Whence comes the light thrown 

 back to heaven by these objects if not from the 

 blue sky overhead ? Because sky-beams do not 

 fall like rain-drops we think, perhaps, they do 

 not fall at all ; but their presence in reflection 

 is abont ns on every hand. 



But possibly more beautiful than the trans- 

 mission of light is its reflection as shown upon 

 this same blue dome of air. When the sun is 

 in the zenith all the light is transmitted, but 

 when the sun is below the horizon its light is 

 thrown up and under the blue and is reflected. 

 Instead of looking into the shadows of air par- 

 tides we are looking into their high lights. 

 This gives the effect upon the eastern sky 

 that we call the dawn, and the more gorgeous 

 effect in the west, called twilight. These two 

 effects are the only ones that reveal fully the 

 reflecting power of the sky. If we could rise 

 above the earth and from the moon look out tow- 

 ard this world of ours, we should doubtless see it 

 muffled by a great luminous covering. The light 

 from it would all be reflected and the white, misty 

 air might completely hide the earth from view. 

 It would not, however, be a brilliant or scintil- 

 lant light. Like that of the dawn, it would be 

 softly pervasive. The atmosphere from which 



from tl* 



