(49) * 6 3 



by the same pebble might be infinitesimal. Now we 

 have already made it clear to our minds that to preserve 

 the solar light white, its constituent proportions must 

 not be altered ; but in the act of division performed by 

 these very small particles we see that the proportions 

 are altered ; an undue fraction of the smaller waves is 

 scattered by the particles, and, as a consequence, in the 

 scattered light blue will be the predominant color. The 

 other colors of the spectrum must, to some extent, be 

 associated with the blue. They are not absent, but de- 

 ficient. We ought, in fact, to have them all, but in dimin- 

 ishing proportions, from the violet to the red. 



We have here presented a case to the imagination, 

 and assuming the undulatory theory to be a reality, we 

 have, I think, fairly reasoned our way to the conclusion 

 that, were particles, small in comparison to the size of 

 the ether waves, sown in our atmosphere, the light scat- 

 tered by those particles would be exactly such as we ob- 

 serve in our azure skies. When this light is analyzed 

 all the colors of the spectrum are found ; but they are 

 found in the proportions indicated by our conclusion. 



Let us now turn our attention to the light which passes 

 unscattered among the particles. How must it be finally 

 affected ? By its successive collisions with the particles, 

 the white light is more and more robbed of its shorter 

 waves ; it therefore loses more and more of its due pro- 

 portion of blue. The result may be anticipated. The 

 transmitted light, where short distances are involved, 

 will appear yellowish. But as the sun sinks towards the 

 horizon, the atmospheric distances increase, and con^ 

 sequently the number of the scattering particles, They 

 abstract, in succession, the violet, the indigo, the blue, 

 and even disturb the proportions of green. The trans- 



