COLORIFICATION IN GENERAL. 335 



the different colors, which different bodies situ- 

 ated in it, are found to display, by the clouds, 

 so diversified in appearance, by the electric 

 fire, as well as by different parts of the planetary 

 system. Who is there, that has not observed 

 the flery color of the rising and the setting sun, 

 and the pale and colorless appearance which it 

 assumes in the middle of a clear day? How is it 

 possible, with all these facts constantly before our 

 eyes, not to admit, that it is owing to the union 

 which has taken place between the solar rays 

 and the matter of the medium through which 

 they pass, that these colors are produced. No 

 proof, perhaps, is more strong, of the uniformi- 

 ty existing in the composition of the atmos- 

 pheric matter, by which the medium above is 

 filled, than the uniformity in the rays of color 

 which are formed by the passage of the rays of 

 light through it, and which are separated from 

 each other by means of the prism, and thence 

 called prismatic colors. It is for the purpose of 

 describing the different mechanical phenomena 

 which these different colors display, that the 

 science of optics is especially designed, the lead- 

 ing propositions of which are as follows. 



Def. 1. Light. (Color it ought to have been 

 called.) Light is that, which proceeding from 

 any body to the eye, produces the perception 

 of seeing. 2. A ray of color is an exceedingly 

 small portion of light (or matter) as it comes 



