184 



earth and all the other planets chained to the sun by the 

 attractive power of its rays, but their motions are deter- 

 mined by its motion, and the physical forces which regulate 

 all cosmical phenomena, have their source within its 

 body. 



The sun is termed the fountain of light ; it is equally the 

 source of every other power with which science has made 

 us acquainted. 



Since the time when Newton analyzed the solar beam, 

 the advance of our knowledge has been most rapid. 



We are acquainted with luminous rays which had never 

 been seen by Newton ; and of actinism or the chemical 

 power of the sumbeam, he knew nothing. 



The beautiful phenomena of the polarization of light 

 were unknown to him, and he had not the most remote idea 

 of the existence of numerous dark lines crossing even the 

 most brilliant divisions of the Newtonian spectrum, and 

 which promise to advance our knowledge by the discovery 

 of many sublime truths. 



If we place a triangular prisum in the path of the sun- 

 beam, the rays are bent out of their course or refracted, 

 and by this means decomposed into a beautiful flamelike 

 chromatic image. Now if this solar spectrum be received 

 upon a screen, it will be found to consist of several colored 

 bands ; crimson, red and orange passing into yellow from the 

 least refracted end, while from the most refrangible one we 

 have lavender, violet, indigo blue and green also passing 

 into yellow as they advance to the true centre of the spectral 

 image. 



These rays constitute the Newtonian spectrum, thus call- 

 ed because Newton was the first to examine with precision 

 the relative condition of these colored bands, and to estab- 

 lish with any approach to correctness the laws regulating 

 the relations of color and refraction. Anno, 1675. 



Beyond the most refrangible end of this spectrum there 

 exists another class of rays, w T hich are not visible under 



