From Newton to Kirchoff. By Lerot C. Cooley, Ph. D. 



[Read before the Albany Institute, April 16, 1872,] 



Two centuries past this very year, Sir Isaac Newton un- 

 bound a beam of sunlight and spread its wealth of colors 

 upon a screen. There was red and orange and yellow; 

 there were green, blue, indigo and violet unsurpassed in 

 purity and beauty by those of the most brilliant rainbow 

 or of the rarest flowers. As science then stood, the great 

 philosopher was content to receive the honor due to one 

 who had made a wonderful discovery in optics, but the 

 light thrown back upon it by the science of to-day shows 

 his discovery to have been one of the most important steps 

 ever taken in the progress of astronomy. The Copernican 

 theory, two hundred years before, had opened the way for 

 wonderful applications of mathematics by which a know- 

 ledge of sizes, distances and motions of celestial bodies 

 was evolved; the discovery of the solar spectrum made 

 possible the splendid revelations of modern chemistry con- 

 cerning the composition and structure of these distant bodies. 



Compressed within the small space covered by a solar 

 spectrum is the beautiful language in which the chemistry 

 of the heavens is written ; but, wrapt in colors richer than 

 are ever elsewhere beheld, Sir Isaac did not see it, and for 

 more than a century afterward no eye detected its delicate 

 characters. 



In the year 1815, a German optician, by the name of 

 Fraunhofer, conceived the happy thought of repeating 

 Newton's experiment, changing only the form of the sun- 

 beam. , Instead of a circular opening to admit the beam 



