19 



cold," and many other phenomena. Heat seems of late 

 nearly divorced f'-om light and color, though this is only 

 an ai)[)arcnt sepai-ation. The Actien theory materially 

 qualities the estimate of the nature and origin of all these 

 elements. Late astronomical publications still tell of 

 the heat of the body of the sun, and the hourly con- 

 sumption of combustible material on its surface necessary 

 for our supply of light and heat. But the present ad- 

 vanced undulatory theory of light promises to qualify 

 such a principle very much. 



The fact of increasing darkness and coldness, experi- 

 enced by one in rising from the mean surface of the earth, 

 either 1)\- climbinij mountains or balloon ascension, magf- 

 nities the doubt that heat is emitted from the sun in the 

 form received by us; and the result of investigation 

 plausibly shows that we may yet account for the origin 

 of the caloric that we use, in a much more satisfactory 

 and perhaps economical manner. 



The advocates of the spectroscopic theory base their 

 belief principally on the undulatory theory of light, which 

 the}' claim Sir Isaac Xewton denied, as well as upon the 

 theory that light is composed of colors, which he did, 

 emphatically, deny ; and as the correctness of the spec- 

 troscopic theory in a measure depends on this misconcep- 

 tion of the real constituents of white light, it seems 

 properly a subject for investigation. Newton's theory 

 of white light, as generally understood, is an emission, or 

 corpuscular theory, and that its rays are a compound of 

 seven ditferent colors, made up of corpuscles ; thus con- 

 tradicting the theory of undulations. But from careful 

 investigations of his original Avork, which these assump- 

 tions render necessary, it will be found that his idea was 

 essentially different from that which has usually been at- 

 tributed to him, during the past fifty years. It not only 



