212 Notices respecting New Books. 



(f) Discussion of the Chemical Action of light and proof that 

 rays of all wave-lengths are capable of producing chemical changes. 



(g) Researches on the distribution of Heat in the Spectrum. 

 And, finally, an elaborate investigation, publishedin 1847, by which 



he established experimentally the following facts, which we will 

 give in the words of the Award : — 



" 1. All solid substances, and probably liquids, become incan- 

 descent at the same temperature. 



" 2. The thermometric point at which substances become red- 

 hot is about 977° Fahr. 



" 3. The spectrum of an incandescent solid is continuous ; it con- 

 tains neither bright nor dark fixed lines. 



" 4. From common temperatures nearly up to 977° Fahr. the 

 rays emitted by a solid are invisible. At that temperature they 

 are red ; and the heat of the incandescing body being made con- 

 tinuously to increase, other rays are added increasing in refrangi- 

 bility as the temperature rises. 



"5. "While the addition of rays, so much the more refrangible as 

 the temperature is higher, is taking place, there is an increase in 

 the intensity of those already existing." The Award then proceeds 

 as follows : — " Thirteen years afterwards Kirchhoff published his 

 celebrated memoir on the relations between the coefficients of 

 emission and absorption of bodies for light and heat, in which he 

 established mathematically the same facts and announced them as 

 new." 



"We are, of course, aware that this is rather a burning question ; 

 but whatever may be thought of the justice of these claims, there 

 can be no doubt that the fact of their having been made on behalf 

 of Dr. Draper by so distinguished a body as the American Academy 

 of Arts and Science ought to be known, and that its judgment 

 will receive at least respectful consideration whenever the early 

 history of Spectroscopic Science comes to be written. And it is 

 impossible not to draw attention to the fact in a notice, however 

 brief, of Dr. Draper's volume ; for plainly one of the motives of its 

 publication is to assert his claims to priority of discovery in re- 

 gard to the points above quoted. In fact the four memoirs which 

 bear directly on the subject of Spectrum Analysis are printed first 

 in the volume, and are followed by a note in which Dr. Draper 

 complains, though in very decorous language, that he has received 

 considerably less than justice at the hands of M. Kirchhoff ; and by 

 way of showing that he has tangible grounds for complaint, he makes 

 the following quotation (p. 85) from M. Jamin's Cours de Physique, 

 in which results that he had previously established are formally at- 

 tributed to M. Kirchhoff. 



" M. Kirchhoff has deduced the following important conse- 

 quences : — 



"Black bodies began to emit at 977° Fahr. red radiations, to 

 which are added successively and continuously other rays of in- 

 creasing refrangibility as the temperature rises. 



