SCIENTIFIC MEMOIRS. 



MEMOIK I. 



EXAMINATION OF THE RADIATIONS OF RED-HOT BODIES. 

 THE PRODUCTION OF LIGHT BY HEAT. 



From the American Journal of Science and Arts, Second Series, Vol. IV., 1847; 

 London, Edinburgh, and Dublin Philosophical Magazine, May, 1847 ; Harper's 

 New Monthly Magazine, No. 322. 



CONTENTS : Ascertainment of the temperature at which bodies become 

 self-luminous; it is 977 Fahr. Proof that all solids begin to shine 

 at the same degree. The spectrum of incandescent solids has no fixed 

 lines. The reference spectrum. Colors of light emitted as the heat 

 increases are in the order of the spectrum. Frequency of vibration 

 increases with the temperature. Intensity of the light emitted. In- 

 tensity of the heat radiated. 



ALTHOUGH the phenomenon of the production of light 

 by all solid bodies, when their temperature is raised to 

 a certain degree, is one of the most familiar, no person 

 so far as I know has hitherto attempted a critical in- 

 vestigation of it. The difficulties environing the inquiry 

 are so great that even among the most eminent philoso- 

 phers a diversity of opinion has prevailed respecting 

 some of the leading facts. Thus Sir Isaac Newton fixed 



O 



the temperature at which bodies become self-luminous 

 as 635; Sir Humphrey Davy at 812; Mr. Wedgwood 

 at 947; and Mr. Daniel at 980. As respects the nature 

 of the licrht emitted, there are similar contradictions. In 



O 



some philosophical works of considerable repute it is 



