Mr. Powell on Light and Heat, ^-c, 45 



Art. VI.— 0;i Light and Heat from Terrestrial Sources, 

 By Baden Powell, M.A., F.R.S. 



[Communicated by the Author.] 

 To the Editor of the Quarterly Journal of Sciunce, S^c. 



Dear Sir, 



Your readers will be aware from the reports of the 

 proceedings of the Royal Society, that, on the 17th of February 

 last, a communication from me was read on the subject of radiant 

 heat ; having been for some time engaged in the inquiry into the 

 nature of the effects produced by the radiation from luminous hot 

 bodies^ as distinguished from that emanating from non-luminous 

 sources, I have made many other investigations besides those con- 

 tained in the paper alluded to. Some of these, comprised in the 

 following remarks, may be considered as supplementary to the 

 primary inquiry made in that paper ; and they lead to a very 

 simple theory of a subject which has hitherto been much involved 

 in confusion. Should you favour me by inserting them in your 

 Journal, I trust they may not be altogether uninteresting to your 

 readers ; especially as some of them are connected with topics 

 which have formed the subject of some of your own experiments. 

 I remain, dear Sir, 



Yours, very truly, 



Baden Powell. 



My whole inquiry is grounded upon the following assumptions, 

 which, I conceive, are warranted by the most decisive experiments 

 of Leslie, De la Roche, ^c. 



1. That simple radiant heat from non-luminous sources, pro- 

 duces its effect on bodies exposed to its influence in proportion to 

 a certain peculiarity of texture in their surfaces, which is the same 

 as that which gives them a greater power of radiating heat, and 

 is altogether independent of colour. 



2. That simple radiant heat is incapable of permeating glass 



