on the terrestrial Rays that occasion Heat. 527 



ciency of 242 rays, we now have an excess of 1 13 ; which plainly 

 shews, that no hypothesis of any other proportion between the 

 visible and invisible rays of heat can answer to both cases ; and 

 that consequently, not only the present, but every other assump- 

 tion of this kind, must be given up as erroneous. 



I shall not enlarge on these arguments, as I take them to be 

 sufficiently clear to decide the question we have had under con- 

 sideration. I also forbear going into an examination of what our 

 sixth article, which treats of scattered heat, might afford, in ad- 

 dition to the former arguments. It may just be remarked, that 

 the 211th experiment points out a black object, which scatters 

 more heat than a white one ; while the case, as to light, is well 

 known to be the reverse. The 219th experiment also shews, 

 that the scattering of heat of gold paper is considerably inferior 

 to that of black velvet ; whereas a contrary difference, of a very 

 great extent, is pointed out between these two substances ; for 

 black velvet scatters only 7 rays of light, while the scattering 

 of gold paper amounts to more than 1 24000. I am well aware 

 that this difference will perhaps admit of a solution on other 

 principles than those which relate merely to the laws of scat- 

 tering, and confess that many experiments are still wanting to 

 complete this article, which cannot now be given ; but, as this 

 Paper is already of an unusual length, I ought rather to apolo- 

 gize for having given so much, than for not giving more. 



3Y2 



