. 76 Inquiry concerning the Nature of Heat, 



Observed Temperature. Temperature 



Times when the obser- No. 3, No! 4, of the air of 



vations were made. naked. covered. the room. 



At 8h. 30111. . . 54! . 56 ... 



8 45 55i 57i 



9 ... 56i 5H ... 

 9 3 57* 60 



10 ... . 58^ . . 6i| . ... 



10 30 . 5 9 . 6z 



11 . . . . 6o . 63 ... 



II 30 . 6l 6 3a . 64^ 



The results of this experiment, and of several others 

 similar to it, showed, in a manner which appeared to 

 me to be perfectly conclusive, that those substances 

 which part with heat with the greatest facility, or celer- 

 ity, are those which also acquire it most readily, or with 

 the greatest celerity. 



If we might suppose that the temperatures of bodies 

 are changed, not by the rays they emit, but by those 

 they receive from other neighbouring bodies, this fact 

 might easily be explained ; but, without stopping to 

 form any hypothesis for the explanation of these appear- 

 ances, I shall proceed in my account of the various 

 attempts I have made to elucidate, by new experiments, 

 those parts of this interesting subject which still ap- 

 peared to be enveloped in obscurity. 



As the cooling of hot bodies is so much accelerated 

 by covering their surfaces with such substances as emit 

 calorific rays in great abundance, or with such as are 

 much affected by the frigorific rays of the colder bodies 

 by which they are surrounded, it seems to be highly 

 probable that a comparatively small part of the heat 

 which a body so cooled actually loses is acquired by 

 the air; a much greater proportion of it passing off 

 through that transparent fluid, under the form of calo- 

 rific rays, without affecting its temperature. 



