AN INQUIRY 



CONCERNING 



THE WEIGHT ASCRIBED TO HEAT. 



THE various experiments which have hitherto been 

 made with a view to determine the question, so 

 long agitated, relative to the weight which has been 

 supposed to be gained, or to be lost, by bodies upon 

 their being heated, are of a nature so very delicate, and 

 are liable to so many errors, not only on account of the 

 imperfections of the instruments made use of, but also 

 of those, much more difficult to appreciate, arising from 

 the vertical currents in the atmosphere, caused by the 

 hot or the cold body which is placed in the balance, 

 that it is not at all surprising that opinions have been 

 so much divided, relative to a fact so very difficult to 

 ascertain. 



It is a considerable time since I first began to medi- 

 tate upon this subject, and I have made many experi- 

 ments with a view to its investigation ; and in these 

 experiments I have taken all those precautions to avoid 

 errors which a knowledge of the various sources of 

 them, and an earnest desire to determine a fact which I 

 conceived to be of importance to be known, could in- 

 spire ; but though all my researches tended to convince 

 me more and more that a body acquires no additional 

 weight upon being heated, or, rather, that heat has no 

 effect whatever upon the weights of bodies, I have been 



