i6o CLASSICS OF MODERN SCIENCE 



this point, which I have described at length in my memoir in the 

 Philosophical Transactions, are more than sufficient to establish this 

 fact beyond doubt. 



Just as little does it come from a change in the capacity for heat 

 brought about by friction in the metal of which the hemispheres are 

 composed. This is shown, first, by the continuance and uniformity of 

 the production of the heat ; and, secondly, by an experiment bearing 

 directly on this point, by which I am convinced that not the slightest 

 change had taken place in the capacity of the metal for heat. 



Just as little does it come from the rods which are attached to the 

 hemispheres, for these rods were always warm, the hemispheres com- 

 municating heat to them. 



Much less could this heat come from the air of the water imme- 

 diately surrounding the hemispheres, for the apparatus communicated 

 heat to both these fluids without cessation. 



Whence, then, came this heat ? and what is heat actually ? 



I must confess that it has always been impossible for me to explain 

 the results of such experiments except by taking refuge in the very 

 old doctrine which rests on the supposition that heat is nothing but a 

 vibratory motion taking place among the particles of bodies. 



A bell, on being struck, immediately gives forth a sound, and the 

 oscillations of the air produced by these vibrations forthwith cause a 

 quivering motion in those bodies with which they come in contact. 

 On the other hand, a sponge filled with water cannot give off its mois- 

 ture to the bodies in its vicinity for any length of time without itself 

 losing moisture. 



A very illustrious philosopher, for whom I have always enter- 

 tained the greatest respect, and whom, moreover, I have the good for- 

 tune to count among my most intimate friends, M, Bertholet, has, in 

 his admirable Essai de Statique Chimique, attempted to explain the re- 

 sults of this investigation, and to reconcile them with that theory of 

 heat which is founded upon the hypothesis of caloric. 



If a man as learned, as honest, as worthy, and as renowned as is 

 M. Bertholet spares no pains in opposing the errors of a natural phi- 

 losopher or chemist, one cannot and dare not keep silence unless he 

 wishes to acknowledge himself vanquished. If, however, one can 

 produce proofs — a fortunate thing for all those who find themselves 

 driven to similar self -vindication — that the objections of M. Bertholet 



