144 Experimental Investigations 



The science of heat is not only of great curiosity, from 

 the multitude of astonishing phenomena it offers to our 

 contemplation, but it is likewise extremely interesting 

 from its intimate connection with all the useful arts, and 

 generally with all the mechanical occupations of human 

 life. 



Without a knowledge of heat, it is not possible either 

 to excite it with economy or to direct its different opera- 

 tions with facility and precision. 



SECTION III. Experiments tending to show that Heat is 

 communicated through solid Bodies, by a Law which 

 is the same as that which would ensue from Radiation 

 between the Particles. 



Having made a considerable number of experiments 

 on the passage of heat through fluids, and through dif- 

 ferent substances in the state of powder, I was curious 

 to ascertain the laws of its propagation through solid 

 bodies, particularly metals. 



I hoped this discovery would furnish some additional 

 data to confirm or refute the opinions I had adopted 

 concerning heat and its manner of acting ; and it will 

 be seen by the results that my expectations were not 

 frustrated. 



Having procured two cylindrical vessels of tin, each 

 six inches in diameter and six inches high, I fastened 

 them together, by means of a solid cylinder of copper, 

 six inches long and an inch and a half in diameter, 

 which was fixed horizontally between the two tin ves- 

 sels. The extremities of the cylinder passed through 

 two holes, an inch and a half in diameter, made for 

 the purpose in the sides of the vessels, midway be- 



