474 Inquiry concernmg the Source of 



latent Heat of the metallic chips. But, not being wil- 

 ling to rest satisfied with these trials, however conclusive 

 they appeared to me to be, I had recourse to the follow- 

 ing still more decisive experiment. 



Taking a cannon (a brass six-pounder), cast solid, 

 and rough as it came from the foundry (see Fig. i. 

 Tab. IV.), and fixing it (horizontally) in the machine 

 used for boring, and at the same time finishing the out- 

 side of the cannon by turning (see Fig. 2), I caused 

 its extremity to be cut off, and, by turning down the 

 metal in that part, a solid cylinder was formed, yf inches 

 in diameter, and (^^-^ inches long, which, when finished, 

 remained joined to the rest of the metal (that which, 

 properly speaking, constituted the cannon) by a small 

 cylindrical neck, only i\ inches in diameter, and 1^^^ 

 inches long. 



This short cylinder, which was supported in its hori- 

 zontal position and turned round its axis by means of 

 the neck by which it remained united to the cannon, 

 was now bored with the horizontal borer used in boring 

 cannon ; but its bore, which was 3.7 inches in diameter, 

 instead of being continued through its whole length (9.8 

 inches) was only 7.2 inches in length ; so that a solid 

 bottom was left to this hollow cylinder, which bottom 

 was 2.6 inches in thickness. 



This cavity is represented by dotted lines in Fig. 2 ; 

 as also in Fig. 3, where the cylinder is represented on an 

 enlarged scale. 



This cylinder being designed for the express purpose 

 of generating Heat by friction^ by having a blunt borer 

 forced against its solid bottom at the same time that it 

 should be turned round its axis by the force of horses, 

 in order that the Heat accumulated in the cylinder might 



