VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 279 



mass of metal ? If this were the case, then, according to the doctrine of latent 

 heat, and of caloric, the capacity for heat of the parts of the metal, so reduced to 

 chips, ought not only to be changed, but the change undergone by them should 

 be sufficiently great to account for all the heat produced. But no such change had 

 taken place : for I found, on taking equal quantities, by weight, of these chips, 

 and of thin slips of the same block of metal, separated by means of a fine saw, 

 and putting them, at the same temperature, that of boiling water, into equal quan- 

 tities of cold water, viz. at the temperature of 5Q% f., the portion of water into 

 which the chips were put was not, to all appearance, heated either less or more 

 than the portion, in which the slips of metal were put. This experiment being 

 repeated several times, the results were always so nearly the same, that I could 

 not determine whether any, or what change, had been produced in the metal, in 

 regard to its capacity for heat, by being reduced to chips by the borer. 



Hence it is evident, that the heat produced could not possibly have been fur- 

 nished at the expence of the latent heat of the metallic chips. But, not being 

 willing to rest satisfied with these trials, however conclusive they appeared to 

 me to be, I had recourse to the following still more decisive experiment. Taking 

 a cannon, a brass six-pounder, cast solid, and rough as it came from the foundry, 

 and fixing it horizontally in the machine used for boring, and at the same time 

 finishing the outside of the cannon by turning, I caused its extremity to be cut off; 

 and, by turning down the metal in that part, a solid cylinder was formed, 7-f- inches 

 in diameter, and Q-fe. 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 2± inches in diameter, and 3-^ inches long. This 

 short cylinder, which was supported in its horizontal 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 hol- 

 low cylinder, which bottom was 2.6 inches in thickness. 



The cylinder being designed for the express purpose of generating heat by fric- 

 tion, 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 accumu- 

 lated in the cylinder might from time to time be measured, a small round hole, 0.37 

 of an inch only in diameter, and 4.2 inches in depth, for the purpose of introducing 

 a small cylindrical mercurial thermometer, was made in it, on one side, in a direc- 

 tion perpendicular to the axis of the cylinder, and ending in the middle of the solid 

 part of the metal which formed the bottom of its bore. 



The solid contents of this hollow cylinder, exclusive of the cylindrical neck by 

 which it remained united to the cannon, were 3854- cubic inches, English measure; 

 and it weighed 113.13lb. avoirdupois ; as I found, on weighing it at the end of 



