MODERN THEORIES OF HEAT AND LIGHT 



in refutation of the experiments of Bowditch, that no 

 body either gains or loses weight in virtue of being 

 heated or cooled. He thought he had proved that heat 

 is only a form of motion. 



His experiment for producing indefinite quantities 

 of heat by friction is recorded by him in his paper en- 

 titled, " Inquiry Concerning the Source of Heat Excited 

 by Friction." 



" Being engaged, lately, in superintending the bor- 

 ing of cannon in the workshops of the military arsenal 

 at Munich," he says, "I was struck with the very 

 considerable degree of heat which a brass gun acquires 

 in a short time in being bored ; and with the still more 

 intense heat (much greater than that of boiling water, 

 as I found by experiment) of the metallic chips sep- 

 arated from it by the borer. 



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

 and rough, as it came from the foundiy, and fixing it 

 horizontally in a machine used for boring, and at the 

 same time finishing the outside of the cannon by turn- 

 ing, I caused its extremity to be cut off ; and by turning 

 down the metal in that part, a solid cylinder was 

 formed, yj inches in diameter and q*-^j 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. 



209 



