476 Life of Count Rumford. 



which a brass gun so soon acquires in being bored. He 

 found, by experiment, that the metallic chips separated 

 by the borer had an intensity of heat exceeding that of 

 boiling water. He was persuaded that a thorough in- 

 vestigation of these phenomena would afford an insight 

 into the hidden nature of heat, and help to decide the ex- 

 istence or the non-existence of an igneous fluid, a point 

 on which the opinions of philosophers of all ages have 

 been divided. He put to himself the question, Whence 

 comes the heat actually produced in the mechanical 

 operation above mentioned ? Is it furnished by the metal- 

 lic chips which are separated from the solid mass of the 

 metal ? If so, then, according to the doctrines about 

 latent heat and 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 the test which compared some of these chips with 

 the same quantity of thin slips separated by a fine saw 

 from the same block of metal, proved that the capacity 

 of heat of the former had not been changed. It was 

 evident, then, that the heat produced by boring was not 

 furnished at the expense of the latent heat of the metal- 

 lic chips. Being assured of this fact for a starting- 

 point, the philosopher proceeded with a series of ex- 

 periments in the succession of which the elements of his 

 inquiry and the conditions for investigating them led 

 him to contrive apparatus, and to advance gradually to 

 his great discovery. Reminding his readers that he was 

 not chargeable with prodigality or waste of material in 

 these experiments, he informs us of an interesting fact 

 in the process of constructing a cannon of which he 

 availed himself. In the casting of a gun, he says, the 





