472 Ingimy conce^niing the Source of 



spects, and worthy of the honour of being made known 

 to the Royal Society. 



Being engaged lately in superintending the boring of 

 cannon in the workshops of the military arsenal at 

 Munich, 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 experi- 

 ment) of the metallic chips separated from it by the 

 borer. 



The more I meditated on these phaenomena, the more 

 they appeared to me to be curious and interesting. A 

 thorough investigation of them seemed even to bid fair 

 to give a farther insight into the hidden nature of Heat ; 

 and to enable us to form some reasonable conjectures re- 

 specting the existence, or non-existence, of an igneous fluids 

 — a subject on which the opinions of philosophers have 

 in all ages been much divided. 



In order that the Society may have clear and distinct 

 ideas of the speculations and reasonings to which these 

 appearances gave rise in my mind, and also of the spe- 

 cific objects of philosophical investigation they suggested 

 to me, I must beg leave to state them at some length, 

 and in such manner as I shall think best suited to an- 

 swer this purpose. 



From whence comes the Heat actually produced in the" 

 mechanical operation above mentioned ? 



Is it furnished by the metallic chips which are sepa- 

 rated by the borer from the solid mass of metal } 



If this were the case, then, according to the modern 

 doctrines 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 



