ON THE PHYSICAL VIEW OF NATUKE. 103 



practical application of scieutiHc knowledge. lilack's 

 experiments and measurements contributed largely to 

 fix the difference between temperature and ([uantity 

 tif heat ; he demonstrated clearly that heat may 

 disappear in the form of temperature and exist 

 as latent heat, ihal is, licat not discoverable by 

 the thermometer. He, however, adhered to the view 

 that heat was a material substance, whicli, tliough 

 it mi^ht become latent, did n(jt disappear as such. 

 Itumford^ was the first who definitely went a step further 

 and suggested the convertibility of heat and mechanical 

 work. It was not the disappearance of heat but its 

 appearance when mechanical work was performed whicli 

 attracted his attention. After eliminating all the 

 sources from which the heat produced during the bor- 

 ing of cannon could have been derived, he comes to the 

 conclusion that " it appears to be extremely ditticult, 

 if not quite impossible, to form any distinct idea of 

 anything capable of Ijeing excited and communicated 

 in the manner the heat was excited and communicated 

 in those experiments, except it be motion." Uavy, 

 who, like lUack, approached science in tlie interests of 

 the medical man, comes to the conclusion in his firet 

 published papers, from experiments on the generation 



^ Count Rumford's "Inquiiy con- 

 cerning the Source of the Heat 



republislied in America and trans- 

 lated into several foreign lan- 



which is excited by Friction" was | guages. See Uuinford's 'Works,' 



published in a later edition of his London, 1876, vol. i. p. 48'2, 



'Ussays.' The experiments with and vol. ii. p. 471. In 1804 



the boring of cannon were cairied Count Rumford imblished, in lii.s 



on at Munich in 1796 and 17f>7 ; ' Meiuoires sur la Clialcur ' [VuriA, 



the substance of the essay was an. 13), a " Historical Review oi 



read before the Roval Society in j the Various Experiments on Heat " 



Januarv 1798. The*' Essays ' were | (' Works,' vol. iii. pp. 138-240). 



