ACCEPTS CONVERSION OF WORK INTO HEAT. I 1 9 



points out but dwells upon ; while the only acceptance which 

 this note contains is the discovery, and this in its narrowest 

 sense, of the conversion of the mechanical effect into heat. 



Notwithstanding the denials, however, the admission by 

 such a physicist, however small in itself, was an indication 

 of great things. It was the thin end of the wedge, or the 

 first drop that indicated that the tide of highest scientific 

 thought had overtopped the obstructing bank of pre- 

 conceived opinions, which it forthwith began to sweep away. 



Sir William Thomson's next paper, "An account of 

 Carnot's theory of the Motive Power of Heat ; with its 

 Numerical Results derived from Regnault's Experiments on 

 Steam," was read before the Royal Society of Edinburgh, 

 January 2, 1849. This paper shows that the writer has, 

 since the last paper, been studying and considering Joule's 

 published researches, to which he now pays considerable 

 deference. He still continues to use the assumption that 

 heat is not converted into work as the foundation of Carnot's 

 theorem, but precedes this assumption by the following 

 qualification in the text of his paper : " The extremely 

 important discoveries recently made by Mr. Joule, of Man- 

 chester, that heat is evolved in every part of a closed electric 

 conductor moving in the neighbourhood of a magnet; and 

 that heat is generated by the friction of fluids in motion, 

 seems to overturn the opinion generally held that heat 

 cannot be generated but only produced from a source, 

 where it has previously existed either in a sensitive or 

 latent condition." 



" In the present state of science, however, no operation 

 is known by which heat can be absorbed into a body 

 without either elevating its temperature, or becoming latent 

 and producing some alteration in its physical condition;" 



