THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JULY 1851. 



I. On the Moving Force of Heat, and the Laws regarding the 

 Nature of Heat itself which are deducible therefrom. By 

 R. Clausius*. 



THE steam-engine having furnished us with a means of con- 

 verting heat into a motive power, and our thoughts being 

 thereby led to regard a certain quantity of work as an equivalent 

 for the amount of heat expended in its production, the idea of 

 establishing theoretically some fixed relation between a quantity 

 of heat and the quantity of work which it can possibly produce, 

 from which relation conclusions 4'egarding the nature of heat 

 itself might be deduced, naturally presents itself. Already, in- 

 deed, have many instructive experiments been made with this 

 view ; I believe, however, that they have not exhausted the sub- 

 ject, but that, on the contrary, it merits the continued attention 

 of physicists ; partly because weighty objections lie in the way 

 of the conclusions already drawn, and partly because other con- 

 clusions, which might render eificient aid towards establishing 

 and completing the theory of heat, remain either entirely unno- 

 ticed, or have not as yet found sufficiently distinct expression. 



The most important investigation in connexion with this sub- 

 ject is that of S. Camotf. Later still, the ideas of this author 

 have been represented analytically in a very able manner by 

 Clapeyronf. Carnot proves that whenever work is produced by 

 heat, and a permanent alteration of the body in action does not 

 at the same time take place, a certain quantity of heat passes 



* Translated from PoggendorfF's Annalen, vol. Ixxix. p. 368. 



t Reflexions sur la puissance motrice dufeu, et sur les Machines propres 

 a developer cette puissance, par S. Carnot. Paris, 1824. 



X Journ. deVEcole Polytechniqy.e, vol. xix. (1834); and Taylor's Scien- 

 tific Memoirs, Part III. p. 347. 



Phil, Mag, S. 4. Vol. 2. No. 8. July 1851 . B 



^f 



