TJUT'S "THERMODYNAMICS." 



into it by giving (in the new edition) a characteristic extract from Dr Black's 

 and proceeds to help the calorists out of some of their difficulties, by 

 ikinir over to them some excellent hints of his own. 



H *j iiiia^a^ ^ 



The hiatory of thermodynamics has an especial interest as the development 

 of a acienee, within a short time and by a small number of men, from the 

 condition of a vague anticipation of nature to that of a science with secure 

 famdatiwE, clear definitions, and distinct boundaries. 



The earlier part of the history has already provoked a sufficient amount 

 of dincuauon. We shall therefore confine our remarks to the methods employed 

 for the advancement of the science by the three men who brought the theory 



to maturity. 



Of the three founders of theoretical thermodynamics, Rankine availed him- 

 elf to the greatest extent of the scientific use of the imagination. His 

 imagination, however, though amply luxuriant, was strictly scientific. Whatever 

 he imagined about molecular vortices, with their nuclei and atmospheres, was 

 M> clearly imaged in his mind's eye, that he, as a practical engineer, could 

 see how it would work. 



However intricate, therefore, the machinery might be which he imagined 

 to exist in the minute parts of bodies, there was no danger of his going 

 on to explain natural phenomena by any mode of action of this machinery 

 which was not consistent with the general laws of mechanism. Hence, though 

 the construction and distribution of his vortices may seem to us as complicated 

 and arbitrary as the Cartesian system, his final deductions are simple, necessary, 

 and consistent with facts. 



Certain phenomena were to be explained. Rankine set himself to imagine 

 the mechanism by which they might be produced. Being an accomplished 

 engineer, he succeeded in specifying a particular arrangement of mechanism 

 competent to do the work, and also in predicting other properties of the 

 mechanism which were afterwards found to be consistent with observed facts. 



As long as the training of the naturalist enables him to trace the action 

 only of particular material systems without giving him the power of dealing 

 with the general properties of all such systems, he must proceed by the method 

 so often described in histories of science he must imagine model after model 

 of hypothetical apparatus till he finds one which will do the required work. 

 If this apparatus should afterwards be found capable of accounting for many 

 of the known phenomena, and not demonstrably inconsistent with any of them, 



