NA TURE 



^57 



THURSDAY, JANUARY 31, 1878 



T AIT'S ''THERMODYNAMICS'' 



Sketch of Thermodynamics. By P. G. Tait, M.A., for- 

 merly Fellow of St, Peter's College, Cambridge, Pro- 

 fessor of Natural Philosophy in the University of 

 Edinburgh. Second Edition, revised and extended. 

 (Edinburgh : David Douglas, 1877.) 



THIS book, as we are told in the preface, has grown 

 out of two articles contributed in 1864 by Prof. 

 Tait to the No'th British Review. This journal, about 

 that time, inserted a good many articles in which scien- 

 tific subjects were discussed in scientific language, and in 

 which, instead of the usual attempts to conciliate the 

 unscientific reader by a series of relapses into irrelevant 

 and incoherent writing, his attention was maintained by 

 awakening a genuine interest in the subject. 



The attempt was so far successful that the publishers 

 of the Review were urged by men of science, especially 

 engineers, to reprint these essays of Prof. Tait, but the 

 Review itself soon afterwards became extinct. 



Prof. Tait added to the two essays a mathematical 

 sketch of the fundamental principles of thermodynamics, 

 and in this form the book was published in 1868. In the 

 present edition, though there are many additions and 

 improvements, the form of the book is essentially the 

 same. 



Whether on account of these external circumstances, 

 or from internal causes, it is impossible to compare this 

 book either with so-called popular treatises or with those 

 of a more technical kind. 



In the popular treatise, whatever shreds of the science 

 are allowed to appear, are exhibited in an exceedingly 

 diffuse and attenuated form, apparently with the hope 

 that the mental faculties of the reader, though they would 

 reject any stronger food, may insensibly become saturated 

 with fcientific phraseology, provided it is diluted with a 

 sufficient quantity of more famihar language. In this 

 way, by simple reading, the student may become 

 possessed of the phrases of the science without having 

 been put to the trouble of thinking a single thought 

 about it. The loss implied in such an acquisition can 

 be estimated only by those who have been compelled to 

 unlearn a science that they might at length begin to 

 learn it. 



The technical treatises do less harm, for no one ever 

 reads them except under compulsion. From the estab- 

 lishment of the general equations to the end of the book, 

 every page is full of symbols with indices and suffixes, 

 so that there is not a paragraph of plain English on 

 which the eye may rest. 



Prof. Tait has not adopted either of these methods. 

 He serves up his strong meat for grown men at the 

 beginning of the book, without thinking it necessary to 

 employ the language either of the nursery or of the 

 school ; while for younger students he has carefully 

 boiled down the mathematical elements into the most 

 concentrated form, and has placed the result at the end 

 as a bonne bouche, so that the beginner may take it in all 

 at once, and ruminate upon it at his leisure. 



A considerable part of the book is devoted to the 

 Vol. xvii. — No. 431 



history of thermodynamics, and here it is evident that 

 with Prof. Tait the names of the founders of his science 

 call up the ideas, not so much of the scientific documents 

 they have left behind them in our libraries, as of the men 

 themselves, whether he recommends them to our reverence 

 as masters in science, or bids us beware of them as 

 tainted with error. There is no need of a garnish of 

 anecdotes to enliven the dryness of science, for science 

 has enough to do to restrain the strong human nature 

 of the author, who is at no pains to conceal his own 

 idiosyncrasies, or to smooth down the obtrusive antinomies 

 of a vigorous mind into the featureless consistency of a 

 conventional philosopher. 



Thus, in the very first page of the book, he denounces 

 all metaphysical methods of constructing physical science 

 and especially any d priori decisions as to what may 

 have been or ought to have been. In the second page he 

 does not indeed give us Aristotle's ten categories, but he 

 lays down four of his own : — matter, force, position, and 

 motion, to one of which he tells us, " it is evident that 

 every distinct physical conception must be referred," and 

 then before we have finished the page we are assured that 

 heat does not belong to any of these four categories, but 

 to a fifth, called energy. 



This sort of writing, however unhke what we might 

 expect from the conventional^man of science, is the very 

 thing to rouse the placid reader, and startle his thinking 

 powers into action. 



Prof. Tait next handles the caloric theory, but instead 

 of merely showing up its weak points and then dismissing 

 it with contempt, he puts fresh life into it by giving (in the 

 new edition) a characteristic extract from Dr. Black's 

 lectures, and proceeds to help the calorists out of some of 

 their difficulties, by generously making over to them some 

 excellent hints of his own. 



The history of thermodynamics has an especial inter est 

 as the development of a science, 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 

 foundations, clear definitions, and distinct boundaries. 



The earlier part of the history has already provoked a 

 sufficient amount of discussion. 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 himself to the greatest extent of the 

 scientific use of the imagination. His imagination, how- 

 ever, though amply luxuriant, was strictly scientific. 

 Whatever he imagined about molecular vortices, with 

 their nuclei and atmospheres, was so 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 dis- 

 tribution of his vortices may seem to us as complicated 

 and arbitrary as the Cartesian system, his final deduc- 

 tions are simple, necessary, and consistent with facts. 



Certain phenomena were to be explained. Rankine 



