REVIEWS 531 



no fewer than 382 with answers. The author has not, however, made a sufficient 

 effort to raise the subject above the rather uninspiring level of a branch of applied 

 mathematics, and the absence of all reference to the experimental and historical 

 sides of the work is very regrettable. A treatment which gives little or no account 

 of the work of Joule and of Meyer, of Kelvin and of Clausius, and which does not 

 as much as mention Rumford, is distinctly incomplete. A clearly reasoned 

 statement of Carnot's work is almost essential if the subject is to become a live 

 one to the engineer ; the mere dry bones — a cycle treated along with, and at not 

 much greater length than, Ericsson's and Otto's, and a mangled statement of 

 Carnot's Principle — are not enough. 



Perhaps the weakest thing in the whole book is the proof of the identity of 

 Kelvin's thermodynamic scale with the absolute gas scale (which is only defined 

 implicitly). The student is referred to one of Calendar's papers for the numerical 

 value of the efficiency of a Carnot cycle with air as working substance. Since the 

 efficiency has already been worked out for a perfect gas, this is as unnecessary as 

 it is inconclusive to the novice. Indeed, the whole of Kelvin's treatment of this 

 question is best relegated to an appendix. 



The chapters on vapours and vapour cycles are excellent, and such questions 

 as entropy and total heat are treated very carefully. The notation, however, is 

 not very suggestive, and the equations here (and throughout the book) are given 

 a clumsy appearance by the continual insertion of the mechanical equivalent J in 

 the denominator of the work terms. A direct proof of the Clapeyron equation for 

 the liquid-vapour change is desirable, for it appeals far more to the engineer than 

 that given by the Maxwell relations. The flow of fluids, with special regard to the 

 turbine, is discussed at length, and the book closes with an account of the differential 

 equations of thermodynamics. 



It ought to be pointed out that the author has attempted to explain clearly 

 what is meant by a reversible cycle, and that he does not confuse adiabatics and 

 isentropics — a rare virtue indeed ! On the other hand, he has permitted himself 

 to use a system of spelling which cannot but prejudice his book in this country. 

 " Thru," " thoroly," " enuf," " gage," are fortunately not. yet tolerated in English 

 orthography, however legitimate they may be in American. 



D. Orson Wood. 



The Thermo-dynamic Properties of Ammonia. By Frederick G. Keyes 

 and Robert B. Brownlee. [Pp. v + 74, with 7 figures, numerous 

 tables and large Mollier diagram.] (New York : John Wiley & Sons, Inc. 

 London : Chapman & Hall, Ltd., 1916. Price 4s. 6d. net.) 



The Government and the scientific and technical institutions of the United 

 States of America have done and are doing a vast amount of scientific work 

 of direct and immediate value to trade, industry, and commerce. Refrigeration, 

 in its many sub-divisions, has received special attention and affords a striking 

 example of what pure science can do for commerce and incidentally points the 

 way to the men of science (and Government) of this country. 



The work under review was " computed for the use of engineers from 

 experimental data derived from investigations made at the Massachusetts Institute 

 of Technology " with the hope that it " would prove useful in controlling the 

 performance of refrigerating machines." 



The whole research has been carried out on the soundest possible lines — both 

 from the scientific and utility points of view. The authors in their Preface state : 

 " After the completion of the preliminary work, in connection with which the 



