270 



SCIENCE. 



[N. S. Vol. I. No. 10. 



infer from the title of the book that such ex- 

 cursions are avoided. The scope and char- 

 acter of the work may be best inferred from 

 the following paragraphs of the preface : 



"The aim of the present Treatise on 

 Hj^drostatics is to develop the subject from 

 the outset by means of illustrations of ex- 

 isting problems, chosen in general on as 

 large a scale as possible, and carried out to 

 their numerical results ; in this way it is 

 hoped that the student will acquire a real 

 working knowledge of the subject, while at 

 the same time the book will prove useful to 

 the practical engineer." 



" In accordance with modern ideas of 

 mathematical instruction, a free use is 

 made of the symbols and operations of the 

 Calculus, where the treatment requires it, 

 although an alternative demonstration by 

 elementary methods is occasionally submit- 

 ted ; because, as has well been said, "it is 

 easier to learn the differential calculus than 

 to follow a demonstration which attempts to 

 avoid its use." 



Too much stress cannot be laid on this 

 remark with regard to the role of the cal- 

 culus in applied science. We are coming 

 now, after two centuries, to realize clearly 

 that the use of the calculus has become gen- 

 eral in all higher investigations, not because 

 the pure mathematicians have so desfred, 

 but because the phenomena of nature de- 

 mand for their interpretation such an instru- 

 ment of research. 



The book is a mine of interesting and 

 useful information, and must become one 

 of the standards for students, teachers and 

 engineers. The principles are illustrated 

 by a wide variety of good examples, many 

 of which are drawn from practical applica- 

 tions. Special attention is given to the 

 problems of flotation and stability of ships, 

 and to problems arising in naval architec- 

 ture. The theory of the various hydrostat- 

 ic instruments, including the hydrometer, 

 the barometer and the gas thermometer, is 



worked out quite fullj-. A chapter is de- 

 voted to pneumatics, and another to pneu- 

 matic machines. There are also chapters 

 on capillarity, hydraulics, the general equa- 

 tions of equilibrium, and on the mechanical 

 theory of heat. In shoi't, the work is a very 

 comprehensive one. Few books contain 

 more information per page, and few abound 

 to such an extent in historical references. 



The exposition of the author is in general 

 clear and logical, though occasionally an , 

 important principle is announced without 

 due warning. Thus, Bernoulli's theorem 

 appears without demonstration on p. 467 in 

 the chapter on hydraulics. It would have 

 been more in accord with the admirable 

 spirit of the book, we think, if the author 

 had given in that chapter the general equa- 

 tions of fluid motion, and thence deduced 

 Bernoulli's theorem, even if this enlarge- 

 ment had required a change in the title of 

 the work. 



Some obscurity arises here and there from 

 the author's habit of condensation. Thus, 

 on p. 458 we read, " so that the attraction 

 of pure gravitation on a plummet weighing 

 TFg is WG dynes, where G denotes the ac- 

 celeration of gravity." Of course, the ex- 

 pert would quickly see that TFg means W 

 grammes, but the average engineer will not 

 commend such economy. 



The book has a good, but not quite good 

 enough, index. For example, the unusual 

 words barad and spoud are occasionally 

 used by the author. Their meaniag is plain 

 from the context, in most cases, to the 

 specialist, but the general reader would not 

 get any light on these terms from the in- 

 dex ; for it does not contain the word spoud, 

 while it refers for barad to a page on which 

 this word does not occur. 



These faults, however, are small ones, 

 and such, moreover, as are well-nigh in- 

 separable from the first edition of a book so 

 full of sound knowledge as this one. 



E. S. WOODWAED. 



