66o 



NA TURE 



[October 29, 1908 



architect and ninrine eng'iiieer. In these sections of 

 the book considerable use is made of information 

 published in the Transactions of the Institution of 

 Naval Architects and other technical publications, 

 always with due acknowledgment. 



There are six chapters. The first deals with 

 "stream-lines," mainly following Rankine's methods, 

 but also discussing Prof. Hele Shaw's interesting 

 experiments on viscous stream-line flow and Sir 

 George Stokes's mathematical investigations thereon. 

 Next an excellent summary is given of the theorv of 

 w-ave-motion ; for waves of translation and oscilla- 

 tion, and for capillary waves. Methods of observing 

 ocean waves, and some results of such observations, 

 are also described. In this section reference is made to 

 original work done by Prof. Osborne Reynolds in con- 

 nection with groups of waves. 



Two interesting chapters — making up about one- 

 fourth of the book — are devoted to an epitome of 

 modern methods of determining the resistance of ships, 

 due for the most part to the work of William Froude, 

 whose enunciation of the " law of comparison " be- 

 tween ships and models, and investigations of frictional, 

 eddy-making, and wave-making resistance are 

 described in detail. Since the system of model- 

 experiments was introduced by Froude about forty 

 years ago, great extensions have taken place in the 

 trials made with full-sized ships, and the comparisons 

 of the results of such trials with those obtained with 

 model ships and propellers have yielded much valu- 

 able information. This result is illustrated in manv 

 ways by the author, in a chapter dealing with the 

 trials of ships. Considerable interest will be taken 

 in the discussion of the influence which depth of 

 luater has upon the resistance of ships, especially in 

 view of certain extraordinary results obtained on" the 

 trials of some recent torpedo-boat destrovers. In a 

 final chapter the characteristics and relative efficiencies 

 of water-jet propellers, paddle wheels, and screw pro- 

 pellers are discussed at length, the work of the 

 two Froudes, Rankine, Cotterill, and Charies Parsons 

 being utilised. No part of the book shows greater 

 labour than this in its assemblage and analysis of 

 facts and theories. A good index completes the 

 volume. 



On its merits the book deserves, and will receive, 

 favourable recognition from all interested in the 

 subjects of which it treats. That recognition will not 

 be lessened by the fact that its appearance is coin- 

 cident with a serious breakdown in health of its 

 gifted author, involving his resignation of the pro- 

 fessorship of civil and mechanical engineering in the 

 University of Manchester. To this circumstance may 

 be attributed certain errors m mathematical formulje 

 occurring in the book, and these should be corrected 

 in future editions. There is evidence, too, that the 

 book was, for the most part, completed some time 

 ago; as it gives no account of valuable experimental 

 investigations made during the last two or three 

 years in this country and the United States. As it 

 stands it may be recommended as a text-book for the 

 use of students, working under the guidance of com- 

 petent teachers. 



NO. 2035, VOL. 78] 



STUDIES 



OF 



this 



' the 



and 



;.V THE STATISTICS 



PRODUCTION. 

 Kraft: Okoiioiiiisclic, technische und huUnrgeschicht- 

 liche Studien iiber die Machtentfaltuiig der Staaten. 

 By Prof. E. Reyer. Pp. xvi + 380. (Leipzig : W. 

 Engelmann, 190S.) Price 6 marks. 



THE subject with which Dr. Reyer deals in 

 volume is an extremely wide one, viz. 

 supply and consumption of human, animal 

 mechanical and thermal energy for domestic purposes 

 and in agriculture, industry and transport." Prac- 

 tically speaking, the subject, as he interprets it, is 

 coterminous with what is usually understood by the 

 statistics of production, and we cannot help thinking 

 that some such title would have better described the 

 work. Dr. Reyer deals not merely, or even princi- 

 pally, with statistics of power as such, but with the 

 means of obtaining heat and power, the uses to which 

 it is put, and even the organisation of industry. The 

 replacement of handwork by wholesale manufacture, 

 the output of coal, the development in the use of steel, 

 transport by land and sea, agriculture, gas and electric 

 lighting all come under his survey. 



The labour that Dr. Reyer must have spent on his 

 work and on the preparation of the numerous illustra- 

 tive diagrams is immense, and some of his studies 

 serve to emphasise very well the great changes that 

 have taken place of recent years in the industries of 

 the world, and more especially in the relative positions 

 of Germany, Great Britain, and the United States — 

 the three countries to which the author devotes most 

 of his attention. Taking the volume as a whole, how- 

 ever, we do not think that Dr. Reyer can be said 

 to have fulfilled his task very happily, though it will 

 be readily conceded that many difficulties are inherent 

 in the subject. The data are very imperfect, usually 

 incomplete, and nearly always incomparable as be- 

 tween one country and another. Still, there are data, 

 and the volume might, we think, have been made 

 both more readable and more useful to the student. 



In the first place, the chapters read as if they were 

 isolated studies, made at different times, and subse- 

 quently thrown together with little or no attempt at 

 arrangement. The first three are entitled " The Age 

 of Steel," " Mining and the Importance of Coal," 

 and " The Noble Metals " respectively, and form to 

 some extent a connected series. The reader expects 

 the following chapters to deal with other industries, 

 but chapter iv. treats of the growth of population and 

 development of industry in the case of the Great 

 Powers, chapter v. passes to the industries of a single 

 country — the United States — chapter vi. gives a general 

 discussion on the subject of wholesale manufacture 

 and handwork, and the next chapter deals with 

 economic fluctuations ! After this we come to trans- 

 port and then to agriculture. The book has no obvious 

 structure or plan, and the erratic changes of subject 

 are most distracting to the reader. 



In the second place, references are almost entirely 

 lacking. There are few or none in the text, and a 

 hopelessly inadequate bibliography at the end of the 

 volume, a bibliography which suggests that the author 

 must have taken much of his information at second 



