February 27, 1896] 



NATURE 



38: 



discussed in detail. His own remarks on this point 

 afford a clear example of the means by which the 

 unnecessary size of the volume has been attained. 



In Book i., Chapter v., numerous examples of co- 

 operation in nature are quoted from various writers, and 

 it seems to the author "to be quite impossible to har- 

 monise the demands of the theory of natural selection 

 . . . with the co-operation which is constantly found in 

 nature." 



In attempting to account for the extermination of the 

 l)lack rat by the brown, on other grounds than those of 

 natural selection pure and simple, we meet with the 

 suggestion (pp. 107, 108) that the proportion of brown 

 females was increas ed in consequence of the proteid diet 

 of black rats I 



Upon the destruction of the watercress in the New 

 Zealand streams by means of the willow, he remarks — 

 " There is no abstract survival of the fittest : both are 

 equally fit apart from one another." 



The work is divided into three books, each of which 

 ' ontains seven chapters. The first book discusses the 

 possibility, the third the evidences of natural selection, 

 while the second compares it with other attempts to 

 explain evolution. 



It would have been far better if the author could have 

 found " peace " — to use his own phraseology — by per- 

 forming a task of less herculean proportions. In these 

 days of hurry and hard work the world will find it difficult, 

 if not impossible, to absorb a message which requires 591 

 jtages to deliver. E. B. P. 



OUR BOOK SHELF. 

 Minerals, and how to Study them : a Book for Beginners 



in Mineralogy. By Edward Salisbury Dana. 8vo, 



380 pp. ; 319 figs. (New York : Wiley and Sons. 



London : Chapman and Hall, 1895.) 

 A GLANCE at this volume is sufficient to show that we 

 have here a book of the sort which is wanted for quite 

 elementary students. A sentence chosen at random from 

 the introductory chapter will indicate at once how it differs 

 from the ordinary text-books, both in style and method. 

 Speaking of the trial ofhardness, the author says : " It is 

 necessary to be sure and distinguish between a real 

 scratch on a smooth surface and the crushing of a rough 

 surface by the knife-edge ; a very hard mineral may 

 often be scratched in this way. The danger of making 

 a mistake of this kind is made less if, besides the useful 

 knife-point, the mineral be rubbed on a piece of glass ; 

 better have a piece at hand (not disfigure a window- 

 pane). Only do not make the opposite mistake and call 

 a white ridge left by a soft mineral on the glass, which 

 can be easily rubbed off, a scratch." Here is a real 

 attempt to guide the beginner through the pitfalls which 

 beset an unwary student ; how different from the usual 

 bald statement of facts, in which the possibility of any 

 difficulty which may occur is not even mentioned. The 

 same is true of the excellent chapter on blowpipe- 

 testing ; thus : " Another trial may be made with 

 sphalerite or zinc blende, but to succeed now the mineral 

 should be pulverised first, since it is infusible before the 

 blowpipe, and the compound is only with difficulty 

 decomposed on charcoal," &c. 



It is of course difficult to maintain this style of writing 

 when the author comes to the description of the various 

 mineral species, but in that portion of the book also he 



NO. 1374, VOL. 53] 



has contrived to present the facts in attractive language 

 and make them interesting to an elementary student, 

 and he is content to describe only the most important 

 minerals ; the smaller text-books at present available, 

 excellent though they may be in other respects, are 

 usually condensed epitomes of the larger treatises ; they 

 contain too much, and are not written in simple language 

 calculated to engage the attention of beginners. 



The book closes with an excellent chapter on the 

 determination of minerals, full of useful and suggestive 

 hints. 



As might be expected from the author, or joint-author, 

 of the best and most exhaustive treatise on minerals 

 which exists. Prof. Dana's book, though elementary, 

 maintains throughout a high standard of scientific 

 method. 



From the educational point of view, we note some 

 striking defects due to the use of language which, though 

 picturesque, may be misunderstood by a beginner. For 

 example, the statement that "the reflecting goniometer 

 demands polished faces if good results are to be obtained," 

 will inevitably suggest the need of artificial polish to the 

 student who takes all things literally ; a similar mis- 

 understanding will be produced by the description of 

 Chalcotrichite as a variety of Cuprite, in which " the 

 cubes are spun out into long threads." 



The illustrations are mostly new, and among them are 

 many good pictures of typical minerals ; it is only un- 

 fortunate that the figures of the simple forms and com- 

 binations in the third chapter are so shaded that the faces 

 appear concave. These defects can be easily corrected 

 in a second edition, and do not detract from the merits 

 of the book as a really useful and attractive introduction 

 to mineralogy, which can be safely recommended to 

 beginners. H. A. M. 



Heating and Ventilating Buildings. By Rolla C. Car- 

 penter, Professor of Experimental Engineering, Cornell 

 University. Pp. 400. (New York : John Wiley and 

 Sons. London : Chapman and Hall, Limited, 1895.) 

 The subject of heating and ventilating buildings has of 

 late years been more and more considered by engineers 

 in this country. In the United States, on the other hand, 

 the question has received satisfactory treatment, and 

 we have therefore much to learn from the systems in 

 vogue there. The object of this volume is to present to 

 the reader a general idea of the principles which apply, 

 and of the methods of construction usually adopted in 

 various systems of heating and ventilating. The author 

 deals with the subject in a clear and concise manner, the 

 information given being the result of extensive practice 

 in designing and operating heating apparatus. Taken as 

 a whole, the volume is of much value ; it is well printed 

 and nicely bound. 



The author divides the matter into sixteen chapters, 

 commencing with a description of the " nature and 

 properties of heat"; he very fully enumerates the many 

 laws pertaining thereto. On the general principles of 

 ventilation we find much useful information. Some ex- 

 periments made by Mr. Warren R. Briggs, of Bridge- 

 port, Conn., on the subject of the proper method of intro- 

 ducing pure air into rooms, and the best location for the 

 inlet and outlet, are described. The illustrations show- 

 ing graphically the results are highly interesting, the 

 best being obtained by placing the air inlet on the 

 side of the room near the top, and the outlet in the 

 bottom and near the centre of the room. The outlet, of 

 course, must be connected with a flue of ample size, and 

 maintained at a temperature higher than that of the 

 surrounding air. Many authorities are quoted, and 

 extracts from technical papers are given. The loss of 

 heat through walls of various thicknesses is pointed out, 

 and Mr. Alfred R. Wolff's lecture before the Franklin 



