October 9, 1890] 



NATURE 



567 



animal magnetism, Dr. Moll practically admits an un- 

 explained residuum of facts, and in the candid temper 

 of his whole book, shows a truly scientific spirit of 

 genuine interest in their investigation, 



A . T. Myers. 



OUR BOOK SHELF. 



Text-book of Mechanics. By Thomas Wallace Wright. 

 (New York: D. Van Nostrand Company, 1890.) 



This book is a most excellent treatise on the science of 

 mechanics, and systematically places before the student 

 the principles which underlie the subject. The differen- 

 tial calculus for the most part is used only when a clear 

 advantage is gained by it, and in the earlier chapters of 

 the work two courses are open to the reader, one with and 

 the other without it. The author in a note rather regrets 

 that words for the unit velocity and unit acceleration have 

 not been proposed, as these would simplify matters : the 

 Rev. J. B. Lock, in his late book on "Dynamics for 

 Beginners," has proposed and used two very good words, 

 " velo " and "celo," for unit velocity and unit acceleration 

 respectively. 



On the whole, the practical parts are treated more fully 

 than is usual, and the examples throughout are of a very 

 practical and typical character, and not mere numerical 

 illustrations of formulee. Many examples the author has 

 treated by the graphical method of solution, but he adds 

 a word of warning to the student against making it a 

 complicated weapon for attacking all sorts of problems 

 which are more easily solved in other ways. 



Another important point alluded to is the use of 

 approximate formulas : the rigorous formula always pre- 

 cedes the approximate one, the latter being reduced from 

 the former, so that the degree of approximation can easily 

 be estimated. 



The last two chapters deal with the statics and kinetics 

 of fluids, or, as they are more generally known, hydro- 

 statics and hydrokinetics. 



Besides numerous examples there are plenty of figures 

 and woodcuts, and scattered here and there are a {t.\f 

 historical notes which give a lively interest to the subject. 



W. 

 An Elementary Text-book of Heat and Light. By R. 

 Wallace Stewart, B.Sc. London. (London : W. B. 

 Clive and Co., 1890.) 

 This volume is one of the University Correspondence 

 College Tutorial Series, which are written specially to 

 meet the requirements of the various London University 

 examinations. 



Of the twenty chapters, the first ten deal with the 

 principles which underlie the theory of heat, while the 

 second ten treat of those of light. In each chapter the 

 principles and laws on which the subject-matter depends 

 are fully described, and under the heading of " Calcula- 

 tions" the author explains the various laws in mathematical 

 form, concluding with examples worked out, and in many 

 cases questions from well-known examinations. The 

 chapters on light are treated in a similar manner. Those 

 reading this work should be able to obtain a fair grip of 

 these two subjects, the elementary principles being well 

 and concisely expressed. 



At the beginning of the second part of the book, on 

 ■' Light," the author recommences the numbering of the 

 pages, which we think is rather a mistake, as it is awkward 

 in the first instance for reference, and in the second it has 

 necessitated the use of two indexes. The illustrations, 

 one hundred and fifty in number, are very good and 

 accurate, and the work concludes with an appendix con- 

 taining a paper of questions set at the London Matricu- 

 lation examinations under the new 1888 regulations. 



W. 



The Confessions of a Poacher. Edited by John Watson, 



F.L.S. (London : The Leadenhall Press, 1890.) 

 In an editorial note it is stated that the poacher of these 

 " Confessions " is "no imaginary being." Since that is 

 so, it might have been well for Mr. Watson to explain 

 the precise nature of his own functions as editor. It 

 seems rather odd to find a poacher talking in this way : — 

 " It was the fact that I had, during the small hours of 

 the morning, stood alone on London Bridge. The great 

 artery of life was still ; the pulse of the city had ceased 

 to beat. Although bred among the lonely hills, I felt for 

 the first time that this was to be alone ; that this was 

 solitude. I felt such a sense as Macaulay's New Zea- 

 lander may experience when he sits upon the ruins of the 

 same stupendous structure." How much of this is the 

 poacher's, and how much are we to attribute to the 

 editor t The same question often suggests itself, and a 

 good many readers, we suspect, will conclude that at 

 least with the form of the " Confessions " the person 

 supposed to be confessing has had very little to do. The 

 book displays a curious and intimate acquaintance with 

 some forms of animal life, and may be of service in 

 fostering a liking for natural history. Unfortunately, 

 however, grammatical rules are not always treated with 

 the respect which is due to them. Says the poacher : 

 '■ Whilst preparing my nets and wires, the dogs would 

 whine impatiently to be gone." No doubt the poacher 

 here means that he himself prepared his nets and wires, 

 but what he says is that the dogs prepared them. 



Examination Papers in Trigonometry. By George H. 

 Ward, M.A. (London : George Bell and Sons, 1890.) 

 One hundred and twenty examination papers are given 

 in this book ; they are arranged progressively and seem 

 to be well chosen, and will be found good substitutes for 

 the questions in the various text-books which become 

 familiar to the student on his second reading. Questions 

 solely on book-work collected together at the end form a 

 useful addition. 



Blackie's Modern Cyclopaedia. Vol, VII. Edited by 

 Charles Annandale, M.A., LL.D. (London : Blackie 

 and Son, Limited, 1890.) 



This is the seventh volume of this useful and valuable 

 essence of information, commencing with the word " Pota- 

 mogeton" and reaching as far as " Skates." The articles 

 on the various subjects are generally well treated, and 

 every reader may find something of interest in them ; 

 numerous pictorial illustrations and maps are given. The 

 references to printing, Prussia, railways, Rome, Russia, 

 and Scotland are among the most lengthy in this volume. 



NO. 



1093, VOL. 42] 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. \ 



Recent Classification of the Shrews. 



During the present year some very important work has been 

 done with the Soricidce, the family of the Shrews. This has 

 been mainly contributed by the well known student of the group, 

 Dr. George E. Dobson, F.R.S., the distinguished mammalogist. 

 Dr. Dobson has just published the first fasciculus of Part III. 

 of his work entitled *' A Monograph of the Insectivora, Syste- 

 matic and Anatomical" (Gurney and Jackson, London). This 

 fasciculus deals entirely with the Shrews, it being a quarto 

 illustrated by six fine lithographic plates fully illustrating the 

 dentition of the Soricidce, as its text, in the most admirable 

 manner, presents their characters. Even a still more important 

 paper by the same author appeared in the Proceedings of the 



