2l8 



NA TURE 



[December 24, iqo8 



designed for the use of students in their second college 

 term. Each preparation is introduced by a short 

 theoretical discussion of the reaction involved, fol- 

 lowed by details of procedure, and a number of sug- 

 gestive questions which the student is required to 

 answer in his note-book. The scheme is excellent, 

 and if conscientiously followed should afford an intelli- 

 gent student the full laenefit of each experiment. He 

 is not supposed to work right through the book, but 

 the experiments are to be distributed among the 

 students, who are encouraged to be inquisitive as 

 regards their neighbours' activities, and so acquire 

 indirectly all that the book contains. Considering that 

 the matter is not very original, that there are no 

 illustrations, and only eighty-nine pages of print, the 

 price of 45. 6(i. seems rather high. 



(5) If "The Fundamental Conceptions of Chem- 

 istry " were printed as an aide-tnemoire for a candi- 

 date for the Inter. B.Sc, we should consider that the 

 179 small pages of compressed general chemistry might 

 serve a useful if not very dignified purpose. The book 

 is full of facts and theories laid down in didactic 

 fashion and with that want of precision and clear 

 exposition which characterise the tutorial text-book. 

 We cannot agree with the author that the book will 

 " accustom the student to the methods of chemical 

 reasoning," unless, of course, chemical reasoning is, 

 as one is sometimes inclined to think, a different 

 mental process from other kinds of reasoning. Nor 

 do we agree with him in admiring the elegance dis- 

 plaved in the get-up of his book. We must, however, 

 commend one special feature, namely, the historical 

 references, which are numerous and generally accu- 

 rate. It is interesting to learn the Christian names 

 of chemists, who do not usually appear to have any. 

 Such, for example, are Cato Maximilian Guldberg, 

 Peter Waage, and Eilhardt Mitscherlich ; Dulong and 

 Petit are, however, coupled together, as usual, without 

 Christian names. We should dissent from Dalton 

 being described as a Manchester schoolmaster, and 

 from the statement that owing to the discovery of 

 oxygen, " Lavoisier was able to realise what Mayow's 

 genius had arrived at a hundred years before." 



(6) Dr. Bryk's " Repetitorium " is what it pro- 

 fesses to be — a mere compilation of important facts 

 to assist the student's memory. It has been put 

 together apparently with great care, and there are 

 many useful tables containing a general summary of 

 compounds of different elements. To anyone desirous 

 of assimilating large quantities of information, the 

 book may be safely commended ; but we cannot 

 promise that he will be intellectually stimulated by its 

 perusal. J. B. C. 



OUR BOOK SHELF. 



Experiine>ital Elasticity. A Manual for the Labora- 

 tory. By G. F. C.'Searle, F.R.S. Pp. xvi-fiS;. 

 (Cambridge : University Press, 1908.) Price 55. net. 

 The author has embodied in this volume in a con- 

 nected form the contents of a number of manuscripts 

 whicli he had from time to time written for the use of 

 students attending his class in practical physics at the 

 Cavendish Laboratory. Chapters i. and ii., consisting 

 of 70 pages, give an account of the elementary theory 

 NO. 2043, VOL. 79] 



of elasticity, with solutions of some special mathe- 

 matical problems. Chapter iii., pp. 71-161, describes 

 the experiments — numbered i to 14 — prescribed for the 

 student. Pages 162-1S3 comprise ten short notes, 

 mostly on mathematical subjects. There is a table of 

 contents and an index. 



The experiments, which relate mainly to the deter- 

 mination of Young's modulus and the rigidity in 

 materials assumed isotropic, are very carefully de- 

 scribed. The apparatus, which seems mostly designed 

 by the author, is usually simple, and the student who 

 goes through the course intelligently should have 

 learned a good deal. The illustrations of Saint 

 Venant's principle of " equipollent " systems of force 

 in chapter ii., due to Dr. Filon, are likely to be useful. 



Notwithstanding the merits of the book, it is a little 

 difficult to picture" a student for whom it would form 

 the best possible introduction to the subject. The 

 reader who requires the notes at the end seems hardly 

 likely to follow the mathematical investigations into 

 the differences between adiabatic and isothermal elas- 

 ticity in chapter i., or into the bending of a rod and 

 the bending and twisting of a blade in chapter ii. 

 The ordinary student would probably get a better grasp 

 of the mathematical theory of elasticity from a study 

 of the ordinarv stress-strain and surface equations, and 

 their application to a few really simple problems. 



The author's attitude towards the application of 

 isotropic elasticitv to wires leaves something to be 

 desired. On p. 113 he gives a table of values of 

 Poisson's ratio obtained by the method of one of his 

 experiments. In five out of nine cases the value is 

 impossible, exceeding 0-5. The impossibility, it is 

 true, is pointed out, the phenomenon being ascribed to 

 lack of isotropy. But this is much as if a temperance 

 lecturer illustrated the evil effects of intemperance in 

 his own person. A safer course would be to confine 

 the table to cases where isotropy is at least not ob- 

 viously untenable, adding a warning that wires are 

 frequently neither isotropic nor homogeneous, and that 

 absurd results are often obtained by assuming that 

 they are. It would also be as well to let physical 

 students know that isotropy is not the only type of 

 elasticity amenable to mathematical treatment. Vibra- 

 tions in thin wires are theoretically a less satisfactory 

 method of finding elastic constants for materials than 

 are vibrations in long rods, but possibly Mr. Searle 

 is reserving vibrations in rods for one of the further 

 volumes adumbrated in his preface. C. Chree. 



Bcauiijul Flowers and How to Cron' Them. To be 

 completed in 17 parts. Edited by Horace J. Wright 

 and Walter P. Wright. With 100 coloured plates. 

 (London : T. C. and E. C. Jack.) Price 15. net 

 each part. 

 The first part is concerned entirely with roses, and 

 includes twenty-four pages of letterpress. The writer 

 discourses upon roses from the point of view of the 

 garden decorator rather than that of the ex- 

 hibitor, and, indeed, the mere exhibitor is given 

 very little consideration. This is verv natural 

 in such a work as this, which is undoubtedly intended 

 for amateurs who wish to grow flowers for their own 

 sake alone, and not for the glory that attends tlie 

 winning of prizes at competitive exhibitions. 



The style is pleasant, and the reader is given an 

 insight into the classification of roses in order to 

 enable him to understand the characteristics of the 

 numerous types. Even the novice may soon acquire 

 some knowledge of the hybrid teas, teas, hybrid per- 

 petuals, noisettes, moss rose, polyantha rose (Rosa 

 imiUiflora), the Wichuraiana roses (including sucli 

 esteemed varieties as Dorothy Perkins, Lady Gay, 

 and Hiawatha), and other types. Some of these are 



