April 19, 1877] 



NATURE 



527 



they are in contradiction to the best experiments we have 

 on the subject (Sir William Thomson's). A teacher ought 

 to be spared as much as possible from having to tell his 

 students that he does not agree with the writer of a text- 

 book. 



The parts of Mr. Cumming's book which we have ven- 

 tured to criticise refer chiefly to matters of taste. There 

 is no doubt that in the hands of a good teacher the book 

 will prove very useful. We hope that it will have a wide 

 circulation, and that a second edition will soon enable 

 Mr, Gumming to introduce such improvements as on a 

 reperusal of his own book may occur to him. 



Arthur Schuster 



OUR BOOK SHELF 



Proceedings of the London Mathematical Society, vol. vii. 

 November, 1875, to November, 1876. (London: Messrs. 

 Hodgson and Son, Gough Square.) 



In the present volume we have about thirty communica- 

 tions made by eighteen writers. Prof. Gayley writes on 

 Three- bar Motion (ti eating the matter in a different way 

 from that in which it is handled in this same volume by 

 Mr. S. Roberts, the priority of whose results is conceded 

 by Mr. Gayley) on the Bicursal Sextic ; Prof. H. J. S. 

 Smith contributes short papers on the value of a certain 

 Arithmetical Determinant and a Note on the Theory of 

 the PelJian Equation ; Lord Rayleigh has a note on the 

 Approximate Solution of certain Potential Problems ; Mr, 

 Spottiswoode writes on Determinants of Alternate Num- 

 bers, working out some suggestions of Prof. Glifford. This 

 last-named gentleman contributts the transformation of 

 Elliptic Functions with a Note, and Free Motion under 

 no Forces of a Rigid System in an ;^fold Homaloid. 



In Analysis, there are further papers by Mr. J. W. L, 

 Glaisheron an Elliptic Function identity, and the Sum- 

 mation of the Geometrical Series of the «th Order as a 

 Definite Integral ; Prof. Lloyd Tanner on the Solution 

 of Gertain Partial Differential Equations of the Second 

 Order (two papers) ; Mr. J. Hammond on the Relation 

 between Bernouilli's Numbers and the Binomial Goeffi- 

 cients, and on the Mean of the Products of the Different 

 Terms of a Series ; Mr. T, Muir on the Transformation 

 of Gauss's Hypergeometric Series into a Gontinued 

 Fraction ; Mr. S. Roberts a Further Note on the Motion 

 of a Plane under Gertain Gonditions ; Mr. Hewitt on a 

 Theorem of Eisenstein's. 



Under the heading of Geometry we may class Prof. 

 Rudolf Sturm's paper on Gorrelative Pencils ; Mr, A, B. 

 Kempe's General Method of describing Plane Gurves of 

 the «th Degree by Linkwork ; Prof. Wolstenholme's 

 Loci Gonnected with the Rectangular Hyperbola. 



There are a few shorter communications. We have 

 said enough to give our mathematical readers an idea of 

 the range of subjects treated in this volume. The names 

 of the authors are a sufticient guarantee that the subjects 

 are ably treated and brought down to the latest accepted 

 results, 



A Primer of Chemistry, including Analysis. By Arthur 

 Vacher. (London : J. and A. Ghurchill, 1877.) 



This little book attempts to present within the limits of 

 a hundred pages " a general view of the elements of inor- 

 ganic ctitmibtry." It embodies the experience gained by 

 the author during ten years in which he has been engaged 

 in teaching the subject, and the result is that many points 

 are treated in somewhat novel fashion. The subject is 

 considered as fully as could be expected within the narrow 

 limits mentioned, and the amount of information con- 

 veyed is really considerable and generally accurate. 

 The first sixty-seven pages contain chapters on " Ex- 



periments with some of the Elements," "The Use of 

 Symbols " in formulae, equations, and calculations, " Ex- 

 periments with some Gompounds," " Weights and Mea- 

 sures," " Glassification of Gompounds," and "List of 

 Substances.' The remaining thirty pages or so are 

 devoted to Qualitative Analysis. 



Perhaps the greatest novelty introduced is the use of 

 the term unit instead of atomic or combining weight, so 

 as to avoid using the terms atom and molecule, which the 

 author thinks are "unsuitable for ordinary use among 

 beginners ; " and of antimctal instead of radicle (which 

 latter by the way he incorrectly writes "radical"). It 

 may be questioned whether the use of the term " unit " 

 may not interfere with the conception of the meanings to 

 be attached to " atom " and " molecule," which the pupil 

 must gain afterwards. " Antimetal " is objectionable 

 since all radicles are not antimetals ; ammonium, for 

 example, is a radicle which plays the part of a metal. 

 Glearly the term is intended as equivalent to "acid 

 radicle," or acid minus its basic hydrogen ; it is never 

 used in any other sense in the book, and its use with this 

 restricted meaning may be advantageous, or at least free 

 from objection. 



Several items may be pointed out as requiring altera- 

 tion or improvement; notably the following: that "a 

 compound^ is any substance which is not an element" 

 (p. 11) ; that chlorine has a '■'■ pale green colour" (pp. 6 

 and 6x) ; that oxygen is insoluble in water (pp, 39 and 

 56) ; and that KMnO^ gives a red solution (p. 64}. In 

 working with test-tubes the student is several times 

 directed to add " half an inch" of acid or water as the 

 case may be. Of course it is evident what is meant, but 

 test-tubes are of various sizes, and a large excess of acid 

 or other liquid would be used if the directions were fol- 

 lowed exactly with large tubes. On p. ']'j, " take the 

 charcoal quickly to your nose " is another rather curious 

 direction. 



The analytical part of the book is the best ; the tables 

 throughout being reliable. The detection and separation 

 of cobalt and nickel (Table III., p. 95) might be effected 

 more quickly and easily by other methods than that 

 given ; and on p. 87, NO3 as well as Gr04 and Fe'" should 

 be mentioned as decomposing HjS. If these and several 

 other minor improvements be made the "primer" will 

 not be without value in imparting the rudiments of educa- 

 tion in chemistry ; and in these days when elementary 

 text-books are becoming so numerous, may fairly count 

 on being appreciated as it deserves by the class of students 

 for whom it is intended. W. H. W. 



LETTERS TO THE EDITOR 



[T/ie Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond v/ith the writers of, rejected manuscripts. 

 No notice is taken of anonymous commutncations.\ 



Hibernation of Birds 



In Nature (vol. xv., p. 465) there is a review of " Palmtn on 

 the Migration of Birds," and in the course of it the reviewer takes 

 occasion to refer to what he calls the "hibernation mania " as 

 one that is now and again revived, in spite of the fact that the 

 migration of birds is fully proved, and that no evidence at first 

 hand has ever been produced in favour of the supposition that 

 birds ever lie dormant. 



Having frequently heard my brother-in-law, Sir John 

 McNeill, relate a circumstance which occurred to himself proving 

 that swallows do occasionally lie dormant, I wrote to him asking 

 him for the particulars. I now inclose his reply, which perhaps 

 you will publish, as it may possibly ehcit other evidence on the 

 same matter. 



Gilbert White's conviction that swallows do occasionally lie 

 dormant in this country, was mainly founded on the fact that 

 instances are not uncommon of swallows appearing suddenly 



' A fAcw?V(r/ compound being meant as is evident from the context. 



