July 7, 1892] 



NATURE 



221 



recent conclusions regarding the phenomena and origin 

 of volcanic action by the selection of examples drawn 

 from districts where these phenomena have been most 

 carefully observed and recorded under the light of modern 

 geological science." 



An admirable feature of the work is the recognition of 

 the principle that vulcanological problems may often be 

 better attacked by the study of ancient and greatly 

 denuded volcanoes, rather than by the examination of 

 those in actual activity, or of such as have recently 

 become extinct. 



*' Ency dope die scientifique des Aide-memoire " : — 



Resistance des materiaux. Par M. Duquesnay. 



itude experimentale calorimetrique de la machine d, 



vapeur. Par V. Dwelshauvers-Dery. 

 Air comprimd ou rar^Jie. Par Al. Gouilly. 



(Paris : Gauthier-Villars, Georges Masson.) 

 These three little hand-books on their respective 

 subjects are made by the separate publication of 

 the respective articles of the " Encyclopddie scienti- 

 fique " ; it is intended that each subject is to appear in a 

 separate volume at a rate of publication of thirty to forty 

 a year. 



There is no indication by numbering as to the order 

 of appearance, so that probably these are the pioneer 

 volumes. 



The first volume, " La resistance des matdriaux," 

 gives a very clear and concise account of the practical 

 side of Elasticity, so far as required by the engineer in the 

 design of beams, columns, bridges, and retaining walls. 



Prof. Dwelshauvers-Dery is well known for his theo- 

 retical and experimental researches on the Steam Engine, 

 and his treatise may be considered as the application of 

 the empirical laws of saturated vapours to the theoretical 

 determination of the useful effect obtainable in the 

 different forms of steam engine, simple or compound, 

 with an attempt at the evaluation of the loss due to con- 

 duction. The results arrived at are checked by com- 

 parison with long-continued steam-engine trials carried 

 out by Hirn, Donkin, Longridge, and the author himself. 



The third volume, on " Air comprimd," may be supposed 

 to carry out the same development of abstract Thermo- 

 dynamics when the medium is supposed to behave as a 

 perfect gas. In this case the mathematical laws, deve- 

 loped at the outset, are capable of more ready and imme- 

 diate application ; and the second half of the book gives 

 a detailed account of the employment of air as the medium 

 for the transmission of energy in its various industrial 

 applications— for instance, as laid on in Paris compressed 

 in mains, or as employed when rarefied in the Westing- 

 house brake. 



A useful feature in these books is a page at the outset, 

 in which the notation to be subsequently employed is 

 carefully explained. 



The Mechanical Equivalent of Heat is taken as 425 

 kilogrammetres, presumably at Paris ; the mean of Prof. 

 Rowland's experiments gives about 427 Baltimore kilo- 

 grammetres, or in absolute measure about 42 million ergs, 

 or 4*2 joules. 



The "Encyclopddie" is to be divided in interest be- 

 tween the section de VIngcnieur and the section du Bio- 

 Jogiste; the volumes promised in the first section, as in 

 course of preparation, will constitute a valuable technical 

 working library. G. 



Chambers's Encyclopcrdia. New Edition. Vol. IX. 

 (London and Edinburgh : W. and R. Chambers, 1892.) 

 The new edition of this admirable Encyclopaedia is now 

 approaching completion, and in the present volume there 

 is certainly no falling-off in the ability with which the 

 work has hitherto been written and edited. On all im- 

 portant subjects represented by words between " Round ' 

 and " Swansea " there are articles summing up the latest 



NO. I 184. VOL. 46] 



results of research. An excellent article on round towers, 

 by Dr. Joseph Anderson, is given on the first and second 

 pages. This is a model of what such a paper ought to 

 be. The author knows his subject thoroughly, and con- 

 sequently understands where to draw the line between 

 ascertained facts and the theories based upon them. 

 Another well-arranged archaeological contribution by Dr. 

 Anderson is the paper on sculptured stones. Dr. John 

 Murray writes with his usual lucidity on the sea and on 

 sounding. The task of expounding the facts and laws 

 relating to sound and to the spectrum has been intrusted 

 to Prof. Knott, and the Rev. E. B. Kirk contributes the 

 articles on the sun and the stars. Dr. Buchan is the 

 author of a clear and interesting paper on storms. 

 Other scientific articles which may be specially noted are 

 those on the Silurian system, by Prof James Geikie ; on 

 the skull, by Dr. D. Hepburn ; on the snail and the 

 slug, by Mr.T. D. A. Cockerell ; on snakes and spiders, 

 by Mr. J. A. Thomson ; on the steam-engine, by Prof 

 A. B. W. Kennedy ; and on the steam-hammer, by Prof 

 T. H. Beare. Among the geographical contributions are 

 articles on Russia, by Prince Kropotkin ; on Siam, by 

 Mr. J. S. Black ; on South Australia, by Mr. J. Bonwick ; 

 and on Spain, by the Rev. Went worth Webster. 



A Guide to Electric Lighting. By S. R. Bottone. 



(Whittaker and Co., London, 1892). 

 In this work the author gives a general idea of the 

 various methods of electric lighting, without entering into 

 any of those technicalities which tend to confuse rather 

 than enlighten the ordinary reader. Commencing with 

 descriptions of the various batteries that are now em- 

 ployed, he discusses their particular advantages and dis- 

 advantages, adding also a table of their E.M.F., currents, 

 and resistances. 



The second chapter, which is devoted to the pro- 

 duction of currents by means of the dynamo, will 

 enable the reader to form some idea as to the selec- 

 tion of one of these machines for a given purpose, and 

 to understand its general principles. Perhaps the chap- 

 ter on electric lamps and accumulators will be found 

 the most serviceable, for one is brought far more into 

 contact with them than with dynamos themselves. The 

 information here will enable anyone to set up a small 

 installation for himself, while a very useful table shows 

 the dimensions, capacities, weights, &c., of accumulators 

 suitable for such work. 



The remaining chapters deal with the descriptions of 

 some of the smaller appliances necessary in connecting 

 up the supplier of electricity, whether it be dynamo or 

 accumulator, with motors or transformers, and last but 

 not least with an excellent resume of the cost of main- 

 tenance, showing the relative prices of gas and electricity 

 as now regulated. 



The book contains numerous illustrations, and as a 

 thoroughly practical and handy work should be widely 

 read. 



LETTERS TO THE EDITOR. 



[ 7'he 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 o/" Nature. 

 No notice is taken of anonymous communications.'\ 



"The Grammar of Science." 

 To the vast majority of readers, chapter ix. of the " Grammar 

 of Science " will probably seem to be simply a plea in favour of 

 the doctrine of evolution in its purest form. We were not called 

 upon to express any opinion as to the merits of this doctrine, nor 

 did we. What struck us (and still strikes us) as fundamentally 

 illogical, was the formulation of a theory, which, itself avowedly 

 a mental product, proceeded to picture a universe devoid of 

 sentient beings, or, in the phraseology of the "Grammar, a 



