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NATURE 



[Oct. 31, 1878 



themselves to such an abstract of miscellaneous informa- 

 tion as may be of service to the ordinary reader. No 

 article is admitted which requires for its comprehension 

 either special preparation or special application. The 

 " Encyclopaedia Britannica " aims at something more than 

 this ; it addresses itself to the general readers, but it also 

 has a real value for students. On this large plan it 

 becomes very difficult to adjust the respective claims of 

 the two classes to whom the work appeals, and the 

 practical solution must probably be to give what is likely 

 to attract purchasers of a special class without repelling 

 the general public in larger numbers. This seems to be 

 what Prof. Baynes has in view when, along with such 

 articles of general interest as Mr. Freeman and Mr. 

 Gardiner's England, he gives us on the one hand an 

 abstruse essay on Elasticity, bristling with mathe- 

 matical formulae, and on the other a selection of hints for 

 success in playing Euchre. 



The chief difficulty in successfully carrying out so large 

 a plan lies in the scientific monographs, and more 

 especially in the treatises on subjects which cannot be 

 thoroughly handled without mathematics. In the ninth 

 edition these articles are of a very high class. The editor 

 must be congratulated who, within the two volumes now 

 before us, has articles by Prof. Clerk Maxwell on Dia- 

 grams, Diffusion, and Ether, by Sir W. Thomson, 

 on Elasticity, by Prof. Cayley on Equation, and by 

 Prof. Chrystal on Electricity. All these are admirable 

 pieces of scientific writing of different kinds. The article 

 Electricity is a singularly clear and well-arranged expo- 

 sition, which, if printed as a separate volume, would form 

 the best possible text-book for students who are well 

 advanced in pure mathematics. On the other hand 

 Prof. Cayley' s account of Determinants and the Theory 

 of Equations is not of the nature of a text-book, but can 

 be appreciated only by those who have some knowledge 

 of the subject. Prof. Maxwell's papers, full of his usual 

 quaint illustration and felicitous turns of expression, 

 sometimes amounting to scientific epigram, would be 

 perfect encyclopaedia articles if the ordinary reader 

 possessed accurate habits of thought on physical subjects 

 -h'ithout actual physical knowledge. But in the present 

 condition of things they are most likely to serve an oppo- 

 site purpose in clarifying the thoughts of those who have 

 already some reading on the topics dealt with. All these 

 papers suggest the question whether an Encyclopaedia of 

 general information ought not to limit itself to articles 

 which can be followed by a painstaking reader who has 

 no other preparation or assistance than he can find in the 

 Encyclopaedia itself. Yet, on the other hand, we are 

 grateful to the editor who has opened his pages to so 

 - much valuable writing which otherwise might never have 

 appeared at all. 



In passing from this topic we may notice, in the article 

 IEnergy, a curious over-statement of the inference to be 

 drawn from the ingenious speculation associated with 

 what are called Prof. Maxwell's "demons." We are 

 told by Mr. Garnett that this speculation "shows that the 

 principle of dissipation of energy has control over the 

 actions of those agents only whose faculties are too gross 

 to enable them to grapple with those portions of matter in 

 virtue of the relative motions or relative positions of 

 which the energy exists with which they are concerned." 



Mr, Garnett has forgotten the trap-doors which the hypo- 

 thetical demons command. In fact the simplest form of 

 the hypothesis would be to drop the demons, and make 

 the trap-doors themselves intelligent beings, possessing 

 resistance, and capable of moving without expenditure of 

 energy. Such beings would not be controlled by the law 

 of dissipation, but they would differ from all agents 

 known to observation in a more essential point than the 

 possession of subtler faculties. 



Passing over less abstruse branches of science, which 

 are well represented in these volumes by Prof. Huxley, 

 Mr. Wallace, Prof. McKendrick, and other names of 

 mark, we must devote a few sentences to the articles 

 which deal with the history of human life and the move- 

 ments of human thought. A valuable feature in the 

 editor's plan is the prominence giren to subjects con- 

 nected with the ideas, habits, and traditions of primitive 

 man. In this line we have an excellent article on Deluge, 

 by Mr. Cheyne, and a very interesting paper on Demono- 

 logy, by Mr. E. B. Tylor. Some of the facts adduced 

 in the latter article may probably need further sifting. 

 We do not think so highly as Mr. Tylor does of Maury's 

 book on magic. Lenormant's work on Chaldean magic 

 must be used with reserve, and, to mention but one other 

 point, the theory of a schism between Indians and 

 Iranians, connected with a change in the meaning of 

 the word deva, is open to grave objections. Among 

 properly philosophic papers Mr. Sully's Evolution is 

 valuable from its comprehensive survey of the history of 

 the subject, while Mr. Sidgwick's sketch of the progress 

 of ethical speculation, which may be said to replace Sir J. 

 Mackintosh's dissertation, written for the seventh edition 

 of the " Encyclopaedia," gives striking proof of the real 

 advances that are being made in what is often re- 

 garded as the most stationary department of human 

 thought. 



The articles in Geography, History, and Biography, 

 which to the general reader form the most valuable part 

 of a book of reference, are as a rule very good. Subjects 

 of special importance or attractiveness are treated in these 

 as in the previous volumes by writers of distinguished 

 position and special information, while the minor articles 

 speak well for the diligence and scholarship of the per- 

 manent staff. In a few cases material taken over from 

 the last edition might with advantage have been more 

 strictly revised. In conclusion, we would offer one or 

 two hints for this part of the work. It is very desirable 

 that bibliographical references should be as complete and 

 uniform as possible. At present there is considerable 

 inequality in this respect, both as regards the statement 

 of sources of information, and the enumeration in the 

 biographical articles of authors' works and their editions. 

 In such an article as that on Dictionary it would 

 be unfair to expect completeness or absolute freedom 

 from error, and one does not complain of such a slip as 

 the reference to Rabbi lona ibu Ganach's Lexicon as still 

 unpublished, when in reality it has been edited by Neu- 

 bauer. But an enumeration of modern books upon 

 Ethiopic ought not to have omitted Dillmann's Grammar 

 and Lexicon, and an article on Ephesians is not com- 

 plete without reference to Holtzmann. 



There is one other point which a reviewer ought not to 

 pass over. In every encyclopaedia there must be a certain 



