Feb. 28, 1889] 



NATURE 



411 



70,000 ; and Todd's edition of Johnson's Dictionary had 

 58,000. Even a general statement of the number of 

 headings does not give an adequate impression of the 

 amount of the contents of the present work, because, as 

 pointed out in the preface, each word has been subdivided 

 as far as possible into the various meanings which it has 

 assumed at different times. 



Judged simply as an ordinary dictionary, the work has 

 high merits. No doubt, when Dr. Murray's vast under- 

 taking is completed, both this and all other existing 

 I dictionaries will seem in many respects deficient ; but for 

 I the present we do not know that anyone wishing to 

 possess, for frequent reference, a sound, thoroughly trust- 

 . worthy dictionary, could anywhere find his want more 

 I satisfactorily supplied than in these volumes. The 

 [ question, what words can legitimately claim admission, 

 j had of course to be met at the outset, and it has been 

 I settled in a way that will commend itself to the 

 judgment of all persons competent to form an 

 opinion on the matter. All technical terms, so far as 

 known, have been included ; slang words, colloquialisms, 

 and provincialisms have not been wholly omitted ; 

 specially coined words have also, in some instances, been 

 recognized ; and due respect has been shown to semi- 

 naturalized words and to hybrid compounds. The de- 



■ partment of etymology, we need hardly say, has received 

 L much careful attention ; and great pains have been taken 



to provide quotations illustrative of every sense of each 



■ word, with references as full as could be given. The 

 pronunciation of words is clearly indicated, and the 

 adoption of various styles of type makes it easy for 

 persons using the Dictionary to distinguish between 

 various divisions and subdivisions of words. 



As the title indicates, it is not merely as a dictionary 

 that the work should be estimated. The aim has been 

 to combine the advantages of a dictionary with those 

 of an encyclopaedia, and this idea has been realized 

 with a remarkable degree of success. No one will 

 '. expect to find here, under any heading, full in- 

 formation, such as one reasonably looks for in a 

 great encyclopaedia. Nothing of this kind has been 

 attempted. But under each heading the thing is described 

 as well as the word ; and although the descriptions are 

 necessarily brief, they are, so far as they go, clear and 

 accurate, and no one who refers to them will afterwards 

 have to unlearn anything they may have taught him. The 

 short articles relating to the various branches of natural 

 science are especially well done — a fact which will be 

 readily understood when we say that the editor and 

 publishers acknowledge the services of many eminent 

 scientific workers, including Prof Huxley, Dr. Sclater, 

 Dr. Giinther, and Mr. Carruthers. 



OUR BOOK SHELF. 



Manuel Pratique de Cristalloi^raphie. G. Wyroubpff. 



(Paris : Gauthier-Villars et Fils, 1889.) 

 Many books have been written about crystallographic 

 calculation, and their size and the uninviting appearance 

 of their contents have probably created an impression 

 that there is something peculiarly difficult in the subject. 

 M. Wyrouboff's manual will not, we fear, dispel this 

 erroneous idea, for about 300 of his pages are devoted to 



1 



an exposition of the methods of calculation ; but the 

 book, being eminently practical, consists almost entirely 

 of examples, which are fully worked out by simple and 

 intelligible methods, while very little space is wasted 

 upon the geometrical principles involved. The work is 

 therefore very different in character from the geometrical 

 treatises which have frequently adorned the subject, and 

 will doubtless be of great use to the class for whom it is 

 written— namely, "those to whom crystallography is 

 only a means for the determination and description of 

 species," to whom and to all who are attempting to ac- 

 quire a practical knowledge of crystallography it may be 

 warmly recommended. We would only suggest to such 

 two words of caution : in the first place, the calculations 

 are in each case conducted in two ways, by means of plane 

 angles and solid geometry, and by means of spherical 

 trigonometry, — the former method is unnecessary and un- 

 desirable ; in the second place^ the Millerian axes and 

 notation of three indices should certainly be used in the 

 rhombohedral system in preference to the notation of 

 four axes. 



M. Wyrouboff is so well known as the author of 

 valuable contributions to the science of crystallography 

 (by which we mean the knowledge of the relation between 

 the physical, chemical, and geometrical characters of 

 crystals as distinguished from either the study of mine- 

 ralogy or the art of crystal-measurement), that the follow- 

 ing remarks, taken from his preface, deserve particular 

 attention : — 



" How far more advanced would be our knowledge of the 

 intimate structure of bodies if chemists were to describe 

 accurately the form of the innumerable substances which 

 issue from their laboratories, and which, being sometimes 

 accidentally obtained, difficult to reproduce, or prone to 

 rapid decomposition, are lost to science ; and if, on the 

 other hand, physicists were accustomed to connect the 

 properties which they discover with the symmetry which 

 belongs to the crystalline exterior. It is true that in 

 doubtful cases, or such as are of particular interest, they 

 both have willing recourse to the professional crystallo- 

 grapher ; but, apart from the fact that he is not always 

 at hand, experience teaches that such a division of labour 

 rarely gives good results. Forms placed in arbitrary 

 positions without regard to the forms of allied substances 

 often serve only to conceal the analogies which are 

 professedly sought," &c. 



From which we gather that the position of crystallo- 

 graphy in France is much the same as in England, and 

 that such books as that of M. Wyrouboff, although not 

 liable to be choked by the thorns of competition, are at 

 present somewhat likely to fall upon the stony ground 

 of indifference. 



Assistant to the Board of Trade Examinations. By 

 Captain D. Forbes, F.R.A.S. (London : Relfe Bros., 

 1888.) 

 In preparing candidates for the Board of Trade examina- 

 tions for officers' certificates, Captain Forbes has felt the 

 want of a handy book of reference to the various questions 

 asked, and he hopes to supply that want by the little 

 book before us. In these examinations, the candidate has 

 to show his knowledge by answering a number of a set 

 of questions which is the same from year to year, although 

 those selected by the examiner may be different. The 

 questions put to the candidates, and the answers to 

 them which the autiior suggests, are given in this little 

 book. As examples of brevity, the definitions given of 

 the various astronomical terms are unequalled in any 

 book we are acquainted with. Thus, right ascension is de- 

 fined as '* the distance which a heavenly body is eastward 

 of the first point of Aries"; while not the slightest idea 

 is given of the meaning of the latter term. On p. 14, 

 sidereal time is stated to begin when the first point of 

 Aries is on the meridian, and to end when it returns to it 



