504 



NATURE 



{Oct. 5, 1876 



speech to which they belong. To learn to speak a foreign 

 language by reading a grammar and writing exercises is 

 an impossibility. We must imitate the procedure of the 

 child, and be content to follow the same method in 

 learning a new language that we followed when learning 

 our own. The essence of a language is its idioms ; no 

 amount of grammatical study will teach us these. The 

 study of grammar should come after our acquisition of a 

 language, not before it. 



M. Gerard defines his method as follows : — " We must 

 accustom ourselves to the expression of ideas in the lan- 

 guage we wish to learn by comparing it with their expres- 

 sion in our own, until we are able, through imitation and 

 analogy, to express them in our own. In other words, we 

 must understand the language and think in it before we 

 use it." Understanding a language means reading and 

 hearing it ; using a language means speaking and writing 

 it. Hence the course of study recommended by M. 

 Gerard comprises the four distinct processes of reading, 

 hearing, speaking, and writing, reading coming first and 

 writing last. If reading is the primary object in learning 

 a new language, M. Gerard's course is undoubtedly the 

 right one, but if speaking is rather aimed at, we think it a 

 mistake to make reading precede. What is heard will 

 then have to be translated into the language of the eye 

 before it is understood, and this will be a serious im- 

 pediment to the learner. Moreover, a language consists 

 in the phonetic sounds by which it is conveyed, not in 

 the symbols whereby these sounds are expressed on 

 paper. • Learning to read should follow learning to speak, 

 as it does in the case of children. With this single excep- 

 tion, we can heartily endorse all M. Gerard's recommen- 

 dations ; they are founded upon nature and reason, and 

 their practical efficiency has already been proved. Espe- 

 cially noticeable are his remarks on the use of transla- 

 tions ; a dictionary is desirable only when we have ac- 

 quired a fair elementary knowledge of a language and its 

 forms of expression. Language starts with the sentence, 

 not with the isolated word. A. H. Sayce 



OUR BOOK SHELF 



The School Manual of Geology. By J. Beete Jukes, 

 M.A., F.R.S., late Director of the Geological Survey of 

 Ireland. Third Edition, revised and enlarged, edited 

 by A. J. Jukes- Browne, B.A., F.G.S. (Edinburgh : A. 

 and C. Black, 1876.) 



The late Prof. Jukes's admirable "School Manual of 

 Geology " is already so favourably known to teachers of 

 the science, for the clearness of its style, the accuracy of 

 its information, and the abundance and excellence of its 

 illustrations, that, in welcoming the appearance of a third 

 edition of the work, we shall confine ourselves to a few 

 remarks upon the changes which the editor has found 

 necessary to make in it. In doing so, we have again to 

 commend Mr. Jukes-Browne's skill in so well maintaining 

 the distinctive characters of his uncle's work, while not 

 hesitating to introduce such new matter as is demanded 

 by the progress of the science. 



In revising the chapter on igneous rocks, the editor 

 acknowledges the assistance he has received from the 

 Rev. T. G. Bonney. The principle of classification which 

 he adopts— that, namely, of grouping the rocks, not 

 according to one set of characters only, but on the basis 

 both of their mineralogical constitution and their minute 

 structure— we consider unexceptionable. To some of the 

 definitions adopted in this chapter wc must however de- 



mur, as for example to those of andesite, porphyrite, and 

 diorite, in all of which the essential felspar is stated to be 

 oliooclase. As petrographers are not in possession of any 

 ready means for determining the exact variety of felspar 

 in a rock, in the absence of a complete chemical analysis 

 of it, such a distinction becomes almost entirely useless in 

 practice. Most continental writers avoid this difficulty 

 by applying the same general terms to all such rocks as 

 are shown, by microscopic examination or otherwise, to 

 have any variety of the plagioclase felspars as their pre- 

 dominant constituent. We must also confess to grave 

 doubts as to whether the revival of the obsolete term 

 leuciliie is warranted either by necessity or convenience. 



In respect to that long-vexed question of geology, the 

 limit between the Silurian and Cambrian systems, we 

 think that Mr. Jukes-Browne has exercised a very wise 

 discretion. He has in the present edition adopted the 

 judicious compromise between the claims of Murchi- 

 son and Sedgwick, which was long ago suggested by 

 Lyell and Phillips, and has received such able sup- 

 port from the researches of Salter and Hicks. If con- 

 venience and scientific truth are not to be wholly sacri- 

 ficed to the desire to do homage to the memory of an 

 individual, it is quite time that the aggrandised empire of 

 Siluria should be resolved into its proper elements, and 

 that these should resume their due place in the brother- 

 hood of formations. 



In introducing some necessary changes into the chapter 

 on the Glacial period, the editor has wisely avoided too 

 hastily adopting any of the crude speculations which 

 have recently been advanced on the subject. The state- 

 ment, however, that the till of Scotland is of older date 

 than the boulder clay of the English Midland Counties 

 surely stands in need of some modification. 



We heartily congratulate the editor andjpublishers of 

 this very useful little manual on the well-merited success 

 which it has attained. 



Gtology: its Influence on Modern Beliefs. Being a 

 Popular Sketch of its Scientific Teachings and Eco- 

 nomic Bearings. By David Page, LL.D., F.G.S. 

 (Edinburgh and London : William Blackwood and 

 Sons, 1876.) 



Under the above title Dr. Page has published two essays 

 which are devoted to an exposition of the chief scientific 

 results, and a vindication of the economic value and im- 

 portance, of geological research. The somewhat rhetorical 

 style of these essays is sufficiently accounted for by the 

 fact that they were originally prepared by their author as 

 popular lectures for an Edinburgh audience — a disposition 

 of them which was frustrated by his ill-health. Dr. Page 

 has very effectively grouped, and eloquently sustained his 

 several theses, while many of the chief points of his dis- 

 courses are rendered more telling by admirably chosen 

 illustrations from the immediate neighbourhood of the 

 city in which the lectures were to have been delivered. In 

 one or two instances, however, we notice that the author 

 has not succeeded in avoiding the danger of making his 

 generalisations of too sweeping a character — as for 

 example when he informs us, without any qualification, 

 that " men need not search for the veined marbles of the 

 metamorphic rocks in tertiary beds, for metalliferous- 

 veins in secondary strata, nor for workable coal-seams in 

 the Old Red Sandstone and Silurian systems." 



The Law of Storms Considered Practically. By^W. H. 

 Rosser. (London : Chas. Wilson, 1876.) 



We have read this little book with very great pleasure, 

 and can strongly recommend it to the navigator as giving 

 briefly, but pleasantly and intelligently, an account of the 

 history of the law of storms, down to the present time, 

 inclusive of the various theories which have been pro- 

 pounded. The book is also to be commended as evincing 

 throughout a remarkable justness of criticism, of which 



