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NATURE 



{Nov. 28, 1889 



is to be of any value for mental discipline, must lead up 

 from the simple to the complex, from the particular and 

 concrete to the general and abstract. To start with the 

 nebular hypothesis in geology may claim to be taking 

 things in their historical order, but is like giving meat to 

 a baby of three months old. To lay before the beginner 

 a familiar object such as a lump of sandstone or lime- 

 stone ; to show him how to pull it to pieces and find what 

 it is made of ; to give him reasons for the belief that it has 

 not existed from the beginning of all things, but is a 

 naturally manufactured product; to drive him to rummage 

 brook, river, pond, and sea, the whole field of outdoor 

 nature, in hopes of finding some similar product now in 

 process of manufacture, — some such treatment as this at 

 the outset would seem to be the way to lead a beginner on 

 to use his hands, his eyes, and his reasoning faculties — in 

 a word, to educate him. And at this stage only well 

 ascertained facts, and conclusions on the soundness of 

 which no doubt can be thrown, ought to be introduced ; 

 incomplete observations and experiments, inferences which 

 are no more than likely, all provisional and speculative 

 hypotheses, and all controversial matters, ought to be 

 kept carefully in the background. We do not trust a 

 youngster among quicksands and shaking bogs till much 

 walking over sound ground has given him sturdy legs, 

 sure feet, a quick eye, and sound judgment. There is a 

 bit of advice given in the preface to the book now before 

 us, which is not likely to do much harm because it 

 certainly will not be followed by those for whom the book 

 is written ; but one shudders to think of the mental chaos 

 that would result from reading every book or article on 

 geology which can be bought or borrowed, the contro- 

 versy on the Taconic System included. To encourage so 

 omnivorous an appetite is not according to knowledge. 



The limits of an article will not allow of more than the 

 fringe of the subject being just touched upon ; but enough 

 has been said to show what seem to be the things to be 

 striven after and the things to be avoided in a book on 

 elementary science which aims to educate its readers. 



The other kind of text-book is necessarily constructed 

 on a totally different principle. The author's aim is to 

 satisfy the requirements of a syllabus or code ; lucky it is 

 if he is a slave to only one, and does not vainly struggle 

 to meet the demands of many. The reader must be 

 fortified against every possible form of question which the 

 ingenuity of the examiner can devise without going out- 

 side the prescribed limits ; and as that ingenuity is 

 boundless, the number of such questions must be legion. 

 Hence arises the necessity of packing into a small com- 

 pass an endless variety of subjects, with the result that 

 only a few words can be spared for each. Each also, 

 instead of standing out crisp and sharp with an appro- 

 priate heading to call attention to it and emphasize its 

 importance, shares with two or three others, with which it 

 may have only a remote connection, the cramped quarters 

 of a single sentence. What a risk there must be in such 

 a case that matters of great moment may be passed by 

 unheeded ! Even in a crowd we may stumble on inter- 

 esting folk, but it is not in a crowd that intimate acquain- 

 tance or lasting friendships usually begin. 



There is another evil in books of this kind ; they foster 

 the dangerous belief that there are short cuts to learning— 

 a notion welcome enough in this age of hurry and unrest, 



when everything is to be done quickly, well also if you 

 can, but quickly at any cost. 



An amusing illustration of the educational value of the 

 ordinary text-book may perhaps be allowed a place here. A 

 girl, sharp enough to be worth taking pains with, came to 

 me for assistance in the preparation for her examination. 

 She was happy in the possession of a text-book which 

 professed to give all the information which her syllabus 

 required on I know not how many branches of science. 

 She was just beginning the section on chemistry and was 

 much exercised as to the meaning of chemical symbols. 

 I was able to remove her difficulties, and to send her away 

 hopeful that further progress would be easy and rapid. 

 The latter it certainly was, for at the end of a week she 

 came again with a beaming face ; she had finished 

 chemistry, and made some way in meteorology, I natur- 

 ally demurred to her getting her geology in this fashion, 

 and substituted for the geological section of her book a 

 well-known primer. She repaid me and showed her 

 appreciation of what scientific writing ought to be, by 

 declaring that this was as good as a story-book. 



But it would not be fair to take the precious compendium 

 from which, but for a lucky accident, this girl would have 

 derived all her knowledge of science, as a fair sample of 

 the average text-book. On many even of the second 

 class it is possible to look with qualified satisfaction, and, 

 though the work before us must be placed in this class, 

 it is good of its kind. There is life and spirit in it, and 

 here and there its points are happily put. No one who 

 reads it attentively can fail to get from it information 

 which not only will be serviceable in examinations, but 

 may be used as a stepping-stone to further progress in its 

 subject. But I should like to call the attention of the 

 author to a few points in which there seems to be room 

 for improvement. 



The exigencies of space demand that there should be no 

 repetition in a book of this kind. But there is more than 

 one case in which our author says over again what has been 

 already said on a previous page. For instance, on pp. 71 

 and 72 we have much that has been previously given in 

 chapter ii. The amount of dissolved matter in the Thames 

 is stated twice over, on p. 1 1 and again on p. 73. Other 

 cases might be quoted. The general arrangement of 

 chapter viii. does not seem to be commendable : it is hard 

 to see why such simple matters as ripple-marks, rain- 

 pittings, and sun-cracks should come after the more com- 

 plicated structures of foliation and faulting ; what would 

 seem the natural arrangement, of beginning with the 

 simple, is absolutely reversed. The term current-bedding 

 is used and partially explained on p. 22, but we do not 

 find a full definition till p. 45. 



A few cases of incomplete information and even of 

 looseness of statement may be noted. In speaking of the 

 consolidation of sediment by pressure, only the weight of 

 the overlying rock is mentioned on p. 18. Whether glaciers 

 move solely by the force of gravity, as is implied on p. 76, 

 is to say the least a moot point. The description of 

 fire-clay as " a fairly pure variety of clay, contmmng but 

 little water j'' can hardly be said either to be accurate or 

 complete. Marl is not clay mixed with li?ne. It is 

 surprising to find among so many really good illustrations 

 the time-honoured section across the Jura on p. 42, which 

 only deserves to be preserved as about the most successful 



