Feb. 





NATURE 



in rolling aside as far as he can the obstacles that lie so 

 thick on the path, and, when he cannot clear them away, 

 in helping the novice with tender, loving hand to surmount 

 them, and the wish that lies nearest to his heart is to 

 make the journey as smooth and easy as is compatible 

 with thoroughness, It can scarcely admit of a doubt that 

 the way to do this is to begin with the simple, the known, 

 and the certain, and gradually lead on to the complicated, 

 the doubtful, and the hypothetical. And it is not only 

 because it smooths the beginner's path that this is the 

 more excellent way, it is even more than that, because it 

 engenders from the outset a habit of clearly distinguishing 

 between what we may fairly look upon as established 

 truths and the things which are still matter of speculation. 

 If hypotheses are forced on the student's attention in the 

 early part of his career, and still more if these hypotheses 

 are spoken of as if they were universally-accepted doc- 

 trines, the learner soon ceases to distinguish between fact 

 and theory, and his scientific studies lead only to con- 

 fusion of thought and a habit of jumping to conclusions 

 from imperfect data. 



It is for these reasons that I cannot help doubting the 

 wisdom of introducing so early as the second chapter 

 questions about which so very little is known for certain 

 as the composition and condition of the earth's interior, 

 the origin of the earth's figure, and the nebular or 

 meteoric origin of the earth itself. The author is, how- 

 ever, countenanced in this by the practice of many eminent 

 geologists, and I will not therefore press the objection ; 

 but I feel little doubt that he has not acted in the best 

 way for the interests of those for whom he seems to have 

 written when, only two chapters further on, he plunges into 

 the vexed question of the origin of the crystalline schists. 

 Chapter IV., which deals with this matter, begins, " The 

 newest water-formed rocks are similar in appearance to 

 deposits which are now being deposited." Xot a word 

 has yet been said about the class of rocks described as 

 water-formed, nor any reason given why they are believed 

 to have been formed in water. Why should this be taken 

 i mted when it is a matter so easy to understand and 

 about which there is so little difference of opinion ? 

 Surely it would have been safer for a beginner to make 

 the demonstration of a proposition so simple as this his 

 introduction to the study of geology, than to launch him 

 at the outset on a sea of speculation when he is tossed to 

 and fro by conflicting theories and bewildered by the 

 opposite opinions which different authorities hold. Our 

 author, it is true, evades this danger, but he does it in a 

 way that is distinctly unfair to his readers. He shows 

 that it is not impossible that crystalline schists may be 

 produced by the metamorphism of sedimentary deposits, 

 and then lays it down, without any further reason, that all 

 rocks of this class have been produced in this way, but 

 he says nothing to lead us to suspect that this is at best 

 an hypothesis, still less that it is an hypothesis which 

 many geologists decline to accept. This looks very much 

 like one of those sweet and easy ways which are so 

 severely denounced in the preface. Nor is his further 

 development of the subject any less unsatisfactory. He 

 gives one of the many reasons that have been alleged in 

 favour of the view that granite is also a product of meta- 

 morphism ; goes on to the further step that granitic rocks 

 are the deep-seated forms of lavas, and so leads up to 



the conclusion that all crystalline rocks are metamorphic 

 products. There are many geologists, myself for one, 

 who look favourably on this speculation, who are even 

 sanguine enough to believe that the day will come when 

 it will be placed among established facts, but I could 

 hardly have thought it possible that any scientific writer 

 could have stated it in the present day as a thing about 

 which there was no question ; and it scarcely seems 

 prudent, when geology offers us so much that is sure and 

 certain on which to base our teaching, to choose one of 

 the most speculative of its tenets as the foundation for a 

 scheme of instruction. 



A chapter follows on the " Nature, Composition, and 

 Origin of the Water-formed Rocks," which illustrates 

 under a typical form the defects and excellences of the 

 greater part of the book. There is much admirable matter 

 and the illustrations are well chosen, but it would be very 

 hard to teach from this chapter. The facts are all strung 

 together in a continuous narrative, somewhat scattered, 

 too, so that if we wished to make out all the steps in the 

 formation of a certain rock, say an organic limestone, we 

 should have to pick out a clause here and a sentence 

 there and piece these fragments together. In fact, this 

 and many other parts of the book remind us of a forma- 

 tion rich in organic remains, but requiring much labour 

 to unravel because the fossils are embedded in rock, are 

 mixed confusedly together, and are, many of them, frag- 

 mentary. We do not put a beginner in palaeontology to 

 work on such a deposit, but let him first get systematic 

 knowledge in a museum where the fossils have been 

 extracted and set up in order. And it is just such orderly 

 arrangement of the facts and the deductions that follow 

 from them which is wanted in a scientific manual intended 

 for a beginner ; they ought not to be embedded in the text, 

 where they have to be hunted for, but they want picking 

 out and placing each by itself in a strong light so that 

 they may catch the eye of the student. Again, if we 

 remember that the materials out of which the water-formed 

 rocks are built up were furnished by denudation, it would 

 seem that an account of the origin of these rocks must 

 necessarily begin with a description of the mode of action 

 and products of denuding agents, but for this we have 

 to wait till we reach Chapter XI. That chapter and 

 Chapter X. furnish one of the most perfect instances of 

 the " cart before the horse " to be met with anywhere. 

 Chapter X. is headed " The General Features of the 

 Scenery in their Relation to Geological Phenomena " ; in 

 it, while due weight is given to the influence of upheaval in 

 determining the shape of surface, the large share which 

 denudation has played in forming hill and valley is fully 

 recognised ; but it is not till we come to the following 

 chapter that we are told what denudation is and how it 

 works. 



The author may say, however, that all this is very much 

 matter of opinion, that I have my notions as to the way 

 in which geology is to be taught and the order in which 

 its subject-matter is to be presented, and that he has his. 

 It may be so, but there are in the book slips and errors 

 about which there can be no difference of opinion, and to 

 which I feel sure the author himself will be glad to have 

 his attention called. We do not generally describe char- 

 coal as uncrystallised diamond, but this would be nearly 

 as bad as "calcite in an uncrystallised condition " (p. 47) ; 



