NA TURE 



25 



THURSDAY, MAY 11, 1893. 



A BOOK ON PHYSIOGRAPHY. 



" A. E. Brehm. Les Merveilles de la Nature." La Terre, 

 les Mers, et les Continents ; Geographic Physique, 

 Geologic et MinSralogie. Par Fernand Priem. (Paris: 

 J. B. Bailliere et Fils, 1892.) 



THE wonders of nature ! The book would be 

 worth having that would help us to realise, 

 however imperfectly, what it is that underlies this 

 hackneyed phrase. But the book that shall create and 

 satisfy a craving for this result will not be easy to build 

 up. It must be encyclopaedic, but (need it be said?) 

 not an encyclopaedia. It must be accurate to the 

 last degree of accuracy, but must have nothing of 

 the pedant about it. Human interests must, wherever 

 an opportunity offers, be interwoven with its narra- 

 tive. The narrative itself must be, not the heavy 

 didactic prosing of an old-fashioned schoolmaster, but 

 the congenial living talk of a friend. Sound judgment 

 must pick out what is to be told and what left unsaid. 

 So far from looking upon all facts as of equal value, the 

 utmost care must be exercised to present those only which 

 are within the grasp of the lay mind ; all that has signifi- 

 cance for the specialist only will be out of place. Nothing 

 will be inserted merely because it is curious or marvel- 

 lous, for the object will be not to make the reader gape 

 like an astonished clown at something which looks very 

 extraordinary because he does not understand it ; rather 

 to use the emotion of wonder as a means to something 

 beyond, as an inducement to look below the surface and 

 find out how results so startling have been brought about. 

 The right book must be neither shallow nor deep ; fas- 

 cinating as a poem, but sound as a scientific treatise ; and 

 it will be well if there run through all of it some one 

 leading idea, which will serve to give it unity and string 

 together into a connected whole the sections of which it is 

 made up. 



Under the title of "Les Merveilles de la Nature" a 

 series of works is being published which seem to be 

 intended for what is usually known as the "general 

 reader.'' The preceding volumes have dealt with animal 

 life, the volume now before us is devoted to Erdkunde. 

 It will be possible, without pretending to deal with the 

 whole of the bulky volume, to inquire how far it appears 

 likely to meet the requirements of those readers for 

 whom it seems intended. The work opens with " Donnees 

 gt^nerales de la Gdologie," and the commencement is 

 promising ; the treatment is broad, and illustrations are 

 supplied of the general truths enunciated. But already, on 

 p. 5) we see how little judgment has been exercised in the 

 selection of materials. Of what interest or of what 

 educational value to the general reader can be such 

 technical details as a description of the way of measure- 

 ing dip and strike in the field, and a figure of a pocket 

 compass t A few pages further on we have a com- 

 pressed summary of the succession and life of the main 

 geological epochs, and some well-executed figures of 

 their fossils. The account is far too meagre to be of any 

 real use, and it is difficult to see what principle has 

 guided the selection of the fossils. There is a "casual- 

 NO. 1228, VOL. 48] 



ness " too about some statements calculated to mislead ; 

 as when we find no mention of Brachiopods in the 

 Silurian and Carboniferous, but the emphatic assertion 

 that the Devonian fauna is specially characterised by the 

 presence of numerous Brachiopods. Again it is true 

 enough that the Triassic fauna " difffere notablement de 

 la fauna paleozoique ; " but the fact that it contains a 

 mixture of palaeozoic and mesozoic forms is at least of 

 equal importance. These instances, picked at random, 

 show how much of a compilation and how little of a 

 masterly abstract is offered to the reader. A history of the 

 progress of geology is one of those things specially 

 suited to such a work as the present. We have one here 

 interestingly written, though perhaps the salient points 

 do not stand out as boldly as could be wished. 



Further on, under the heads of mineralogy and 

 petrology, we have a vast array of facts of very unequal 

 interest or value for ordinary readers. What good can 

 it be to any one to be told that there are six or seven 

 systems of crystallisation, when he is never told what is 

 meant by a "system".' Symmetry, which lies at 

 the base of crystallographic classification, is barely 

 mentioned, and most imperfectly explained. But 

 what an attractive and instructive story may be 

 made about crystals ! Some of the more elementary facts 

 about their symmetry and probable molecular structure 

 are not hard to grasp, and furnish fascinating illustrations 

 of law and harmony. Looked at in this light, these 

 flowers of the inorganic world cease to be mere glittering 

 gauds, and tell a tale that all would follow with delight. 

 Out of Ruskin, checked by Miller, such might be con- 

 structed in place of this dull assemblage of barren and im- 

 perfectly explained facts. When' we come to the micro- 

 scopic examination of rocks there is much that is too 

 detailed for the general public and not full enough for the 

 specialist. 



The nationality of the book must be the excuse for the 

 survival of such statements as the following : — " Le 

 granite est la roche eruptive la plus ancienne. . . . 

 Ses Eruptions se sont faites pour la plupart avant le ddpot 

 des roches scdementaires : le plus rdcentes paraissent 

 dater du cambrien." " Les porphyres p^trosiliceuse sont 

 charactdristiques de I'cpoque permienne." But surely any 

 one whose knowledge went beyond a few books would 

 have thought it fair to say that these views were not 

 universally adopted, though they are held by some of the 

 most distinguished of his countrymen. 



Turning to other branches of knowledge, the critic is 

 still compelled to take serious objection to much that he 

 meets with. Solar and stellar physics are scarcely up 

 to date, though perhaps there is enough for a book of this 

 class. It will be hard for any one who depends upon this 

 book alone to gather how the shape of the earth is ascer- 

 tained. It is all very well to copy out of a book that an 

 arc of 1° is so long in Peru and so long in Lapland, but 

 there is no word said as to how astronomers find out 

 that they have travelled over 1° of latitude, nor of the 

 trigonometrical survey requisite to measure the length of 

 the arc. These points are easy enough of explanation, 

 and if in place of the misleading cut on Fig. 64 a figure 

 had been given with the necessary explanation, we should 

 have had something of educational value instead of a 

 mere transcript. Statements are made with great con- 



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