534 



NA TURE 



[April" 7; 1898 



From the general subject of Canadian mineral re- 

 sources, and the. need for their development, Prof 

 Roberts-Austen passes to a particular metal — nickel. 

 The splash of a falling marble which is dropped into 

 milk, and of a gold bullet dropping into molten gold, is 

 shown, by means of reproductions of photographs, to 

 bear a resemblance to the splash produced upon armour 

 plates by projectiles. To prevent the marble from enter- 

 ing the milk, the surface of the liquid might be hardened 

 by freezing it. Using this illustration. Prof. Roberts- 

 Austen ingeniously explains that in a similar way an 

 armour plate should have a face of rigid steel to 

 break up a projectile, and a tough back to save the 

 plate from fracture. These conditions are obtained by 

 the addition of 4 or 5 per cent, of nickel to steel. 



There are many curious points connected with the 

 relations of iron and nickel, and several of scientific 

 interest are described in the present volume. Every one 

 interested in the properties of metals, or desirous of 

 obtaining a concise and trustworthy account of Canada's 

 mineral riches, should read what Prof. Roberts-Austen 

 has to say upon these subjects. 



Hann, Hochsietter^ Pokorny — Allgemeine Erdkunde, 

 Fiinfte, neu-bearbeiiete Aiiflage. II. Abtheilur.g : 

 Die feste Erdrinde und ihre Formen. Von Ed. 

 Bruckner. Pp. xii -f 368. (Wien : F. Tempsky, 

 if "~ 



In undertaking to produce a new edition of Hochstetter's 

 share in the Allgemeine Erdkunde^ Prof Bruckner very 

 wisely determined to rewrite the whole section, and so to 

 bring it into line with contemporary methods and results. 

 The scope of this treatise on the crust of the earth and 

 its forms includes a sketch of petrography, geological 

 structure, stratigraphy, the agencies which work on the 

 earth's surface (classed as endogenous and exogenous), 

 the forms of the crust, and the morphology of the land- 

 surface. 



Prof. Bruckner follows Richthofen and Penck for the 

 most part ; but his range is wide, and he pays due regard 

 to the work of British and American geologists. It is 

 particularly noteworthy that an authority who knows the 

 Alps so well should refrain from making them the main 

 source of his illustrative examples. In speaking of the 

 interior of the earth the author leans to the view of the 

 central part being in a gaseous state, the gaseous rock 

 being reduced by intense pressure to a higher density than 

 any liquid known on the surface ; but he quotes and very 

 impartially discusses the more generally accepted view of 

 a solid earth due to the raised melting-point of rocks under 

 pressure. Earthquakes are treated at some length ; but 

 the work of Milne is not referred to, Rebeur-Paschwitz 

 being the principal modern authority cited. In dis- 

 cussing the origin of land-forms, more weight is given 

 than in most text-books with which we are familiar to 

 the importance of tilted or vertically displaced blocks of 

 crust, and relatively less importance is attributed to 

 folded structures. In treating of the regime of rivers 

 and the classification of land-forms, Prof. Bruckner 

 follows Penck closely. 



A number of useful references are given to special 

 works treating on the special departments under notice ; 

 and it is gratifying to find a fair proportion of English 

 books amongst those cited. In speaking of caverns, 

 however, the author fails to mention M. Martel's 

 important researches, or to refer to the Speleological 

 Society. The revision of the work is very thorough ; the 

 only serious misprint of proper names we have noticed 

 is the citation of the author of the Mundus Subterraneus 

 as " Kirchner " in place of " Kircher." 



This important work, so well-written by a master of, 

 his subject, is simply one amongst many German books 

 on physical geography, a class still very poorly repre- 

 sented in the English language. H. R. M. 



NO. 1484. VOL. 57] 



Elementary yBotany, By Percy Groom, M.A., F.L.S. 



Pp: X -I- 252. (London : G, Bell and Sons, 1898.) 

 In his preface the author explains that his object has- 

 been "to place the subject before elementary students 

 in such a way as to exercise to the full their powers of 

 observation, and to enable them to make accurate 

 deductions for themselves from the facts which they 

 observe." The book is written on the assumption that a 

 compound microscope is not employed ; and in the 

 section on physiology no knowledge of the histology 

 of plants is assumed. There are already numerous 

 books more or less suitable as guides to the student 

 of elementary botany, some of them so excellent as to- 

 leave little, if anything, to be desired in their special 

 fields. But they either omit a good deal that might 

 readily enough be examined and verified even by 

 beginners, or they require such a use of the compound 

 microscope as is scarcely practicable in the teaching of 

 botany in schools. A book on the lines indicated by 

 Mr. Groom should prove very helpful alike to beginners 

 and to teachers, and would doubtless be welcomed if felt 

 to be the result of adequate personal experience. But 

 we cannot altogether congratulate the author on his- 

 success in carrying out his objects, despite the merits- 

 of his work, especiall) if it is intended as a school-book^ 

 Children can scarcely be expected to benefit as much 

 from the study of general morphology as from the 

 examination of selected plants, in which they could 

 observe and gradually become familiar with the various- 

 structures and life-histories. 



The definitions of terms are at times scarcely in keep- 

 ing with general usage ; for example, those of compound 

 leaves, cestivation and vernation, and compound fruits; 

 It may be questioned whether the statement — " that 

 portion of a single flower which persists after fertilisation 

 until the seeds are ripe is termed the fruit " — is preferable 

 to the usual definition. The classification of fruits also 

 is unsatisfactory. 



Such a statement as that "a root can only produce as 

 lateral members branches like itself" is misleading, and 

 indicates want of care. The production of buds by roots 

 can easily be verified ; indeed, the author refers to their 

 growth on roots under " adventitious shoots." 



In the physiology a knowledge of chemistry is assumed 

 to an extent beyond what is to be looked for in many 

 schools. In consequence a good deal of this section 

 could be little more than words to those for whom the 

 book seems to be intended. The plants treated of all 

 belong to the flowering plants, though there seems no 

 good reason why representatives of the larger cryptogams 

 should not find a place in such a work. But the task of 

 a censor is unpleasant ; and although it has been 

 necessary to criticise what must impair the usefulness of 

 the book, we gladly recognise that it should often be 

 found suggestive by teachers and others possessed of 

 sufficient knowledge to avoid being misled where the 

 risk exists. The book is well printed, and is of very 

 convenient size, and the illustrations are good and 

 numerous ; but it would have made them more useful 

 had some of them been repeated where more than once 

 particularly referred to and explained. References to 

 figures, sometimes many pages back, are apt to be 

 irritating. 



Alembic Club Reprints. No. 13. The Early History of 

 Chlorine. No. 14. Researches on Molecular Asymmetry. 

 Pp. 46 and 48. (Edinburgh : W. F. Clay, 1897.) 

 The first of these reprints contains translations of papers 

 by Carl Wilhelm Scheele (1774), C. L. Berthollet (1785), 

 Guyton de Morveau (1787), and J. L. Gay-Lussac and 

 L. J. Thenard (1809). This volume, together with the 

 earlier reprint in this series (No. 9), containing Davy's 

 researches, completes the history of chlorine from its dis- 

 covery by Scheele to the proof of its elementary nature 

 by Davy. The importance of this discussion upon the 



