702 



NATURE 



[February 24, 19 16 



Some familiar terms are used in a sense that 

 is not likely to find favour on this side the 

 Atlantic. Take, for instance, the following- on 

 p. 108 : " Extreme induration and recrystallisa- 

 tion of a shale, independent of dynamic action or 

 contact-metamorphism, may produce a highly 

 crystalline rock without cleavage, to which the 

 term slate is usually applied. ... It is not con- 

 venient or necessary to apply any other term than 

 slate to these rocks." A slate without cleavage! 

 Again, on p. 173: "the complete granulation of 

 constituents is sometimes expressed by the term 

 mylonite." The complete granulation of the con- 

 stituents of a rock gives rise to a granulite, not a 

 mylonite. Granulites and mylonites may be pro-, 

 duced from one and the same rock, but not under 

 the same conditions ; hence the necessity of keep- 

 ings the terms distinct. 



The third part of the work treats of such ques- 

 tions as the methods of distinguishing meta- 

 morphic rocks of igneous from those of sedi- 

 mentary origin, and the relation of the saline 

 constituents of ocean, lake, and river waters to 

 the metamorphic processes. The laboratory 

 methods described in the last part relate chiefly to 

 methods of computation and to the construction 

 of graphs, not to methods by which new chemical 

 or physical data are obtained. 



OUR BOOKSHELF. 



Exercises in Practical Physics. By Prof. A. Schuster 

 and Prof, C. H. Lees. Fourth Edition, revised. 

 Pp. X + 379. (Cambridge : At the University 

 Press, 1915.) Price 7^. net. 

 This well-known text-book, the first edition of 

 which was reviewed in Nature of February 20, 

 1902, now appears in a revised form. A com- 

 parison petween the present volume and an earlier 

 edition shows few changes of great importance. 

 Additional paragraphs have been supplied at the 

 ends of some of the sections, but only a small part 

 has been rewritten. A new section on the deter- 

 mination of dip by means of the dip circle is 

 given in an appendix. A more drastic revision 

 would have improved the book greatly, and 

 brought it more into touch with modern methods. 

 The increased use now made in physical labora- 

 tories of commercial ammeters and voltmeters 

 would not be realised by a teacher depending only 

 on this volume. We do not find a single exercise 

 in connection with electrostatic measurements. 

 In section Ixvi. the Weston cell is now described 

 as the standard cell, and all reference to the 

 Clark cell is omitted ; in the following sections, 

 however, the Clark cell is still mentioned as the 

 standard. In the measurement of wave-lengths, 

 Rowland's table is referred to, but no mention 

 is made of the new international scale of wave- 

 lengths. In spite of its somewhat old-fashioned 

 character, the book remains an excellent one both 

 for the teacher and the advanced student. 

 NO. 2417, VOL. 96] 



Bacon's Sixpenny Contour Atlas. Northern Wales 



Edition. Pp. 41. East Anglia Edition. Pp. 



41. South-west England Edition. Pp. 41. 



(London: G. W. Bacon and Co., Ltd., n/d.) 



Price 6d. net each. 

 Thirty-six pages of coloured maps and an index 

 to towns is certainly good value for sixpence. 

 Four of the maps — communications, geological, 

 relief, and vegetation — vary with the ditterent edi- 

 tions. Of the others, twenty-five are contoured 

 maps, on various scales, of different parts of the 

 world, and the remaining pages contain nine maps 

 of the world to show dirterent distributions. The 

 somewhat fantastic chart of geographical terms 

 on the last page might well be replaced by another 

 map. We feel also that the two-page introduction 

 to the special maps would scarcely be intelligible 

 to the children for whom this excellent little atlas 

 is designed. The maps are clearly printed, and 

 the colouring on the whole is good. It would be 

 an advantage if the British Isles could be shown 

 in relation to the Continen-tal border of the North 

 Sea, rather than as isolated islands, and if India 

 could be shown on a larger scale. Most of the 

 maps show no railways, but political frontiers 

 are marked by dotted lines. The projection used 

 is indicated on every map, and on a few England 

 is shown on the same scale for purposes of com- 

 parison. This should be done on all the extra- 

 European maps. The use of these atlases in 

 lower forms would certainly be of assistance in 

 the teaching of geography. R. N. R. B. 



Termodynamik. By P. B. Freuchen. Pp. 143. 



(Kobenhavn : Lehmann and Stages Forlag, 



1915.) No price. 

 The scope of this little book is best indicated by 

 the sub-title : " An outline of the history of thermo- 

 dynamics and the significance of the two chief 

 laws." In the preface the author declares his 

 intention of tracing the development of thermo- 

 dynamical ideas and their bearing on physics and 

 chemistry. It is not a text-book, but rather a 

 kind of thermodynamical "Who's Who"; suc- 

 cessive short chapters deal with Carnot, Clapey- 

 ron, William and James Thomson, Robert Mayer,, 

 etc. One of these begins: "To read Planck's 

 thermodynamical papers is to breathe pure, clear 

 air." 



The various parts of the subject are treated at 

 unequal length ; some, which are dealt with in the 

 larger text-books of physics, are entirely omitted. 

 Julius Thomsen's and Horstmann's work is 

 described more fully, but like many other his- 

 tories, this does not concern itself greatly with 

 the recent past, so that Nernst's theorem occupies 

 only half a page, and the quanta theory is referred 

 to in a single sentence. Although unsuitable for 

 beeinners, the book should appeal to physicists, 

 and particularly to chemists desirous of extending 

 their outlook. Its publication in Danish speaks 

 well for the scientific public of small countries, and 

 we hope that by means of a translation it may 

 become accessible to a larger number of readers. 



G. B. 



