548 



NATURE 



[October 26, 191 1 



theory and laboratory work suitable for various ex- 

 aminations of the standard of London matriculation. 

 The general arrangement of the work is very neat 

 and methodical, descriptions of the experiments in 

 connection with the theory being appended to each 

 chapter. There are also numerous examples collected, 

 principally from papers set in the London matricula- 

 tion. The author has adopted the "ray" method, 

 since he regards it as easier to understand than the 

 " wave " method; but he is careful to proceed in such 

 a manner as to admit of the development of the wave 

 theory at a later stage without apparent contradiction, 

 and, in the final chapter, introduces the student to the 

 elements of this theory. To those who need the 

 information it supplies this book may be in all respects 

 thoroughly recommended. 



(5) This consists of a series of simple experiments 

 in heat, light, electricity, and sound. The procedure 

 is to give the boy exact instructions of what to do, and 

 to tell him to observe and record his results. Occa- 

 sional questions bearing on the experiments are also 

 asked. This method is certainly preferable to that 

 which is sometimes adopted, viz. to allow the student 

 to invent his own experiments. As the author points 

 out, the ordinary schoolboy is usually incapable of 

 originality in a subject which is new to him, and 

 should at first, at any rate, follow instructions im- 

 plicitly. In schools this collection .of experiments 

 should be found useful. 



(6) The leading feature of this text-book is the ex- 

 traordinary amount of ground covered in relation to 

 the size of the volume. Attention is devoted to all the 

 usual branches of physics, and many details are found 

 which seldom occur in elementary treatises ; indeed, 

 from a purely descriptive point of view the work 

 should suffice, not merely for preparation for inter- 

 mediate, but also for final examinations. This con- 

 densation of material has been made possible, how- 

 ever, only at the expense of that mathematical 

 treatment which is essential for both examinations. 

 That this is no oversight is clearly indicated by the 

 author's preface, in which it is asserted that mathe- 

 matical reasoning, even of a simple sort, is found a 

 stumbling-block by many students. This may be true, 

 but we cannot agree that it forms a justification for 

 overlooking the fact that an exact knowledge of 

 physics is impossible without frequent recourse to 

 mathematical processes. From the author's point of 

 view, however, consistency demands that no unproved 

 formulae should be quoted, but this is by no means 

 the case. The result of this avoidance of exact treat- 

 ment has been to render the book very unequal, the 

 descriptive portions being distinctly adequate and 

 good, but (he equally essential mathematics is looked 

 for in vain. In fact, the contents may be described 

 as insufficient for the serious student, and at the same 

 time much too detailed to be useful as a popular treat- 

 ment of the subject. The type and diagrams are good, 

 and the more important statements are either in heavy 

 type or in italics. 



17) Their is no subject in which there is a greater 

 nd for books on popular lines than electricity. 

 This pamphlet forms the first part of such a book, and 

 is devoted to electrostatic? and magnetism. 

 NO. 2191, VOL. X- ! 



OUR BOOK SHELF. 

 Geologisclicr Ftihrer dutch das Mainzet Tertiarbecken. 



By Dr. C. Mordziol. I. Teil, Allgemeine t bersicht 

 und Exkursionsfiihrer in die Umgebung von Mainz 

 und Wiesbaden. Pp. xii + [68, with 39 figures in the 

 text. (Berlin: Gebriider Borntraeger, 1911.) Price 

 5.60 marks. 

 I n view of the increasing interest taken in Germany 

 in field geology, it is to be regretted that this small 

 guide to a very accessible district should be issued 

 at so high a price. Schubert's Dalmatia in the same 

 series is, in fact, slightly cheaper, and students at 

 Bonn, Giessen, and Heidelberg may feel that they have 

 a right to more liberal treatment. Dr. Mordziol, of 

 Aachen, indicates at the outset the limits of the basin 

 of Mainz, a region of subsidence, in which the youngest 

 deposits lie in the centre, while the older Cainozoic 

 strata appear upon the margins. The gravels laid 

 down by the Rhine in glacial times actually lie below 

 the present level of the sea .(p. 2). On the south, the 

 basin merges into the sunken valley-floor of the upper 

 Rhine, as is apparent on any orographic map of 

 southern Germany. 



The hilly ground bordering on the basin includes 

 a great variety of rocks, and the problem of the 

 gneisses on the south side of the Taunus, which may 

 be of Devonian age, is regarded as still undecided. 

 The true interest of the basin itself lies in its Cainozoic 

 stiata. The author (p. 15) supports Sandberger's divi- 

 sion of Oligocene from Miocene at the base of the 

 Cerithium limestones, in opposition to Dollfus and 

 Steuer, who include this limestone and the whole 

 brackish water series above it as Miocene. These 

 strata are clearly described and illustrated, and the 

 terrestrial sands and gravels (p. 65), derived from the 

 decay of earlier Cainozoic and still older rocks, are 

 held to be of Lower Pliocene age. We may remember 

 that the Deinotherium beds of Eppelsheim, north-west 

 of Worms, containing Mastodon, Machairodus, and 

 Hipparion, are included in this interesting ana. 



The author, in tracing characteristic siliceous 

 pebbles onward from the Hipparion-sands into Hol- 

 land, makes out a case for the existence of a pre- 

 glacial northward-flowing Rhine (p. 68). He then 

 proceeds to illustrate the basin by a series of excur- 

 sions, in which the underlying Permian strata are not 

 overlooked. An index of places is much needed, 

 but will probably accompanv the second part. 



G. A. J. C. 



Evolution. By Prof. Patrick Geddes and Prof. J. 

 Arthur Thomson. Pp. 248. (Home University 

 Library of Modern Knowledge.) (London : Williams 

 and Norgate, n.d.) Price is. net. 

 Profs. Geddes and J. Arthur Thomson have added 

 vet another to the large number of books already 

 existing which are designed to deal with evolution in a 

 manner suited to the needs both of the beginner in 

 serious study and of the general reader. The reputa- 

 tion of the authors will have led us to expect at least 

 accuracy in the statement of facts, and this anticipa- 

 tion is certainly fulfilled in the little volume before us. 

 Apart from the region of fact, we seem to discern a 

 twofold influence at work, leading, on one hand, to 

 a caution in interpretation so extreme as sometimes, 

 we fear, to confuse the inquirer; and admitting, on 

 the other, a boldness of speculation which is some- 

 what likely to disconcert him. 



\*. in example of the former tendency may be 

 mentioned the authors' manner of dealing with the 

 crucial question of the inheritance of somatic modifica- 

 tions. No uncertain sound should be given an a point 

 like this, but it is doubtful whether die student with 

 onlv the present book before him would be as much 



