March, 1915. 



KNOWLEDGE. 



95 



lished. The literature of the subject is voluminous and 

 widely scattered ; much of it is purely descriptive, and 

 written from an empirical standpoint. The authors of 

 this volume have not only " digested " the literature, but 

 have endeavoured to give an account of the general principles 

 underlying the genesis and occurrence of ore deposits. 

 Witli tliis end in view, the description of separate occur- 

 rences has been inserted only as illustrative of these 

 principles. Therein the book differs from most previous 

 ones on the same subject, which have been more in the nature 

 of descriptive handbooks. 



The introductory part is concerned mainly with the 

 morphology and mineral content of the various types, 

 and includes an abundance of interesting and useful data 

 regarding the association and relative amounts of the 

 various elements in different ore fields. It is perhaps a 

 little unfortunate that Clarke's " Data of Geochemistry " 

 appeared too late for the wealth of information contained 

 therein to be utilised. The second part of the volume 

 deals with the difficult subject of classification, and the 

 evolution of this from the :norphological systems of von 

 Cotta and other early writers to the present-day genetic 

 ones, is traced. The one finally adopted by the authors, 

 while it does not differ radically from that of Beck, is in 

 advance of the latter in the subdivisions of the main groups. 



There are four main divisions : magmatic segregations, 

 contact-deposits, cavity-fillings and metasomatic deposits, 

 and ore-beds. These are subdivided on the basis of the 

 mineral content. It is only natural that the last of these 

 groups should be the least satisfactory', as it includes many 

 deposits the genesis of wliich is still very doubtful. The 

 remainder of the book is occupied by a systematic examin- 

 ation of the first two groups, and of the tin, apatite, and 

 mercury lodes in the third. 



It can unhesitatingly be said that the authors have 

 succeeded in their difficult task, and it is impossible to 

 praise too highly the skill with which they have correlated 

 the great accumulation of evidence. Furthermore, they 

 have been eminently successful in their presentation of the 

 genetic principles, and have shown that this branch of 

 geology has a considerable claim to rank as a rational science. 



On the whole, the translator has done his part well, 

 particularly in the rendering of the numerous technical 

 terms into English. In places, however, the diction is 

 unduly obscure, owing to a great deficiency in punctuation 

 marks. Some terms, such as " eutecticum " and " sodium- 

 granite," scarcely conform to English usage, while the use 

 of the name " labradorite " to designate a rock and a 

 mineral indiscriminately is somewhat confusing. The value 

 of the book is enhanced by a large number of excellent 

 illustrations indicative of the geological structure of the 

 various deposits; but the general "get-up," though 

 otherwise good, is marred by a number of misprints. Thus, 

 there is one in the table on page 149, another in the formula 

 of durdenite on page 219, while both " aragonitc " and 

 " arragonite " appear in the one paragraph. It is some- 

 what strange to see " aluminium " characterised as a mineral, 

 while on page 83 " atomic weight " is used instead of 

 " specific gravity." These, however, are only minor defects 

 in a most useful and readable book, which can be thoroughly 

 recommended to all interested in the subject. 



A. S. 



NATURAL HISTORY. 



Reptiles and Batrachians. — By E. G. Boulenger, F.Z.S. 

 278 pages. 202 illustrations. 9 J-in. x 6 J-in. 



(J. M. Dent & Sons. Price 16/- net.) 



Mr. Boulenger has produced a very attractive and at the 

 same time useful book : attractive because it is simply 

 written and has a wealth of really beautiful illustrations, and 

 useful because many of the reptiles and amphibians described 

 are commonly kept in captivity, or could easily be so with 

 little, if any, discomfort to themselves. Moreover, Mr. 

 Boulenger has introduced a classification which shows the 



systematic position of the animals without encroaching 

 unduly upon the space available for the consideration of 

 life-histories and habits. 



Any lover of nature will enjoy reading the book, even 

 if " cold-blooded " creatures do not specially appeal to him. 

 In dealing with the Tudtara of New Zealand, which has be- 

 come almost extinct on the larger islands, though it is 

 protected on the smaller ones in the Bay of Plenty, Mr. 

 Boulenger shows how rapid its extermination has been 

 by pointing out that while twenty-five years ago a specimen 

 could be purchased from almost any dealer for from twenty 

 to thirty shillings, the price is now about fifteen pounds. 

 The book contains some interesting notes on the Giant 

 Tortoises ; the South Albemarle Tortoise, attains the 

 length of five and a half feet and weighs nearly five 

 hundredweight. The eggs are about the size of a tennis 

 ball, and the young grow rapidly — in fact, when four years 

 old they are nearly two feet in length. .\n adult tortoise 

 may not increase in size for a hundred years or more, and 

 its length of life may be judged from the fact that specimens 

 have been kept in captivity for more than two hundred 

 years. These notes will give some idea of how the animals 

 are treated, and the book deals also with Crocodiles, Lizards, 

 and Snakes, besides the Batrachians : tailless, like the frogs 

 and toads ; tailed, like the salamanders ; and limbless, like 

 Ichthyophis and Typhlouectes. 



By the courtesy of the pubUsher, we are enabled to repro- 

 duce two of the illustrations, namely, that of the Chamaeleon 

 and that of the Cat Snake (see Figures 76 to 77). 



W. M. W. 



PHYSICS. 



The Dynamics of Surfaces. — by Professor Dr. "Med. 



Leonor Michaelis. Translated by W. H. Perkins, M.Sc. 



118 pages. 8 illustrations. 8|-in. x 5i-in. 



(E. & F. N. Spon. Price 4/- net.) 

 This book is intended as an introduction to the study of 

 biological surface phenomena, and is primarily written to 

 enable biologists to deal with the problems of surface 

 reactions more fundamentally than they have done hitherto. 

 We think that it will form an excellent guide to any serious 

 student of adsorption and allied surface effects. The 

 references to the literature of the subject are numerous, and 

 will greatly smooth the path of any explorer into this 

 important region of chemical physics. Such readers will 

 be found among biologists, but also among those who 

 approach the subject as chemists and physicists ; while the 

 scientific dyer will here find much that is of interest. We 

 find the book very free from misprints ; a curious one, 

 however, occurs on page 104, where, in a reference to a 

 paper by Rcinold and Rucker, the first-named author is 

 called " Reynolds." 



J. H. V. 



Smithsonian Physical Tables.— By Frederick E. Fowle. 

 Sixth Revised Edition. 355 pages. 9-in. x6-m. 

 (Wesley & Son. Price 8/6.) 

 These tables form one of a series of four volumes of tables 

 issued by the Smithsonian Institution, the others being 

 the Meteorological, Geographical, and Mathematical Tables. 

 In magnitude the Physical Tables are intermediate between 

 Kaye and Laby's Physical and Chemical Constants and 

 Landolt - Bornstein - Meyerhoffer's Physikalisch-chemische 

 Tabellen. An introduction of thirty-five pages deals with 

 units of measurement and conversion formulae : this is 

 followed by tables of formulae for conversion factors and 

 of numerical conversion factors. Tables of mathematical 

 functions now follow, including useful lists of differentials, 

 integrals, and series. The body of the book of Physical 

 Tables begins at page 68 with Strength of Materials, and 

 consists of accurate data on many subjects of importance 

 and interest to physicists, all well arranged and clearly 

 printed. The volume adds another debt which science 

 owes to the Smithsonian Institution. 



J. H. V. 



