Febri-arv. 1915. 



KNOWLEDGE. 



63 



inorpMsm of rocks, and with rock weathering and soils. 

 Chapters V to X deal more directly with the practical 

 aspects of geology in relation to surface and underground 

 waters, land sUdes, waves and shore currents, lakes and 

 glacial deposits. The remaining chapters demonstrate the 

 importance of geological principles in the winning and 

 selection of building stones, hmes, cements, plasters, clays, 

 coals, petroleum, road metals, and ore deposits. 



The book is illustrated with one hundred and four excel- 

 lently selected and well-executed plates and tvvo hundred 

 and twenty-five figures, some of which are open to criticism. 

 Thus Figure 73, which, according to the designation, is 

 intended to show monoclinal attitude of strata, shows simple 

 dip, and is, moreover, not referred to in the text. In 

 Figure 74 the shading does not correspond in the t^vo 

 drawngs. The plan and section do not correspond in 

 Figure 116, whilst in Figure 64 there is an extraordinary 

 lack of deformation in the strata adjacent to a broad 

 fault-breccia zone. 



Since the book has been written for the .\merican student, 

 we can hardly be surprised that American examples abound 

 in the text, and that Anierican literature is mainly cited in the 

 concise lists of literature at the end of each chapter. Never- 

 theless, the plan of the book is so good that European 

 engineers will find its methods and principles adapted to 

 all their problems, although it is to be hoped that this book 

 will stimulate some worker wdth the necessary quaUfications 

 of engineer and geologist to summarise the extensive but 

 scattered British Uterature on the same subjects. 



G. W. T. 

 MATHEMATICS. 



A First Course in Mathematics for Technical Students. — 



By P. J. Hales and A. H. Stuart. 125 pages. 



7|-in.x5-in. 



(University Tutorial Press. Price 1 /6.) 



The material in this little book is practical and much 

 condensed. It will probably be found useful to the type 

 of student for which it is intended. The explanations 

 seem to be full in some cases and meagre in others ; but 

 those who have had experience in practical work with 

 artisan students must know that their difficulties are not 

 the same as those of the ordinary schoolbov. 



W. D. E. 



Elementary Mathematical Analysis. — B}' C. S. Slighter. 

 490 pages. 7i-in. x 5 J-in. 



(Hill Publishing Company. Price 10/6 net.) 



A textbook in which efficiency (in Lord Rosebery's sense) 

 appears to be the watchword. Everj'thing is standardised, 

 even to the size of the paper on which the student works in 

 pen and ink It almost comes as a surprise that a type- 

 writer is not insisted on, and that no American standard of 

 pronunciation of the letters of the Greek alphabet is set up. 

 The author lays stress on the possibilities and responsibilities 

 of character-building in a mathematical course, and we find 

 occasional hints, amounting to commands, intended for the 

 instructor. Although the inspiration of Professor Klein of 

 Gottingen is freely acknowledged, the book should prove 

 innocuous, and even beneficial, to English-speaking teachers 

 of mathematics dispersed throughout the world. 



W. D E. 



Plane Trigonometry. — Bj' C. I. P.\lmer and C. W. Leigh. 

 288 pages. 9J-in. x 6J-in. 



(Hill PubUshing Company. Price 6 /3 net.) 



The treatment of the subject in this book is not at all 

 that which has been adopted in many recent textbooks. 

 The authors begin with the measurement of angles, positive 

 and negative, and make use at once of Cartesian coordinates . 

 There is something to be said for this method of procedure ; 

 for most boys are made famUiar with graphs nowadays 

 before beginning trigonometry, and it is just as well to 

 make use of this famiharity. The trigonometrical ratios 



are defined at the outset for the general angle, and then 

 specialised for the acute angle. Many teachers have done 

 this in times past, and with success in the case of intelligent 

 boys. The clear diagrams in this book seem to indicate 

 that the authors have themselves found this plan successful. 

 The second part of the book consists of a xery good set of 

 tables, with full explanations, the angles from 0° to 360° 

 being all included. Altogether the book merits the attention 

 of teachers, and can be recommended without hesitation 

 for intelligent students who wish to obtain quickly a 

 practical knowledge of the subject. By way of criticism, 

 it may' be said that the saving of time involved in writing 

 esc e for cosec e must in practice be very small, and may 

 cause confusion. 



\V. D. E. 



NATURAL HISTORY. 



Ktld Life : An Illustrated Monthly, Vol. VI, No. 1. — 



Edited by Douglas English. 32 pages. Numerous 



illustrations. 12-in. x 10-in. 



(The Wild Life Publishing Co. Price 2 /6 net.) 



An editorial in Wild Life for January frankly states that 

 its issue was delayed until it had been ascertained 

 to what degree the war had affected its subscription hst. 

 The fact that once more the magazine has made its appear- 

 ance shows that the thanks offered to the readers is not 

 an empty compliment. The number contains, as usual, some 

 excellent photographs, of which we may mention Mr. 

 Oswald Wilkinson's picture of the male willow warbler 

 cleaning its nest. Mr. Alfred E. Tonge concludes his 

 illustrated account of " British Clearwing Moths." The 

 first part of this appeared in the December number, and 

 from it we are here permitted to reproduce Figure 59, 

 which is an exceedingly good representation of the six- 

 belted clearwing [Sesia ichneutnoniformis). Another picture 

 in the current issue, which is very striking, is INIr. D. Seth 

 Smith's photograph of a Guinea baboon, used to illustrate 

 Mr. E. G. Boulenger's monthly " Notes from the Zoological 

 Gardens." 



W^ M. W. 



PETROLOGY. 



Textbook of Petrology : The Igneous Rocks. — By F. H. 

 Hatch. 429 pages. 164 illustrations. 7i-in. x5-in. 



(George AUen & Co. Price 7/6.) 



According to the preface, the seventh edition of this well- 

 known textbook on Igneous Rocks has been prepared in 

 order that it may constitute the first volume of a general 

 work on petrology, the second volume being the recently 

 issued " Petrology of the Sedimentary Rocks," by Hatch 

 and Rastall. ^^'hile the general arrangement is the same as 

 in the fifth edition, much of the text has been revised, and 

 new chapters on the pyroclastic and the metamorphosed 

 igneous rocks have been added. The book is divided into 

 four parts, the first being concerned with the physical 

 characters of rocks, the second with the rock-forming 

 minerals, the third with the classification and description 

 of the various rock-types, while in the fourth an account of 

 the distribution of these types in the British Isles is given. 

 The first two parts are eminently satisfactory, and the 

 facts are presented in a most lucid and readable form. 

 The intioductory chapters in the third part are not so 

 satisfactorj', chiefly owing to the fact that the classification 

 adopted is that of siUca-percentages, and that the graphical 

 methods of indicating the relation of rock-groups, which 

 are described, are the " oxide " methods of Iddings and 

 Broggcr. No mention is made of quantitative classification, 

 either on the basis of norm or mode, nor of the exceedingly 

 useful graphical methods based on these factors. 



It is somewhat strange to find that most of the ultra-basic 

 rocks are relegated to the hypabyssal division, as many of 

 these are commonly plutonic. This also tends to obscure 

 the close relationship which sometimes exists between 

 diorites and hornblendites. The fourth part should prove 

 of great use, as it is very complete, though in places it appears 



