DISCOVERY 



189 



about it. Substitutes for rubber have been exemplified 

 for years in the case of the composition used for printers' 

 rollers ; this used to be a mixture of glue and treacle 

 which sets into an elastic, rubber-like substance ; to-day 

 the treacle has been replaced by glj'cerine, but the 

 properties of the composition are much the same. 

 Rubber, one way or another, accompanies man through- 

 out his earthly pilgrimage. As an infant his soother 

 is composed of it ; later on, if successful, the tyres 

 of his motor are shod with it ; and by means of 

 a vulcanite pen he signs his cheques and other papers 

 with it ; while after nature has failed him, the founda- 

 tion of his latest teeth is ubiquitous rubber. 



Reviews of Books 



Aviation. By B. M. Carmina. (The Macmillan 

 Company, iis. net.) 

 The author, who is Assistant Chief Instructor at the 

 Y.II.C.A. Airplane Mechanics School, discusses the subject 

 both from a theoretical and a practical point of view, and 

 his book should prove of special interest to those engaged 

 in the construction, maintenance, or designing of aero- 

 planes. The book, which is copiously illustrated, deals 

 very fully with the practical side of the question ; and 

 the index will make it valuable as a work of reference. 

 Mr. Carmina writes best when he is giving information 

 which has been obtained as the result of experience, 

 such as the reasons for the choice of the various materials 

 used, the advantages of the tractor t>-pe over the pusher, 

 the value of giving curved surfaces to the wings, etc. 

 His use of phrases like " horizontal and vertical stabilisers 

 for tail and fin," although somewhat cumbrous, tends to 

 make his work clearer ; the study of aviation has been 

 made in the past needlesslj' confusing by using 

 misleading terms, e.g. planes for wings. The author is 

 less happy when dealing with the theoretical side of the 

 subject, partly perhaps because he has attempted the 

 impossible task of giving explanations of a scientific 

 nature suitable to non-scientific readers. This perhaps 

 accounts for loose statements like (p. 12) " what we 

 would gain Ln Uft we would lose in weight " ; and for 

 the error in his definition of centre of pressure (p. 10), 

 though this, in viev.' of the fact that it is correctly defined 

 on p. 152, may be due to carelessness. 



The book is excellently printed, and the only misprint, 

 which might give rise to confusion, is on p. 157, where 

 the metre is stated to be 3037 inches, nine inches too 

 short. T. B. M. S. 



rite Geography of Plants. By M. E. Hardy, D.Sc. 

 (Clarendon Press, 7s. 6d. net.) 

 Seven years ago Dr. Hardy's Introduction to Plant 

 eography was published. This new book of his is a 



nore ambitious £ind a more advanced work on the same 



IContinutd on p. 190 



Mr. Murray's New Books 



A DESCRIPTIVE LIST OF NEW BOOKS 

 WILL BE POSTED FREE ON REQUEST 



THE LIFE OF 



BENJAMIN DISRAELI 



EARL OF BEACONSFIELD. By G. E. BUCKLE 

 in succession to \V. F. MOXVPENNY. One result 

 of the war h.is been the interiuption of the progress of 

 the famous Life of Benjamin Disraeli, but the del.iy in 

 publication has had one unexjieclcd and most fortunate 

 result, as it has enabled .Mr. Buckle to get access to a 

 large and singularly interesting budget ol private corre- 

 spondence of the highest value in respect of Lord Beacons- 

 field's later years. Volumes V and VL completing the 

 work, will be published in June. 1 8s. net each. 

 Previously published, Volumes I — IV. 15s. net each. 



THE GREAT WAR, 1914—1918 



Ily C. R. L. KLETCIIEK, M.A., formerly Fellow of All 

 Souls and Magdalen Colleges, Oxford. A living story of 

 the principal events on all fronts told in a vivid, picturesque 

 style. With Maps. 6s. net. 



THE SECRET CORPS 



By Captain FERDINAND TUOIIY. For the first 

 time the authentic and detailed story of "intelligence" on 

 all fronts is told. Not only is Captain Tuohy's book of 

 great value as a record of the unknown side of the late 

 war, but it is full of human Inecdotes and incidents pre- 

 sented in picturesque language. 75. 6d. net. 



MICROSCOPY 



THE THEORY, CONSTRUCTION, AND USE 

 OF THE MICROSCOPE. By EDMUNDJ. Sl'ITTA, 

 F.R.A.S., F.R.M.S., past President of the Ouekeit 

 Microscopical Club. New and Enlarged (3rd) Edition, 

 conlaining 83 half-tone reproductions and 255 text illus- 

 trations. 25s. net. 



DIPLOMATIC 

 REMINISCENCES, 1911—1917 



By .\. NEKLUDOFF. During the period of which he 

 wiius, M. NekludofTwas Russia's representative at Sofia, 

 Stockholm, and Madrid. In the course of his service he 

 had interviews with many leading personages, and his 

 records are of profound interest and importance. 2 IS. net. 



CONIFERS and their Characteristics 



By C. COLT.MAN-ROGERS. This book is an invaluable 

 aid in identifying the many different species of trees in- 

 cluded in the category of the Natural Order of the 

 Conifer* ; it also gives much reliable and interesting infor- 

 mation concerning their life-history. Illustrated. 2is.net. 



THE 



HERON OF CASTLE CREEK 



AND OTHER SKETCHES OF BIRD LIFE. By 



A. \V. REtS, Author of " lanio the Fisherman," etc. 

 With a Memoir of the Author by J. K. HUDSON. 

 " A book not to be forgotten ; it will be treasured by 

 many a Nature-lover, and its usefulness will not end with 

 one generation. ■' — Liverpool Daily Courier. 7s. 6d. net. 



LONDON: JOHN MURRAY 

 ALBEMARLE STREET, W. 



