KNOWLEDGE. 



September, 1912. 



an abode of life, and it is a mastfrly siiiiimarv of ttu- tlicories, 

 of the ani'iicics at work, of llu' bcjjinniuKs of life, of the varied 

 procession of the animal kingdom with its b;ickgronnd of 

 geographical scenery and veKet.ible life. 



Mr. (Irew h,as an interestinK chapter on age and climate, and 

 discusses the possible efTect of radio-.ictivity on this problem. 

 He says nothing of Croll's astronomic theory of "Climate 

 .and Time." Surely altered eccentricity to the extent of 

 thirteen millions of miles must aflfect cliinafe, and must .iffect 

 ocean levels. It may not have so stupendous an elfoct as its 

 originator suggests, but it must have an action that would have 

 been worth discussing in so full a treatment of the subject 

 as is given in ihis book. A long severe winter in one hemi- 

 sphere during which most of the polar water must fall as snow, 

 will assuredly be strikingly difTerent from the other polar 

 hemisphere, where during the short mild winter most of the 

 condensed water will fall as rain, and hence flow off, and 

 leave the earth surface ready to be warmed at once by the 

 sunniier sun : where;isthe summer sun in the other hemisphere 

 must obviously be largely engaged in melting the ice that has 

 accumulated in the long cold winter. There is but little doubt 

 that Croirs theory is deserving of more attention than it has 

 received of late years. This very able book, so largely devoted 

 to contrasting and estimating the value of rival theories, and 

 that so clearly shows the unsatisfactory nature of most of them, 

 will doubtless help to a revaluation of theories that have been 

 too hastily rejected, and help much towards a solution of many 

 problems. No impression of this book is more evident than 

 that the study of generalizations is the urgent need of the 

 moment. The book is heartily recommended to every one of 

 the readers of " Knowledge " ; it is as interesting as a novel, 

 and is especially characterized by the same aim as that of 

 " Knowledge," namely the subject is plainly worded ;ind 

 exactly described. 



A. \V. H. 



MINEK.^LOGY. 



Gcni-Stoncs. — By G. F. Herbert Smith. 312 pages. 



iZ plates. 7^-in.X5-in. 



(Methuen & Co. I^rice 6- net.) 



Besides forming an excellent work of reference and giving 

 details as to the articles and manufacture of stones and 

 methods of mining, Mr. Herbert Smith's book is of consider- 

 able interest to the general reader. A chapter is devoted to 

 " Historical Diamonds," for instance, and remarks are made 

 as to the powers of resistance which stones used in jewellery 

 should have against the mechanical and chemical actions of 

 everyday life. Gem-stones, we are told, should be at least as 

 hard as the minute grains of sand in ordinary dust. This is 

 a condition fulfilled by all the principal species with the excep- 

 tion of opal, turquoise, and one or two others. The beauty of 

 the first-named does not depend upon the brilliancy of its 

 polish, so that surface scratches are not of much importance. 

 If there is the slightest degree of porosity the stone is likely to 

 be affected chemically. It is risky to wet tuniuoises, even 

 with water, lest the bluish-green colour be oxidised to the 

 despised yellowish hue. There is some chance of opals, moon 

 stones and star stones being damaged by the penetration of 

 grease into their interior, and as the charm of pearls may 

 easily be destroyed in the same way or by contamination with 

 grease, ink, or similar matter, while they are also soft, their use 

 in rings is much to be deprecated. The book contains a 

 wealth of illustrations, and the plates in three colour give a 

 very good idea of the tints and appearance of the stones shown. 



NATURAL HISTORY. 



Tlic Arctic Prairies.— By Ernest Thompson Seton. 



415 pages. 54 illustrations. 9-in.X6-in. 



(Constable & Co. Price 12/6 net.) 



The many admirers of Mr. E. Thompson Seton's work will 



welcome this account of a canoe-journey of two thousand 



miles which he made at his own expense and for his own 



pleasure, in search of the Caribou in the far North-West. 



The book consists of a graphic account of travel, of natural 



history observations, illustrated with thumb-nail sketches, 



finished drawings of animals and with photographs. In fact. 



almost everything that was new or interesting to Mr. Seton 

 is represented, from the dry wallows in which the buffaloes 

 get relief from llies, to the lootprints of the black bear and 

 musk-ox, primitive windl.isses, birch bark pails, and the various 

 pl.ints that were noticed from time to time. Mr. Seton not 

 only saw many and great herds of the deer which he went so 

 far to find, but met with numerous things which he did not 

 e-pect and which in his own inimitable .style he brings 

 before his readers. 



Wimbledon Common. — By Walter Johnson. 304 pages. 

 4 maps. 25 illustrations. 8}-in.X5i-in. 

 (T. Fisher Unwin. Price 5;- net.) 

 In these days it is being abundantly recognised that the 

 study of history and geography should begin at home, and it is 

 <|uite obvious that those who are attracted by their natural 

 environment will turn first to what is nearest at hand. To 

 those who are not aware of the interest which can be found 

 even in a London suburb which is blessed by the possession 

 of open spaces, this account of Wimbledon Common will come 

 as a surprise ; and we may confidently say that everj- person 

 who claims to be intellectual, and who lives in the neighbour- 

 hood, should read the book, while it should serve as an example 

 and an encouragement to dwellers in other neighbourhoods to 

 collect material for similar and equally valuable compilations. 



ORNITHOLOGY. 



.4 Hand-List of British Birds vi'ith an account of the 

 Distribution of each species in the British Isles and 

 Abroad. — By Ernst Hartert, F. C. R. Jol'RDain, N. F. 

 TiCEHURST and H. F. Witherby. xii. and 237 pages. 

 8'-in. X 5i-in. 

 (Witherby & Co. Price 7 6 net.) 

 This work is c tain to prove most useful to ornitholo- 

 gists, supplying, as it does, in one volume of moderate size 

 and in concise terms, a mass of detailed information only 

 available hitherto in various separate "Publications. It may 

 well rank as the British ornithologist's vade-mecum ; for our- 

 selves we have found that, in the short time it has been in our 

 hands, it has already secured a place of preference as a source 

 of reliable information, and that we are continually referring 

 to it. The title indicates the ground covered, and in addition 

 notes are given on the migration of some species. .\s regards 

 distribution, this is given with considerable detail for each of 

 the three countries of the United Kingdom separately, and 

 frequently for smaller geographical divisions, and this arduous 

 and laborious task has been accomplished with completeness 

 and success. The distribution abroad is also brieliy given. 

 It is rather to be regretted, however, that, in aiming at 

 conciseness of language, telegraphese EngUsh is used, some- 

 times to the extent of obscuring the meaning of the sentence. 

 .\n admirable brevity would still have been preserved had 

 the authors allowed themselves the conventional use of 

 conjunctions and prepositions. The number of species 

 on the British list steadily increases and the present work 

 •admits four hundred and sixty-nine, as compared with Howard 

 Saunders' " List " (1907) which has four hundred and fifteen, 

 excluding doubtful records. We think that a brief analysis 

 and summary into groups, such as resident birds, summer 

 visitants and otherwise would have been instructive as 

 bringing out one of the striking characteristics of our 

 avifauna. 



The distributional portion of the book is, we are sure, what 

 the working ornithologist will most value, but it should be said 

 that the authors seem to consider nomenclature to be of equal, 

 if not greater, importance. They have certainly had the 

 courage to place a heavy handicap on the acceptability of their 

 work, by the sweeping and radical character of the changes 

 made in the scientific names. Many of the bibliographical 

 and critical notes elucidating this part of the work are of great 

 interest, but the system which imposes such names as 

 Troiilodytcs troglodytes troiilodytes (L.) on the Wren (and 

 there are many other similar names), has taken upon its 

 shoulders a \ery heavy burden indeed, — even although it is 

 based upon pure reason. Appearances are against it. 



H. B. W. 



