124 



DISCOVERY 



ones, is insisted on, as indispensable for the accurate 

 delimitation of species in systcmaty ; maxima and 

 minima for the primordia being regarded as " specific 

 constants." There is no objection whatever to this being 

 done ; the fact that it has not been generally done in the 

 past is merely a question of labour and the immense amount 

 of available material in even a small flora. The field is 

 quite open to anyone who cares to spend his life in the 

 acquisition of such laborious data. Wliat one wants to 

 know, of course, is what good will come of it. Extended 

 examples are given of the possibilities of variation curves, 

 variation "steps," and " gradation curves " ; the com- 

 bination of such data, constituting a quantitative diagnosis 

 of a species, is defined as " BertiUonage " ; but the 

 application of the method for the determination of accepted 

 species is not particularly convincing ; it being sufficiently 

 obvious that what are termed species by a systematist are 

 still empiricisms wholly lacking any precise standard of 

 reference. It is in thus drawing attention to the general 

 rottenness of the foundation of systematy, as also to the 

 fact that the ordinarj* collector has but the vaguest notion 

 of the range of type in the forms he deals with over only a 

 small area, that the work attains, perhaps, its greatest 

 value. The text is plentifully decorated with italics and 

 headings in large capitals, and under other conditions, 

 possibly, might have been published in German. 



Economics for To-day. By Alfred Milnes, M.A. 

 (J. M. Dent & Sons, 3s. dd. net.) 



With certain reservations we can recommend this book 

 cordially to readers who wish to make a first acquaintance 

 with economics. It is clearly written, and is furnished in 

 many places with good illustrations. It should thus 

 enable a young student or a beginner to obtain a grasp of 

 the outlines of the subject without having a teacher at his 

 side to explain the difficulties of the subject to him. But 

 reservations must be made with regard to the chapter on 

 the Inland Market, in which the author is not so happy 

 in his exposition. Thus there is a point on p. 113 about 

 the demand for money ; whether this refers to the quantity 

 theory of money in its crudest form, or to something else, it 

 is difficult to say, and no explanation is offered. Again, 

 about the same place, use is made of three expressions, 

 " demand-price curves," " demand-value curves," and 

 " quantity-value curves," without any indication of the 

 differences between them, if any ; which is somewhat 

 confusing, especially as none of these expressions are at 

 all commonly used by economists, let alone general readers. 

 The reference (p. 122) to " various prices " at which 

 demand and supply can balance is also not very clear. 



Apart from the ambiguities of this particular chapter, 

 there are one or two slips which should be corrected in a 

 subsequent edition. At present, thanks to the recent 

 epidemic of amalga^nations, there are eleven and not 

 eighteen clearing banks (p. 217). Also, it is hardly correct 

 to say that the Bank Charter Act has been suspended four 

 times (p. 220) — it was only in 1857 and in 1914 that notes 

 were issued in excess of the statutory limit. The price of 

 the four-pound loaf in England before the war was nearly 

 si.xpence, so that the statement (p. 225) that it sold "for 



little more than threepence " hardly conveys the correct 

 impression. 



In spite of these small defects, Mr. Milnes's book is a 

 welcome addition to the literature of elementary economics, 

 and is adapted to the needs of the general reader as well as 

 those of young students. The publishers are to be con- 

 gratulated on producing the book in a presentable style at 

 the — to-day — very moderate price of 3s. bd. net. 



D. K. 



Evening Play-Centres for Children. Bj- Janet Penrose 

 Trevelyan. (Methuen, 5s. net.) 



This is a very well written book on a subject that is of 

 great interest to everyone who has the welfare of the 

 poorer children of our towns at heart. It should interest 

 particularly social and settlement workers. 



It is now twenty- two years since the first play-centre 

 for children was opened at the Passmore Edwards Settle- 

 ment in Bloomsbury. Mrs. Humphry Ward was the 

 pioneer of the movement, and to her courage and energy 

 and that of her helpers is due its remarkable progress. 

 In this book Mrs. Trevelyan gives a history of the 

 movement, and an account of its principles, objects, and 

 results. From the small beginning, the movement has 

 grown till it now embraces 300 centres in the provinces, 

 and over 30 in London. 



These centres, needless to say, have had good influences, 

 not only on the children attending them, but also on their 

 parents. 



Vacation schools and organised playgrounds are also 

 described with inside knowledge ; and, in appendices, 

 details dealing with the formation of play-centres, and 

 descriptions of nearly a hundred suitable games, are given. 



Mrs. Humphrv Ward contributes a preface. 



P. K. F. 



Meteorology for All. By D. W. Horner. (Witherby, 

 6s. net.) 



The Prifwiples of Aerography. By Prof. A. McAdie. 

 (Harrap, 21s. net.) 



Both these books are good ones, for by reading either of 

 them through one gets a verj' good idea of the subject. 

 Both are informative. By means of facts, tables, diagrams, 

 and photographs, a fund of information is conveyed to the 

 reader. Both are written in an interesting manner, so that 

 the general reader can read right through without being 

 bored. 



Mr. Horner's book is written for a wider audience than 

 Prof. McAdie's. It is meant, as the title implies, for every- 

 body. Not for everybody, of course, but for all those who 

 wish to have acquaintance with the methods of forecasting 

 the weather, and who are interested in clouds, snow, light- 

 ning, and wind, and the why and wherefore of the pheno- 

 mena connected with them : who, instead of cursing the 

 " Clerk of the Weather " as a fool, and believing that the 

 prediction of weather is impossible, want to know how 

 far one can predict the vagaries of the weather, and 

 along what lines tlie solution of the outstanding problems 

 of the science is to be sought. Mr. Horner gives a good 



