January 26, 1922J 



NATURE 



103 



I 



citizens of the United States, nearly all its illus- 

 trations, verbal and pictorial, are taken from North 

 America and the possessions of the United States, 

 and all the references, with few exceptions, are to 

 American writers. In view of the fact, admitted 

 by the author, that " the future history of America 

 is to be inseparably connected with that of the rest 

 of the world." more attention might have been 

 directed to other countries; for instance, some of 

 the street-scenes in American cities might have 

 yielded to views in European or Asiatic capitals. 

 it is, however, right that geographical study should 

 begin with .the home region, and this idea fre- 

 quently finds express'ron in the inquiries suggested 

 at the end of each chapter — e.g. " Make a careful 

 study of the influence of geoeraphic environment 

 in your own State or locality. What factors are the 

 most important? Are there any national forests 

 in your State? Locate them. ' Is the Federal 

 Government aiding in road construction in vour 

 vicinity?" But other suggestions will broaden 

 the reader's outlook — e.g. " How will the economic 

 geography of France be changed by the restoration 

 of Alsace-Lorraine? What made possible the ship- 

 ping of meat and dairy products from Australia 

 and New Zealand to the British Isles?" These 

 ouestions cannot be answered from the book itself. 

 He Avho succeeds in answering them all will have 

 had to read and think much, and will have become 

 a more valuable citizen. 



Modern Hipt-siteed Influence Machines. By V. E. 

 Johnson. Pp. viii-f278. (London: E. and 

 F. N. Spon, Ltd., 1921.) 14^. net. 

 The author points out that electrostatic machines 

 are used much more on the Continent and in America 

 than in this country, where they do not appear to 

 be held in good esteem. He proceeds to argue that 

 this bad repute is undeserved, and proceeds to in- 

 vestigate the capabilities of this class of machine 

 and the conditions upon which its efficiency and 

 trustworthiness depend. Practically all the types 

 which have been proposed from time to time are 

 described and analysed, and accounts are given 

 of the author's own experiments, resulting 

 in a type considerably more efficient than 

 the well-known Wimshurst machine. He claims 

 that, as a source of high potential supply, 

 a high-speed influence machine designed on 

 the right lines should be as efficient as an 

 induction coil with all its accessories, and that, 

 principally on account of the continuity of its supply 

 and the higher voltage available, it should give 

 better results for Rontgen-ray work, particularly 

 with tubes for high penetration. Other fields in 

 which he suggests that such machines may prove 

 useful include applications to wireless telegraphy, 

 electro-culture, electro-therapeutics, ignition, and 

 the testing of materials. 



Although we find here and there a little looseness 

 of expression and vagueness in quantitative state- 

 ment, there is evidence of clear thinking in the con- 

 struction of a consistent theory of the action of these 

 machines from the mass of incomplete explanation 

 NO. 2726, VOL. 109] 



which is diffused among the existing literature on 

 the subject. There is also some thoroughly prac- 

 tical information as to the construction of these 

 machines. 



The Transition Spiral and its Introduction to Rail- 

 way Curves. By A. L. Higgins. Pp. viii-t-iii. 

 (London: Constable and Co., Ltd., 1921.) 6s. 

 net. 



The early part of this book is devoted to a dis- 

 cussion on the principles underlying transition 

 curves. The objects of a transition curve on a 

 railway are to provide a gradual increase in curva- 

 ture from zero at the point of contact of the 

 curve and the straight part of the line of rails to 

 a curvature equal to that of the central circular 

 portion of the curve, and also to provide for a 

 corresponding increase in the superelevation. 

 Special attention is given to the clothoid (or 

 Glover's spiral) A. = m\/<^, and the mathematical 

 work required to elucidate this curve is carefully 

 and clearly explained. The conditions which 

 govern the lengths of transition curves are ade- 

 quately discussed. The engineer may be called 

 upon to insert transition curves in existing lines 

 of railway and also in new lines, and for either 

 purpose he will find the explanations of the pro- 

 cedure given in this book of great service. The 

 latter half of the book is entirely taken up with 

 field exercises fully worked out, which include not 

 only the ordinary problems, but also problems in 

 compound curves and reverse curves. This part 

 is especially valuable, and cannot fail to be of use 

 to railway engineers. We can recommend this 

 book with confidence both to students of survey- 

 ing and to railway engineers. 



The New HazeU Annual and Almanack for the 

 Year 1922. By Dr. T. A. Ingram. Thirty- 

 seventh year of issue. Pp. xlvi-f-585. (London : 

 Henry Frowde, Hodder and Stoughton, Ltd., 

 1922.) 55. net. 

 The new volume of Hazell's Annual will receive 

 a cordial welcome from all who have occasion to 

 make use of reference books. It is smaller by 

 about two hundred and thirty pages than the volume 

 issued last year, the sections dealing specifically 

 with the Overseas Dominions and with foreign 

 countries having been omitted, but the omission has 

 enabled the publishers to make a handsome reduc- 

 tion in the price. We also miss several of the in- 

 teresting surveys of the progress in particular sub- 

 jects during the previous year which have hitherto 

 been included. Other features of past volumes, 

 such as the calendars, astronomical and meteor- 

 ological data for the current year, and a compilation 

 of the particulars of societies and institutions, which 

 includes most of the better-known British and 

 foreign learned societies, have been retained. A 

 large amount of educational information which 

 covers the universities, colleges, and secondary 

 schools in the British Isles has also been gathered 

 together. The volume is a. valuable book of refer- 

 ence on matters of general interest. 



