November 24, 1923] 



NA TURE 



757 



of self-determination, which does not easily fit into the 

 traditional interpretation of Nature. 



I'.ntomology : with Special Reference to its Ecological 

 Aspects. By Prof. J. W. Folsom. Third revised 

 edition. Pp. vii + 502. (London: John Murray, 

 1923.) 215. net. 



ROF. Folsom's well-knowti text-book gives a clear 

 id concise account of the various aspects of ento- 

 ology, and is written with the object of meeting the 

 rowing demand for a biological treatment of the 

 ibject. The present (third) edition includes a con- 

 iderable amount of new letterpress, with the addition 

 of an opportune chapter on insect ecology, and some 

 250 titles have been added to the bibliography. Con- 

 sidering the limited size of the book (500 pp.), the 

 author has been remarkably successful in dealing with 

 his subject in a comprehensive manner. An elementary 

 treatment is, of course, only possible within this com- 

 pass. Entomology, like other branches of science, has 

 made such rapid strides during the last twelve years or 

 so, that it is almost impossible to compress a really 

 adequate work into less than 800 or 900 closely printed 

 pages. There is a great need at the present time for a 

 more advanced book, since works of an elementary 

 nature are tolerably numerous. Among the latter, 

 Prof. Folsom's book is undoubtably one of the best. 

 The author's admirably terse and lucid style is of great 

 value to the beginner, while the up-to-date biblio- 

 graphy, that is appended at the end, serves as a guide 

 to the sources where fuller information is obtainable. 



How to Build Amateur Valve Stations. By P. R. 

 Coursey. Pp. 70. (London : The Wireless Press, 

 Ltd. ; New York : The Wireless Press, Inc., 1923.) 

 IS. 6d. net. 



We can recommend this book to all who want to take 

 advantage of the latest developments of radio tele- 

 phony. The author is equally at home on the scientific 

 as well as on the practical side of the art, and experts 

 attach weight to his views. 



The very simple sets described can be trusted to 

 work admirably on days when the electrical condition 

 of the atmosphere is not very disturbed. A set for use 

 in Great Britain should have a tuning range from 300 

 up to 2700 metres. This would include the Eiflfel 

 Tower time signals, which are usually made on a wave 

 length of 2600 metres, the French " radiola " concerts, 

 which are sent on a wave-length of 1500 metres, the 

 Hague concerts on 1050 metres, the French concerts 

 from " rficole des Postes et Telegraphes " on 450 

 metres, and the British concerts broadcasted on wave- 

 rigths varying between 350 and 425 metres. Careful 

 uiid accurate descriptions are given of the components 

 "" valve receiving sets, the diagrams can be read at 



glance, and the many useful practical hints will be 



Icomed by amateurs. 





Labyrinth and Equilibrium. By Prof. S. S. Maxwell. 

 (Monographs on Exijerimental Biology.) Pp. 163. 

 (Philadelphia and London : J, B. Lippincott Co., 

 1923.) io<r. Gd. net. 



Many different views have been held as to the respec- 

 tive functions of the ampulljc, otoliths, and other con- 

 htitucnt parts of the internal ear, and any fresh evidence 



NO. 2821, VOL. II2J 



on the subject must be welcome to physiologists. 

 Prof. Maxwell seems to have attained a high degree of 

 accuracy in his experimental methods, especially in 

 dealing with the otoliths. He shows, for example, that 

 compensatory movements to rotations around the 

 longitudinal and transverse axes continue so long as 

 the otolith of the recessus utriculi remains uninjured. 

 He further shows, in the case of the ray, by mechanical 

 pressure upon the otolith in different directions, that 

 it is the displacement of the otolith and not its own 

 pressure which is the actual stimulus, and that it is 

 the direction of the displacement which determines the 

 direction of the compensatory movement. Unfortun- 

 ately, his experiments leave us completely in the 

 dark as to the reason for the existence of the three 

 semicircular canals and their highly characteristic 

 orientation. 



Radioactivity and the Latest Developments in the Study 

 of the Chemical Elements. By Prof. K. Fajans. 

 Translated from the fourth German edition by 

 T. S. Wheeler and W. G. King. Pp. xvi4- 

 138. (London : Methuen and Co., Ltd., 1923.) 

 d>s. 6d. net. 



Prof. Fajan's book is particularly addressed to 

 chemists, and it gives in a very readable form the 

 important developments in the study of radioactivity, 

 isotopes, atomic numbers, and the structure of the 

 atom which have been made in recent years. The 

 subjects are dealt with briefly, but in a very authorita- 

 tive manner, and chemical students will find the book 

 of great interest and value. There are references to 

 the literature and an index. The book is well printed 

 and illustrated. One might have wished for a little 

 more detail of experimental methods (e.g. in connexion 

 with Moseley's work, which is not described, whereas 

 Aston's apparatus is figured and explained), but in 

 the limits of his space the author has generally made 

 a wise choice of material. The numerical constants 

 in the tables of radioactive series (pp. 21-23) ^^ some 

 cases differ slightly from those adopted in the Report 

 of the International Commission on the Elements 

 (1923)- 



Geometry Practical and Theoretical, Pari Passu. By 

 V. Le Neve Foster. In 3 vols. Vol. 3 : Solid 

 Geometry. (Bell's Mathematical Series for Schools 

 and Colleges.) Pp. xiv + 423-585 + viii. (London: 

 G. Bell and Sons, Ltd., 1922.) ;^s. 6d. 



This is the third part of a work of which we have 

 already noticed the first and second parts (Nature, 

 June 10, 1922, vol. 109, p. 737). Mr. Foster continues 

 to combine the theoretical with the practical, and 

 added interest is obtained by historical references. 

 The scope of the book is indicated by the fact that it 

 deals with parallelepipeds and tetrahedra, lines and 

 planes, gradients, regular solids, and the sphere. There 

 are chapters on the mensuration of prisms, pyramids, 

 and spheres, as well as on solid angles and Euler's 

 theorem. A concluding chapter on the earth is par- 

 ticularly useful and instructive. 



Wc like this volume very much, and think it makes 

 a most useful and pleasant addition to the available 

 elementary literature on solid geometry. S. B. 



