June 22, 191 1] 



NATURE 



:)d3 



Lyer illusion describes an extremely interesting ex- 

 ample of the success with which careful psychological 

 experimentation, supplemented by exact measurement, 

 can analyse out the various hidden factors involved 

 in the production of an optical illusion. Colour vision 

 and experimental aesthetics are treated in a way which 

 cannot fail to interest the ordinary educated reader. 

 But the parts of the book which deserve to be singled 

 out as of particular interest for applied science, educa- 

 tional or medical, and as a really masterly description, 

 in a small compass, of work perhaps most character- 

 istic of modern psychological advance, are the chapters 

 on memory and on mental tests and their uses. 

 Readers of the author's larger text-book of "Experi- 

 mental Psychology," will recognise in the former a 

 condensation of the excellent account of the subject in 

 that book. The discussion of mental tests includes 

 clear instructions as to the mqthod to be employed in 

 applying certain of the more important of them, and 

 gives a summary of many of the results, which will be 

 found exceedingly useful to readers who have not the 

 time or the facilities for referring to the original pub- 

 lications. Such questions as the effect of alcohol and 

 other drugs upon muscular work and fatigue, the 

 standardisation of intelligence, and the correlation of 

 mental abilities one with another, will all be found 

 adequately treated. 



The book contains a bibliography and index, and 

 is artistically bound and very clearly printed. 



W. B. 



Grundzuge der Matheniatisch-Physikalischen Akiistik. 



by Prof. A. Kalahne. Teil i., pp. vii+130. 



(Leipzig and Berlin : B. G. Teubner, 1910.) Price 



3.20 marks. 



This little work forms an excellent introduction to 

 the mathematical basis of acoustics. Though using 

 the calculus freely wherever needed, including differ- 

 ential equations, the treatment is simple and full, the 

 analysis being illustrated by numerical examples and 

 corresponding diagrams drawn to scale. The present 

 part (being the first of two) is divided into seven 

 chapters. Of these the first is devoted to vibrations 

 and waves in general, the second to Fourier's series 

 and harmonic analysis, while the third deals with the 

 musical intervals of the scale, and kindred topics. 

 Then, the subject being introduced, its formal de- 

 velopment follows. The fourth and fifth chapters 

 treat the vibrations of a particle, undamped and 

 damped respectively. The sixth chapter deals with 

 resonance and forced vibrations, the concluding chap- 

 ter extending the treatment to systems of more de- 

 grees of freedom and their coupled vibrations. Per- 

 haps to the English reader the most valuable features 

 of the work are the tables and the curves giving con- 

 crete expression to the numerical illustrations. The 

 growth of forced vibrations and the sharpness of 

 resonance are verv well shown, and may serve as a 

 reminder of the electrical work of V. Bjerknes, Zen- 

 neck, and others in Hertzian waves and wireless tele- 

 graphy. E. H, B. 



Phvsical Measuretnents. By Prof. A. W. Duff and 

 Prof. A. W. Ewell. Second edition, revised and 

 enlarged. Pp. x + 258. (London: J. and A. 

 Churchill, 1911.) Price ys. 6d. net. 

 This book is intended by the authors for students 

 who have already completed an elementary course of 

 practical physics. It is not, however, a treatise on 

 methods of physical measurement, but the authors 

 have described upwards of seventy typical experiments 

 of an advanced and modern character. While the 

 descriptions of these experiments are usually applic- 

 able to apparatus in general, they are in many cases 

 NO. 2173, VOL. 86] 



somewhat sparse in detail. Thus, for example, in 

 Expt. Ixiii., "Strength of a Magnetic Field by Bis- 

 muth Spiral," no remarks are made on the necessity 

 of maintaining the temperature of the spiral constant, 

 which is of primary importance if trustworthy results 

 are to be obtained by this method. These defects are, 

 however, partially remedied by the references given 

 by the authors at the commencement of each experi- 

 ment to more advanced treatises and sources where 

 the subject under investigation is dealt with more 

 exhaustively. Such well-known text-books as Kohl- 

 rausch, Watson, and Stewart and Gee figure con- 

 spicuously in this respect. The authors consider that 

 the books and papers referred to in this way should 

 be consulted by the student before commencing the 

 experiment. A few questions are usually appended 

 to each experiment bearing upon its subject-matter, 

 At the end of the book are tables of logarithms and 

 physical constants. 



In the diagram on p. 70 (hypsometer) surely it is 

 better to connect the pressure gauge directly with the 

 inner cylinder of the hypsometer. The following ex- 

 perirnent, No. xiv., p." 71, would have been better 

 described as " Linear Coefficient of Expansion " and 

 not "Temperature Coeflficient of Expansion." 



If the book is used in conjunction with the refer- 

 ences it will prove of value to the student of physics. 



Unstcrblichkeit : Eine Kritik der Beziehungen zxvischen 



Naturgcschenen und menschlicher Vorstellungswelt. 



By Hermann Graf Keyserling. Zweite Auflage. 



Pp. iv + 285. (Munich: J. F. Lehmann, 1911.) 



Price 5 marks. 

 In the review of the first edition of this work (N.vruRE, 

 vol. Ixxxii., p. 5, November 4, 1909) it was pointed 

 out that the fundamental idea was that of faith as a 

 permanent and essential constituent of human move- 

 ment along the lines both of thought and of action. 

 In the present edition, this is the single point of view, 

 and the concluding chapters of the original work, 

 amounting to about sixty pages, are now included 

 in the author's " Prolegomena zur Naturphilosophie." 

 The work is rich in thought and represents a note- 

 worthy contribution of a naturalist to the human 

 concept of immortality. 



Elementary Regional Geography. Europe and the 



Mediterranean Region. By J. B. Reynolds. Pp. 



viii+184. (London : A. and C. Black, 1911.) Price 



IS. 4d. 

 Cambridge County Geographies. Berkshire. By 



H. W. Monckton. (Cambridge : University Press, 



1911.) Price 15. 6d. 

 Maps and other illustrations take the most prominent 

 place in Miss Reynolds's little book on Europe. The 

 volume should form a useful introduction to the sub- 

 ject for young people, but it would have been more 

 suitable for this purpose if the children had been 

 provided with more work to do for themselves. 



Mr. Monckton 's book on "Berkshire" is a worthy 

 addition to an interesting series; it has all the good 

 qualities noticed in connection with its companion 

 volumes. 



Space and Spirit. A Commentary upon the Work 

 of Sir Oliver Lodge, entitled "Life and Matter." 

 Bv R. A. Kennedy. Second edition. Pp. 64. 

 (London : Charles Knight and Co., Ltd., 1911.) 

 Price 15. 6d. net. 

 The first edition of this booklet was reviewed at some 

 length in our issue of February 24, 1910 (vol. Ixxxii., 

 p. 486). The new edition contains some further con- 

 tributions by way of appendix, and a new list of 

 definitions. 



