December io, 1908] 



NATURE 



157 



through the medium of the latter. Aids to computa- 

 tion, such as logarithms and the slide-rule, are intro- 

 duced and largely employed in the later stages. 

 Tri>;ononietrical tables are also explained. The 

 principal feature of the work is perhaps the excellent 

 and extensive collection of practical exercises, in 

 which the student has the advantage of the author's 

 expert knowledge of the building and engineering 

 trades and of his wide experience as a teacher. The 

 subject is developed in the modern spirit, and the 

 book will be very acceptable in many quarters. 



GSie.l/.l.V PHILOSOPHICAL TEXT-BOOKS. 



Geschichle dcr Philosophic. By Karl Vorlander. 



I. Band, pp. xiv+361 ; II. Band, pp. viii + 5i2. 



(Leipzig- : Diirr'schen Buchhandlung, 1908.) Price 



3.60 marks and 4.50 marks. 

 Grundlinicn der Psychologic. By Dr. Stephan 



Witasek. Pp. viii + 392. (Leipzig : Diirr'schen 



Buchhandlung, 1908.) Price 3 marks. 

 Die Entstcliuug der wirtschajtlichen Arbeit. By Dr. 



Ed. Hahn. Pp. iv+109. (Heidelberg: Carl Winters 



L'niversitats-buchhandlung, 1908.) Price 2.50 marks. 

 "pROF. VORLANDER'S " Geschichte der Philoso- 

 -1- phie " is an attempt to compress into two small 

 volumes an account of the course of development of 

 philosophy from the earliest times to the present day. 

 When it is added that the work includes a short account 

 of the life and writings of almost every writer of any 

 importance at all in philosophy during the last five- 

 and-twenty centuries, little hope will be felt of the 

 success of the author in his attempt. It is therefore 

 of the highest credit to Prof. Vorlander that he has 

 achieved the seeming impossible, and produced a work 

 which is both eminently readable and strictly accurate. 

 He displays complete mastery of his subject through- 

 out, and a fine sense of the distinction between the re- 

 levant and the irrelevant, the latter quality being pos- 

 sibly in part due to the fact that he is a prominent 

 representative of the Neo-Kantian school, and excels 

 in the application of the critical method. The same 

 fact explains why so large a portion of the second 

 volume is allotted to a treatment of the philosophy 

 of Kant, at the expense chiefly of the description 

 of Hegelianism which follows, and which cannot but 

 be considered extremely inadequate bv any school of 

 philosophers. The last hundred pages of the book, on 

 the philosophy of the present day (since 1840), make 

 very interesting reading, and give much information 

 not to be found outside the pages of " Ueberweg- 

 Heinze "; but where so many names are mentioned, it 

 is surely most surprising to find no reference what- 

 ever to William James and the pragmatic school, 

 more particularly as the prodigious development of 

 the science of psychology during the last few years 

 and its significance for modern philosophy are dis- 

 tinctly emphasised. 



Of late vears text-books in psychology have been 

 multiplying rapidly, but no external justification is 

 needed for the publication of Dr. Stephan Witasek's 

 manual. This book is admirably arranged, clearly 

 written, and thoroughly up to date, and is probablv 

 NO. 2041, VOL. 79] 



the best and most complete introductory text-book 

 of the science which we possess at the present day. 

 In the earher, more general, chapters the author 

 argues out controversial points thoroughly, yet with- 

 out profuseness; in the later ones, on "special" 

 psychology, he gives the very latest results in the 

 experimental study of the different forms of mental 

 process. The discussion of the various possible 

 theories of the relation of mind and brain is excep- 

 tionally well done. The arguments against psycho- 

 physical parallelism and its most recent form, pan- 

 psychism, are effectively put, and although the author 

 admits that there are also serious objections to the 

 interaction theory, it is very evident that his own 

 sympathies are in this direction. The outcome of the 

 discussion would seem to be, " Either interaction or 

 a substantial soul," which, if quaint, is decidedly 

 optimistic ! 



Dr. Hahn's book is a short anthropological essay 

 on the origin of work possessing little more than an 

 academical interest. William Brown. 



OUR BOOK SHELF. 

 Tlie Radio-active Substances. By W. Makower. 



Pp. .\ii + 3oi. (London : Kegan Paul and Co., 



Ltd., 1908.) Price ^s. 

 The author's aim in writing this volume is to present 

 the chief phenomena and theories relating to radio- 

 activity in a concise and simple form. The sub- 

 ject has been competently dealt with in an ele- 

 mentary manner in other works, but it is advancing 

 rapidly, and the present work is intended to enable 

 readers to keep pace with its development. All 

 branches of the subject are treated in this book. 

 Beginning with chapters on the nature of gaseous 

 conductivity and on the methods of measurement 

 employed, the author goes on to describe the discovery 

 of the radio-active substances, the nature of the radia- 

 tions they emit, the emanations, the active deposits 

 from the emanations, and their successive trans- 

 formations. In the concluding chapters the activity 

 of substances in general and the mechanism of radio- 

 active changes are briefly discussed. 



The author has succeeded admirably in his aim of 

 giving a very full and accurate summary of the chief 

 tacts and theories in a concise form, but perhaps 

 the summary is too complete and condensed for 

 general readers. The food supplied is sound and 

 wholesome, but the general reader who has no know- 

 ledge of the subject to start with will find it difficult 

 to absorb all the nourishment supplied to him in such 

 condensed form. In some parts, notably when dis- 

 cussing the successive transformations o'f the radium 

 atom, the author has successfully made use of simple 

 analogies in presenting the results to his readers. 



In the introduction the author is guilty of stating 

 that the properties of radio-active substances have 

 necessitated a " revision of many of our conceptions 

 both in physics and chemistry." In no sense is this 

 statement defensible, and occurring in a book intended 

 in some measure for non-scientific readers, who are 

 too prone to consider every new discovery as upsetting 

 previous conceptions, it is likely to lead to the aggrava- 

 tion of an evil already sufliciently pronounced. It 

 is due to the author, however, to point out at once 

 that the above statement is an isolated one, and that 

 the book as a whole conveys no such impression, 

 showing as it does how the conceptions evolved from 

 the study of radio-activity follow as a natural sequence 



