356 SCIENCE PROGRESS 



has become comparatively easy ; the generation of a continuous stream of high- 

 frequency oscillations by a pliotron can be effected as easily as the switching on 

 of an electric lamp. The chapter on Radiotelephony in this edition is greatly 

 extended ; but when all that has been done in Continuous Wave Telegraphy 

 and Telephony during the last four years is published, it will be necessary for 

 Prof. Fleming to amplify it still further. This book should be on the shelves of 

 all who conduct scientific work in Wireless Telegraphy ; it is an invaluable and 

 reliable work of reference for the expert, as well as a sound and trustworthy text- 

 book for the student. Wireless telegraphy and telephony have progressed in an 

 altogether remarkable way during the last few years, and it is difficult to keep up 

 with all the most recent developments. Prof. Fleming's book, however, enables 

 this to be done — it contains nearly everything a wireless telegraphist wants to 

 know. 



The Adventure of Life. By Robert W. Mackenna, M.A., M.D. 

 [Pp. xiii + 306.] (London : John Murray, 1919. Price 6^. net.) 



This is a work of popular philosophy, in which Dr. Mackenna reviews the 

 problems of life and death in a simple manner that can be understood and 

 appreciated by anyone. He clearly owes little to any previous writers, but has 

 evolved his theories from his own head while engaged on active service in France. 

 Herein lies both the strength and the weakness of his work. Its strength is in 

 its freshness and honesty of style and presentation. Its weakness is in a lack of 

 depth and of knowledge ; for he often does not understand the theories which he 

 attacks, and he produces other very ancient theories as though they were new — 

 theories long ago discarded or revised by their protagonists. The main doctrine 

 at the back of the book appears to be that all Nature is guided by intelligence, 

 working towards a purpose of beneficent character. Thus, he attacks the 

 mechanistic tendencies of physiology, without apparent knowledge of the argu- 

 ments on either side, but because it is opposed to his innate way of thought. His 

 theory requires him to show that pain is advantageous to humanity ; and he does 

 not shrink from tormenting his facts till they are forced into this Procrustean bed. 

 The pains of childbirth, for instance, may be for the purpose of strengthening 

 maternal love, which "receives a sacramental grace from suffering." In short, his 

 theory involves him in the belief in a beneficent utility of all things ; yet he 

 offers no evidence for such an opinion. The expression of a popular theory with 

 force and conviction doubtless carries with many readers greater weight than a 

 reasoned argument. Whereas the general public will probably find in this book 

 a suitable expression of their normal beliefs, it cannot honestly be said that the 

 man of science will find in it anything that concerns him. 



Hugh Elliot. 



