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SCIENCE 



[N. S. Vol. XXVI. No. 676 



the Berlin Convention, which imposes an 

 obligation on all commercial stations to in- 

 tercommunicate without regard to the make 

 or system of transmitting apparatus em- 

 ployed. I am of the opinion that there 

 Avill be no difficulty in carrying this into 

 effect provided that the stations using the 

 spark method send out long trains of 

 waves, as they should do to obtain syntonic 

 woi'king, which is also called for by the 

 Berlin Convention. 



An extremely interesting development 

 which is now progressing rapidly owing to 

 the possibility of producing continuous 

 oscillations by the are method is wireless 

 telephony. Suppose that we can vary the 

 intensity of the oscillations in a manner 

 corresponding with the vibrations of the 

 air which constitutes sound and speech, 

 then we should obtain at the receiving sta- 

 tions a train of Hertzian waves whose 

 amplitude varies in a corresponding way; 

 by allowing these waves to act on a tele- 

 phonic receiver which is sensitive to the 

 intensity of the waves we shall obtain in 

 the telephone a reproduction of the sounds. 

 This has actually been carried into effect 

 by employing an ordinary microphone to 

 modify the current through the transmit- 

 ting arc so as to vary the intensity of the 

 oscillation current produced, and by em- 

 ploying what is known as a point-detector 

 and a telephone at the receiving station. 



Another method which may be used con- 

 sists in causing the microphone to vary the 

 frequency of the oscillations of the gen- 

 erator, and by arranging the receiver so 

 that it is '.more or less strongly affected 

 according to the frequency of the received 

 waves. 



I am informed that such good results 

 have already been obtained on the experi- 

 mental stations for wireless telephony that 

 it is proposed to equip stations at Oxford 

 and Cambridge for the further perfecting 

 of this application. 



It is greatly to be desired that wireless 

 telephony may develop rapidly, as it seems 

 to me that for the purpose of communicat- 

 ing with ships wireless telephony wiU have 

 great advantages over wireless telegraphy. 



I am deeply indebted to Mr. Colson for 

 all the facilities that he has placed at my 

 disposal, and to his engineers for their as- 

 sistance, which has enabled me to carry out 

 the experiments in the lecture ; and I have 

 also to thank the tramway department for 

 the special supply of current. 



W. DUDDELL 



SCIENTIFIC BOOKS 

 Experimental Zoology. By Thomas Hunt 



Morgan. New York, The Macmillan Co. 



1907. Pp. xii + 454. 



The field of experimental zoology has of 

 late years been greatly extended and includes 

 problems of widely different nature. The 

 title of this book justifies the expectation of 

 finding between the covers an attempt to bring- 

 together the results of experiment in the vari- 

 ous fields and at the same time raises in the 

 mind of the reader the question as to how the 

 author has found it possible to treat ade- 

 quately in some four hundred and fifty pages 

 the data and problems involved. This ques- 

 tion is answered in part, however, by the 

 preface and table of contents, from which it 

 appears that experimental embryology, regula- 

 tion and animal behavior are not included 

 within the scope of the book because, as the 

 author states, they have recently received full 

 consideration and, furthermore, would require 

 too much space to be included in a single 

 volume. 



In short, the book treats primarily of those 

 subjects and problems of experimental zoology 

 which have not been considered in other books. 

 This limitation necessarily defines its scope in 

 a somewhat arbitrary manner and without 

 relation to the problems involved. It is a fair 

 question, therefore, whether the subject-matter 

 of the book justifies its title: it would seem 

 that some less inclusive title would have been 

 more fitting. 



In the preface the author states that 



