REVIEWS 503 



scrappy, while the style of the whole book would have been improved if 

 more careful revision of these notes had been made before putting them 

 together. Particularly is this noticeable in the Introductory Chapter — 

 and the more unfortunately so since it is from the earlier chapters that 

 the reader often unconsciously forms an opinion as to the merits of the 

 book as a whole. In a volume that is in any case a bulky one, the reader 

 does not wish to be wearied by unnecessary (and almost verbatim) repetitions. 



But to turn now to a more detailed resume of the scope of the book — 

 the Introductory Chapter gives a brief account of the chief landmarks in the 

 development of the quenched spark " system." Next follows the com- 

 mencement proper of the technical description of the wireless apparatus 

 itself, and devoting himself entirely to his own " system," the author plunges 

 straight into the theory of h.f. oscillation production by condenser dis- 

 charges, and the theory of quenching. In Chapters III to VIII details are 

 given of the apparatus used for transmission and reception as manufactured 

 by the Telefunken Company (the Gesellschaft fiir drahtlose Telegraphic), 

 and Messrs. Siemens Bros. These descriptions are accompanied by many 

 excellent illustrations, showing not only the external appearance of the 

 instruments, but details of their construction as well. 



With Chapter IX begins a section of the book devoted to the practical 

 applications of quenched spark apparatus for land and ship installations, 

 their applications in warfare and in aeronautics. These chapters are also 

 liberally interspersed with good photographic illustrations, which add 

 greatly to the value of the book to the student unfamiliar with the appear- 

 ance of such commercial apparatus. The care and maintenance of quenched 

 spark apparatus is dealt with in detail in Chapter XIV — a chapter which 

 is evidently written almost entirely for the wireless operator. 



Chapters XIII and XV are the only two which deal to any serious extent 

 with apparatus other than of the Telefunken type — the former discusses 

 continuous wave telegraphy and telephony (including valve, arc, and high- 

 frequency alternator apparatus), while the latter sets out some theoretical 

 ideas as to the mechanism of wave propagation and the variations in direc- 

 tional effects and in the intensity of the received signals. 



The work, covering as it does nearly five hundred pages, is of too bulky 

 and too comprehensive a nature for detailed criticism of its contents beyond 

 the general remarks as to its scope that have already been made. In keeping 

 with the aim of the book the bulk of the bibliographical references given 

 at the end of each chapter are to German works or articles, and this limita- 

 tion detracts somewhat from the general usefulness of the volume to the 

 student, since to one unacquainted with other work in this field an entirely 

 false impression might be given. Since these references are presumably 

 intended for the edification of readers of the student class, it is a great pity 

 that more care has not been taken in their compilation and checking. The 

 colloquial and often inaccurate abbreviations of these references sometimes 

 used in conversation should also scarcely find a place in print in a volume 

 of this character. It is to be hoped that in future editions these and other 

 blemishes and inaccuracies may be rectified, and that the author will include 

 more up-to-date information with regard to other types of apparatus when 

 comparing them with those of the quenched spark type. 



The general appearance of the book is excellent with the exception of 

 the mathematical portions, where there is some lack of consistency in the 

 symbols used, and between the symbols and the diagrams to which they 

 refer. The well-known internationally recognised conventions with regard 

 to such symbols might have been adhered to with advantage, and in par- 

 ticular, after perusing Chapter II one feels tempted to suggest that in this 

 connection the author might profitably have studied some of the English 

 scientific publications which he apparently professes to despise. 



