Fature Terrors of Broadcasting Rapro ron Evenysopy.—By A. ©. Its carboura—Methuen, 1922. 7/6 net.
This ig an English edition of an American book written by the Editor of the "Scientific American." It has been altered somewhat to render it more easily understood of the Englishman and also includes descriptions of recent practice in England, these changes having been made by an English editor, Mr. Smith-Rose, of the National' Physical Laboratory.
The word "radio," as perhaps most people now know, is technical slang for wireless communication, and this book fully justifes its title. Without being very technical it gives all the essential information which an actual practical amateur requires and at the same time will provide any one who is merely interested in the subject with readable data.
It opens with a good general description of the principles of the transmission of the electromagnetic or "Hertzian" wave which are the whole basis of wireless practice, and then gives a short but sufficient glossary of the main™ technical terms. Next comes a description of the most recent practice in the United States and Great Britain, including the "broadcasting" of news and music in 1922. The bulk of the book is devoted to a good and fairly simple description of the instruments used and concludes with sections on the practical application both by professionals and amateurs of radio to telephony, telegraphy and control and direction finding.
As in all such books of recent date, one is more and more impressed with the extraordinary value of the thermionic or triode valve, formerly termed an " audion." While it is possible to operate without it by means of coherers or lerystals, it is this device which has so increased sensitiveness of the receiving apparatus, that the certainty of fairly good results has risen to a degree which compels general attention, By "banks" of such valves, feeble currents which will scarcely, if at all, actuated a telephone can be supplemented until they will work loud speaking telephones capable of filling large halls with sound. One dreads to think of the terrific power which lies ready to the hand of the demagogue in this process of broadcasting. There is no reason to doubt that within a very few years a pndlic orate, will be able simultanvous!y to reach audiences numbering hundreds of thousands and, while a big trumpet however nicely camouflaged will doubtless have a smaller psychviogical effect than the personal contortions of the speaker, his soul-melting periods will penetrate the minds of every individual assembled in the various public halls served by these instruments, Turning to the ordinary use of the wireless telephone, it appears that the range is still limited to a few hundred miles and that privacy is not yet fully assured. Yho combination of wireless links with ordinary telephonic lines is well advanced.
The book contains some brief references to the wireless control of ships, motors and aeroplanes, which has been much to the fore in recent experimental war work, and also to direction finding for navigation purposes, At the end there are some oxcellent and practical directions for the construction of simple seta and also some notes'as to the future possibilities of the radiotelephone.
could have wished that something were given as to the wireless transmission of power, of which the cun's light is the best example, and also of 1 and exhibition possibilities of the high frequency' currents which are used in all wireless practice. English books are peculiarly deficient in their references to both these matters.
This work can be strongly recommended to all perers smurreaied in the subject.
Text read from the printed page and cleaned; old type leaves the occasional error.