Die drahtlose Telegraphie

Abstract

THIS is an elementary exposition of the principles and practice of wireless telegraphy with especial reference to the systems developed by Dr. Braun. It is evidently intended to enable a practical man to become acquainted with this method without, at the same time, any attempt being made to give such a complete account as would warrant its use as a class text-book. By means of the first five chapters a reader who knows a little about the elements of electricity and magnetism will be able to appreciate the nature of electric waves and of Hertz's achievement in producing them. Then, after briefly alluding to the early system of Marconi, the writer passes on to the particular devices of Dr. Braun. The book is well and clearly written, but is in no sense a complete compendium on the subject, and the reader who derives all his knowledge from it will be inclined to think that there is only one system in the world, and that Eichhorn is its prophet. More recent methods of detecting waves by means of effects arising from hysteresis in iron are dismissed in a couple of pages, where there is no reference to Rutherford's early detector working on the same principle, while Lodge's steel-mercury-contact detector does not appear even to be mentioned, although the “Literature” appendix at the end includes the year 1903. In appendix ii. the Thomson-Kirchhoff theory of the oscillatory discharge of a condenser is given; the credit, of course, belongs to Thomson (Lord Kelvin).

Die drahtlose Telegraphie.

By Dr. Gustav Eichhorn. Pp. x + 256; numerous figures. (Leipzig: Veit and Co.) Price 5 marks.