CHAPTER I. INTRODUCTORY.
Being desirous of keeping this book as far as possible within the limits prescribed by the title, it is not possible to go deeply into the theory of the propagation of electric waves, but at the same time it is not deemed advisable to plunge suddenly into the construction of wireless apparatus without giving some explanation of the underlying principles.
If the reader desires information upon this subject he is referred to Fleming's "Electric Wave Telegraphy" or the same author's "Elementary Manual of Radio-telegraphy and Radio-telephony."
The explanations given in this chapter do not involve any actual theory of the transmission and reception of electric waves. They are merely intended to show the train of actions which take place and may be observed in a physical sense. With this purpose in view, several references have been made to simple hydraulic apparatus and an analogy drawn to render the explanation clearer.