Wireless Telegraphy and Telephony

 WIRELESS TELEGRAPHY strain is thus suddenly released, it immediately returns to its former state. The sudden motion of the ether results in waves which spread out from their source in enlarging circles. Wireless telegraphy, as it is practiced to-day, is based upon the fact that a system of wires or circuits, through which high frequency oscillations are surging, becomes a source of electromagnetic waves. Various methods have been devised for making the system more efficient and capable of giving better results with a given amount of power. Fig. 7.—The simplest practical transmitter that it is possible to devise for the purpose of sending messages. Fig. 7 is a diagram showing the simplest practical trans- mitter that it is possible to devise for the purpose of send- ing messages a sufficient distance to be of any value. It would be impractical to use a static electric machine for wireless transmission, and so an induction coil or trans- former is employed. These latter instruments are for the purpose of raising electric currents of a comparatively low voltage to the high potential, where they have the power of generating high frequency oscillations.