Wireless Telegraphy and Telephony

CHAPTER IX. THE WIRELESS TELEPHONE. The applications of any of the wireless telephone sys- tems thus far described are very limited, for at the best they only operate under the most favorable conditions, and then over rather limited distances. In the case of any system whereby the spéech must be transmitted over a beam of light, the great resulting limitations are that the transmis- sion can only take place in a straight line over water or clear country, and that stormy weather or a fog will inter- rupt communication. None of these objections are present, however, when recourse is had to Hertzian, or electromagnetic waves. Wireless transmission of speech has therefore followed in the wake of wireless telegraphy, and the methods and apparatus employed are very similar. Some who have followed the text closely might reason- ably ask why it would not be possible to establish wireless telephony by simply connecting a telephone transmitter in some manner to an ordinary wireless telegraph, and by directing speech into the latter, vary the strength of the oscillations emitted. Such a system, at first thought, seems very plausible, and many experimenters have devised countless methods trying to attain this result, only to meet with ultimate fail- ure. The reason is very simple. Suppose that an induction coil, having a high-speed in- terrupter, and therefore able to produce a very rapid stream 124