"A Sort of Lighthouse."
"In this form it is called a transmitting valve, and we can by it generate the very powerful high-frequency to and fro or alternating electric currents in an aerial wire which are necessary in wireless telegraphy or telephony. These electric vibrations generate the electric waves which travel away through space from the aerial. The aerial wire, therefore, resembles a sort of lighthouse which is radiating invisible light.
The aerial wire, therefore, resembles a sort of lighthouse which is radiating invisible light.
The electric waves so generated can be detected by suitable receiving thermionic valves at all parts of the habitable earth.
Two Other Methods.
"There are two other methods of creating the continuous electric waves now used in wireless telegraphy. One of these is by means of a high-frequency alternator, which is a complicated kind of dynamo very different in principle from the alternators used for producing the low-frequency electric currents employed in electric lighting. Machines of this kind are installed in the great wireless stations at Long Island and at St. Assise, near Paris. Again, there is another method which makes use of an electric arc." 