The sending apparatus is made up of (a) a source of current, which on a submarine is the storage battery; (b) an induction coil; (c) a telegraph key; (d) a tuning coil; and (e) a condenser.
The receiving apparatus is formed of (a) a tuning coil; (b) a condenser; (c) a detector; and (d) a pair of head telephone receivers. A wireless telegraph set is shown in [Fig. 56], A and B.
Both the sending and the receiving apparatus can be connected with the aerial wire by means of what is called a throw-over switch, the purpose of which is to connect the aerial to the transmitter when messages are to be sent out and to connect the aerial to the receiver when messages are to be received. Thus only one aerial is needed.
How Wireless Works[28]—When a wireless message is sent the operator makes and breaks up the current from the storage battery into dots and dashes by means of the telegraph key.
This interrupted low pressure current flows through the induction coil and this changes it into a high pressure current which makes a jump spark. The spark in turn changes the high pressure current into high frequency currents, or electric oscillations, as they are called; and as these run forth and back over the aerial wire they set up waves in the ether which are called electric waves.
These electric waves are exactly like light waves, but they are so long that the eye cannot see them. The tuning coil and the condenser are used to give the waves whatever length the government says they must have.
Courtesy of Hilbourne and Clark Mfg. Co.
A MARINE WIRELESS INSTALLATION
When the electric waves that are sent out by the aerial of the transmitting station strike the aerial which is connected with the receiving apparatus of another ship and the operator is listening in, the waves are changed back again into high frequency currents, and these run to and fro on the aerial wire and up and down through the tuning coil, the condenser and the detector.