Portable telegraph key and sounder. Used by personnel working on telegraph lines in the field to transmit and receive messages.

To transmit signals the operator depressed a pivoted metal lever (the key) to complete an electric circuit and transmit current along the telegraph line. Releasing the key broke the circuit and cut off the current. Letters and numbers were represented by a sequence of short and long current pulses, transmitted according to a defined code. The most widely used code was generally known as "Morse code".

When receiving signals, the incoming current pulses energised the coils of the receiving instrument, or "sounder". The operator interpreted the signals by listening to the sounds made by the sounder mechanism.

Physical Description

Ebonite base. Straight brass key with ebonite knob. Two horizontal coils with ebonite covers. Brass screw terminals. Base fitted with small circular magnetic compass.

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