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

To transmit signals the operator depressed the flexible brass strip (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.

The key and sounder were made by Charles T. and J. N. Chester, New York, between 1858 and 1871. Used at Melbourne Observatory.

Physical Description

Sounder with horizontal coils on brass base in leather-covered case. Key is flexible brass strip with ebonite knob. Brass components.

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