Telegraph Key, Reversing

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Item ST 22100 Telegraph Key - Reversing, Mebourne Observatory, Elliott Bros., London, England, 1890s

Summary

Reversing telegraph key used for the transmission of signals in the electric telegraph system.

This type of key was used in conjunction with long submarine telegraph cables which distorted electrical signals so that the normal on-off pulses used in land telegraphy to mark the dots and dashes of Morse code would not work. Instead, the direction of flow of signal current was changed so that current flowing in one direction signalled a dot and in the other direction a dash. The reversing key used two separate keys, one for each direction of current flow.

At the receiving end the sequence of current pulses were displayed as a wavy line on a moving paper tape which could be interpreted by the operator .

Made by Elliott Bros, London. Used at Melbourne Observatory.