Telegraph lightning arrester, used to protect telegraph equipment from damage due to lightning strikes on the telegraph line.

At a telegraph station, the lightning arrester is positioned in the wiring circuit between the telegraph line itself and the various instruments at the station, such as the relay, the sounder, the register and the telegraph key. The arrester provides an alternative path to earth across an air gap which the high lightning-induced current jumps but which blocks the normal telegraph line current.

The lightning arrester could not be guaranteed to provide absolute protection of the telegraph station instruments and recommended operational practice during severe thunderstorms was, where possible, to cut the station out of the line completely.

Physical Description

Three vertical brass plates on a marble base. The two outer plates are fitted with sets of points directed towards but not touching the centre plate. Brass fittings and terminals.

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