Siemens relay used at telegraph receiving stations, particularly those operating on long connecting lines. Often signals received over long lines were too weak to operate the receiving instruments directly so the relay served as a very sensitive switch to connect a local battery to the receiving instruments.

Used at Melbourne Observatory.

Physical Description

Brass baseplate on wooden base carries two horizontal coils. Brass components and screws. Four brass terminals, two on each side of wooden base. Fitted with wooden-framed glass cover.

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