Semi-automatic telegraph key, made by the Mecograph Company of Cleveland, Ohio, U.S.A.

The key mechanism caused the "dot" signals of the Morse code to be transmitted automatically while the operator generated only the longer "dash" signals. Also the key moved horizontally rather than vertically as in conventional telegraph keys. These two features made for faster transmission of signals and eased the stress on the operator's hand and arm, reducing the incidence of the occupational affliction known as "telegrapher's paralysis" or "glass arm".

Physical Description

Brass components with ebonite knobs, mounted on grey-painted steel base.

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