Sidelever Spark Key

This is a Marconi Sidelever Spark Key or “Guillotine” Spark Key, as it was sometimes called for the appearance of the long lever on the side of the key. The key was used for keying a wireless telegraph spark transmitter on and off. A key similar to this was used on the Titanic when she sank in 1912. The sidelever or guillotine (e.g. the long lever on the side of the key) was needed to disable the transmitter keying circuit if the spark key contacts became welded together by the high currents being switched during operation. If this happened the transmitter would be keyed continuously. Lifting the lever up would disable the keying and shut the transmitter down. The sidelever was also used to disable accidental keying when the transmitter was not in use.

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