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Time pencils were fuzes timed by acid corroding a thin wire , when the wire broke a spring forced a pin onto a percussion cap exploding a small charge.

Timing could be erratic in different temperatures, a colour code denoted the time period of each fuze.

Used mainly by resistance movements in various Countries.
The items shown are colour time code Green.

Your comments:

  • Actor David Niven used these type of timing pencils in the movie "Guns of Navarone". His contained fulminate of mercury. David Niven actually fought throughout WWI in various units.
    .......... Kelly Altenhofen, United States, 3rd of October 2018

  • The time pencils were always used in pairs as the reliability of the fuze was a bit erratic. Issued to the British Underground Resistance known as the Auxiliary Units.
    The time pencils operated differently in summer to winter. Times were longer in cold weather

    Red 1/2 hour summer 3/4 hour winter
    White 11/2 hours summer 21/2 hours winter
    Green 5 hours summer 6 hours winter
    Yellow 10 hours summer 18 hours winter
    Blue 20 hours summer 30 hours winter
    Black 10 mins only used for training
    .......... STEPHEN LEWINS, MORPETH, 8th of November 2014

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