All three of these devices used burning magnesium powder to provide the light for photography. This practice was widespread between the 1880s and the late 1920s, when the flashbulb was introduced. Each of these devices used different devices to ignite the powder. They are the Todd-Forrest magnesium flash lamp of 1907 (centre); the Agfa Blitz Lampe of 1910; and a flash lamp made from a First World War periscope which used a gunpowder cap to ignite the powder on the tray.
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