fulchronograph

noun

ful·​chronograph

(ˈ)fu̇l,

¦fəl+

: a lightning-recording device that consists of a revolving aluminum disk having on its rim several hundred steel fins which, as they pass successively every forty-millionth of a second between two coils carrying the surge current of a lightning stroke, become proportionately magnetized and register the duration and intensity of the strokes

Word History

Etymology

Latin fulgur lightning (from fulgēre to shine, flash) + English chronograph

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