Points from Foregoing Letters


    PHOTOGBAPHS taken with a rotating camera by Dr. T. E. Allibone and J. M. Meek show that, in laboratory spark discharges as in lightning, a pre-discharge or leader stroke traverses the whole of the inter-electrode gap before the main discharge occurs. The leader stroke begins from one or both electrodes, travelling at a rate of 20–40 km. per second (faster at reduced pressures). Its direction may be deduced from the branching of the discharge.

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    Points from Foregoing Letters. Nature 140, 811 (1937). https://doi.org/10.1038/140811b0

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