John Moyle – Major Fuller and the Fortunes of War

Author: John Moyle, University of Leeds

Title: Major Fuller and the Fortunes of War


Early in World War I, it became apparent that the Germans were “tapping” British front line communications. These communications were those being made over land lines by telegraphy and telephony. This wire-tapping was not by direct contact but by laying lines parallel and in close proximity to British lines. Mutual inductance caused any change in electrical current in the British line induced a similar change in the parallel German conductor. The induced current varied with the rate-of-change of current, its amplitude and the closeness of the German sensing wire. Signals from Morse/sounder, Morse/buzzer and Telephony were detectable. Major Fuller invented his Fullerphone which enormously reduced the line electric current required for telegraphy to the extent that it became virtually impossible to tap by the parallel line induction method. But was it Fuller’s invention? Earlier very similar circuits by telegraph engineers in the Netherlands (1880s), France (1887), USA (1894) and others were developed but with different telegraphic applications in mind. Whose intellectual property was the Fullerphone? Did Fuller take advantage of the exigencies of war to patent a new application for that which was the IP of others? He also gained lucrative advantage, fame and a prestigious award.

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