Branly tripod coherer, probably made by Edouard Branly, France, 1900-1910.
Edouard Branly devised the filings coherer in about 1890 but did not use it for detecting Hertzian waves. After wireless telegraphy had been developed for practical purposes in the late 1890s, Branly invented a new form of imperfect-contact detector. The steel tripod rests on a polished steel plate. The feet are slightly oxidised, producing the imperfect contact required for detection.