BRANLY, ÉDOUARD. - THE INVENTION OF THE "COHERER" (RADIO-CONDUCTOR).

Variations de conductibilité sous diverses influences électriques.

(Paris, Gauthier-Villars), 1890. 4to. No wrappers. In: "Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences", Tome 111, No 21. Pp. (767-) 810. (Entire issue offered). Branly's paper: pp. 785-787.

First appearance of the paper in which Branly announced his discovery that the electrical resistance of a granular metallic conductor could drop by several orders of magnitude when excited by the electromagnetic field emitted by an electrical spark, the so-called Branly-effect.

The coherer was a key enabling technology for radio, and was the first device used to detect radio signals in practical spark gap transmitter wireless telegraphy. It became the basis for radio reception around 1900, and remained in widespread use for about ten years.

Order-nr.: 48907