A telephone receiver built for the Ader company by Louis-Clément Breguet. The receiver, known as a "bull ring" type because of its shape, is made of nickel-plated brass and steel, and has a flat disk-shaped earpiece attached to a ring-shaped handle, which is also a magnet. The ring shape of the magnet was designed to create a strong magnetic field by bringing both magnet poles near the vibrating diaphragm located under the circular opening on the face of the earpiece, and increase its sensitivity.

A pair of binding posts, with knurled-edge thumb nuts, is located on the back of the receiver, near either end of the handle.

Signed on the receiver case, "Tele Recr C. ADER."

Signedon receiver case: Tele Recr C. ADER

Inscribedon receiver case: Tele Recr C. ADER

FunctionConversion of electrical signals into sound for output

Curatorial RemarksOld tag: "Alder's [sic] annunciator original

ProvenanceJefferson Laboratory, Physics Department, Harvard University

Published ReferencesThis instrument is described in: Thomas G. Hedberg, "Catalogue: Telephones, Phonographs and Related Instruments in The Collection of Historical Scientific Instruments at Harvard University." William Andrewes, Project Director (unpublished manuscript, President and Fellows of Harvard College and Thomas G. Hedberg, 1989. Fifth Draft), pp. 64-66. See also: William Henry Preece and Julius Maier, The Telephone (London: Whittaker & Co., 1889), pp.50-51.

Ader "bull ring" receiver

Ader "bull ring" receiver

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