Alexander Graham Bell's Telephone, 1876

Alexander Graham Bell's Telephone, 1876

Replica of Bell's 1876 telephone transmitter (microphone) consisted of a double electromagnet, in front of which a membrane, stretched on a ring, carried an oblong piece of soft iron cemented to its middle. A funnel-shaped mouthpiece directed the voice sounds upon the membrane, and as it vibrated, the soft iron armature induced corresponding currents in the coils of the electromagnet. These currents, after traversing the wire, passed through the receiver which consisted of an electromagnet in a tubular metal can having one end partially closed by a thin circular disc of soft iron. When the undulatory current passed through the coil of this electromagnet, the disc vibrated, thereby creating sound waves in the air.

Album / Science Source / New York Public Library

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3600 x 3319 px | 34.2 MB

30.5 x 28.1 cm | 12.0 x 11.1 in (300 dpi)