telephonograph

Century Dictionary and Cyclopedia

1. n. An apparatus devised by Valdemar Poulsen, of Copenhagen, for the recording and subsequent reproduction of musical tones or of speech transmitted through a telephone. It differs from other phonographic devices in that the record is made by the local transverse magnetization of a steel tape or wire which passes between two electromagnets placed in the electric circuit of the transmitter. These local regions of magnetization correspond to the mechanical impressions in the recording surface of the ordinary phonograph. When the tape or wire is passed again between the electromaguets in the same direction and at the same speed, it in turn induces cnrrents in the circuit of which the electromagnets form a part and these currents produce movements of the telephonic disk. The sounds uttered by the disk in consequence of the motions are a faithful reproduction of those which actuated the disk in the process of recording and are free from the disturbances due to mechanical contact between the stylus and the indented surface of the cylinder or record-disk of the usual phonographic apparatus. The record, moreover, is free from deterioration by wear and may be utilized for reproduction almost indefinitely. A record may however be completely expunged by demagnetization of the tape or wire, which is then ready for further use. In a later and somewhat modified form the apparatus is known as the telegraphone. Also magneto-phonograph. Smithsonian Rep., 1901, p. 308.
2. n. A device for making a permanent record of a message received by telephone.