English: "63,383. Telephonograph after Poulsen, for permanently fixing and conveniently repeating a telephonic conversation, Figure (cf. E. T. Z., 1901, p. 57, 181; Drudes Annalen d. Physik, 3, 1900, p. 754), with a microphone for transmitting, two telephones for receiving, and the necessary cells, also two steel discs and a demagnetizing device.

The fluctuations in a current produced by a microphone are carried through a magnetizing coil, which is guided over a hardened steel plate in a spiral line, in a similar manner as employed in gramophones. The fluctuations in magnetization of the steel plate, which are permanently recorded, suffice to induce currents in the coil of the magnet when the latter is again guided over the steel plate. These currents provide, in the telephone, an accurate and surprisingly clear reproduction - which can be repeated at will - of the sounds originally conducted into the microphone."

Max Kohl A.G. : Physical Apparatus. Price List No. 50, Vols. II and III. Chemnitz, n.d. 1911, p. 1057.