THE SCIENCE OF THE TELEPHONE.

Thames Star, Volume VII, Issue 2635, 19 June 1877, Page 2

THE SCIENCE OF THE TELEPHONE.

The telephone, in its present form, consists of a powerful compound' permanent magnet, to the poles of which are attached ordinary telegraph coils of. insulated wire. In front of the poles, surrounded by these coils of wire,- is placed a diaphragm of iron. A mouthpiece to .converge the sound upon this diaphragm substantially completes the arrangement. As is well known, the motion of steel or iron in front of the poles of a magnet creates a Current of electricity .in -coils surrounding, the poles- of- the 'magnet,-'and - the: duration of. this /current, of electricity coincides 1 with' the duration -of- the^ motion of the steel or iron moved or vibrated in the proximity of the' magnet. When the human voice causes the diaphragm t® vibrate, electrical undulations are induced iv. the coils environing the n?agnetV,.precisely analogous to the undulations on: the air produced bys that voice. These coils' are connected with the- Jihe-wire, which may. be of. any length, provided the insulation be good. The, undulations which are induced in these coils travel through the line wire, and passing through the coils of an instrument of precisely simila: construction at the distant station, are again resolved into air undulations by the diaphragm of this instrument. The sim-. plicity of Professor Bell's system will be apparent when it is known that the* Tolatic battery is entirely dispensed with. AH that is required for communicating between the most distant points are the instruments and the telegraph wire, the latter taking the place of the speaking tube and the former that pf. the. mouthpiece. ,