The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 59
mpany upon all their systems, and in order that the working of boththe trunk and local systems may be apprehended it is necessary to discussthis apparatus. The object gained is to reduce the battery necessary atthe subscribers offices. The generator provides alternating currents inretun for the… … ^~T ^^ \^ _^ ^ Figure 34. magnetic by induction from a permanent magnet N S (Figure 34). A thinsteel rod carrying a brass ball is screwed into this armature at rightangles to it, and plays between the two bell domes L and M. The diagramsufficiently illustrates the mechanical construction. The south…
Telephone · Postal service
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