Electric Light Wires as Telephonic Circuits

Abstract

I WISH to put on record the following method of using electric lighting wires as telephonic circuits. I was requested some time ago to try to localise a fault in an electric light main, by means of a certain form of inductor used in conjunction with a telephone but not connected to the main. While using it, it occurred to me that probably the main might be used instead of a telephone wire. My first experiments were not productive of good results, as a small fraction of the Company's current passed continuously through the telephone. In October 1897, I placed $\frac{1}{3}$ microfarad condensers in my telephone circuit at each end; these stopped the current, but in no way reduced the telephonic effects. If the note given out by virtue of the rotation of the armature of the dynamo is great, it can be very greatly reduced by placing an inductively wound resistance in the circuit.