Mr.Carty began installing the metallic circuit in his lines that is, he used wire, instead of the ground, to complete the circuit.

As a result of this improvement the telephone was immediately cleared of these annoying interruptions.

Mr.Carty, who is now Chief Engineer of the American Telephone and Telegraph Company, and the man who has superintended all its extensions in recent years, is one of the three or four men who have done most to create the present system.
Another is Charles E.Scribner, who, by his invention of that intricate device, the multiple switchboard, has converted the telephone exchange into a smoothly working, orderly place.

Scribner's multiple switchboard dates from about 1890.

It was Mr.Scribner also who replaced the individual system of dry cells with one common battery located at the central exchange, an improvement which saved the Company 4,000,000 dry cells a year.