Metallic polar-duplex telegraph system for long small-gage cables

R. N. Nicely: In connection with the extensive toll cable program of the Bell System, it has of course, been highly desirable that satisfactory methods be made available for utilizing the cable facilities for telegraph as well as for telephone service. This has been accomplished by the development of the metallic polar-duplex telegraph system and the voice-frequency carrier telegraph system. Each of these systems is adaptable to operation under widely varying cable circuit layout arrangements and each has certain characteristics which make it particularly suitable for use in connection with different specific requirements. In actual practise, each of the systems is a valuable supplement to the other.