Voice-frequency carrier telegraph system for cables: Polarized telegraph relays

J. J. Pilloid: The three papers, Metallic Polar-Duplex Telegraph System for Long Small-Gap Cables, Voice-Frequency Carrier Telegraph Systems for Cables and Polarized Telegraph Relays, describe two telegraph systems particularly adapted for use on long toll cables, and a relay which is an important feature of the two systems. By long toll cables we mean here cables several hundred, or a thousand or more, miles long, used for telephone or telegraph purposes.