Carrier current systems

The paper discusses the general principles of operation of the carrier current telephone and telegraph system developed by the International Standard Electric Corporation, and installed in various parts of the world, more particularly with reference to Australia. Some discussion is given of the economics of the question, and illustrative examples of costs are shown. In conclusion, it is pointed out that four copper wires used with carrier equipment can provide for nine telephone and four telegraph channels, or, used completely for telegraph channels, can handle a total of 43,680 words per minute.