... messages over the telegraph wires of this country, it remains a noteworthy fact that approximately 90 per cent of the traffic is still handled by Morse operators on simplex, duplex, and quadruplex circuits. The original Morse telegraph system, anbsp;...
|Title||:||Telephones and telegraphs and municipal electric fire-alarm and police patrol signaling systems|
|Author||:||United States. Bureau of the Census, William Mott Steuart, John W. Curry, William A. Countryman|