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Telegraph Systems

For many years telegraph messages were sent by hand-operated keys. Modern telegraph systems, however, now employ the latest developments in circuits, electromechanical apparatus, and electronics.1 Many interesting telegraph systems have been developed. The following pages will consider certain of these, and will discuss the recent developments that seem destined to revolutionize the industry. The presentation will be confined to systems using open-wire lines and cables. Radio telegraph methods will be discussed in Chapter 13.


Last Update: 2011-05-27