Telegraph (Encyclopedia of Science)
A telegraph is any system that transmits encoded information by signal across a distance. Although the word telegraph is usually associated with sending messages by means of an electric current, it was used originally to describe a visual system for sending coded messages.
Until the telephone became a workable system, the telegraph was the standard means of communication between and within metropolitan areas in both Europe and the United States. Telephones did not make the telegraph obsolete but rather complemented its use for many decades.
Today, telegrams and telexes still use telegraphy (the sending of messages by telegraph) but are rapidly being replaced by facsimile (fax) transmissions through telephone lines. Satellite transmission and high-frequency radio bands are used for international telegraphy.
The earliest forms of sending messages over distances were probably both visual and auditory. Smoke signals by day and beacon fires by night were used by the ancient people of China, Egypt, and Greece. Drum-beats extended the range of the human voice and are known to have been used to send messages, as have reed pipes and the ram's horn.
(The entire section is 1048 words.)
Want to Read More?
Subscribe now to read the rest of this article. Plus get complete access to 30,000+ study guides!