Telegraphy

:Telegraph redirects here. For information about the major highway in Michigan, see U.S. Highway 24. For the British newspaper see The Daily Telegraph

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Michigan - U.S. Highway 24 - The Daily Telegraph

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Telegraphy (from the Greek words tele = far and graphein = write) is the long-distance transmission of written messages without physical transport of letters, originally over wire. Radiotelegraphy or wireless telegraphy transmits messages using radio. This definition includes recent forms of data transmission such as fax, email, and computer networks in general. (A telegraph is a machine for transmitting and receiving messages over long distances, i.e. for telegraphy. The word telegraph alone generally refers to an electrical telegraph.) Wireless telegraphy is also known as CW, for continuous wave (a carrier modulated by on-off keying, as opposed to the earlier radio technique using a spark gap).

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Greek - Wire - Radio - Data - Fax - Email - Computer network - Electrical telegraph - Spark gap

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• Telegraphy messages sent by telegraph operators using Morse code were known as telegrams or cablegrams, often shortened to a cable or a wire message. Later, telegrams sent by the Telex network, a switched network of teleprinters similar to the telephone network, were known as telex messages. Before long distance telephone services were readily available or affordable, telegram services were very popular. Telegrams were often used to confirm business dealings and, unlike e-mail, telegrams were commonly used to create binding legal documents for business dealings.
• Before fax machines came into general use, wire picture or wire photo was a newspaper picture that was sent from a remote location by a facsimile telegraph. This is why many fax machines have a photo option even today.
 
Telegraphy: Optical telegraphs and smoke signals ►