A telegraph is a machine for transmitting and receiving messages over long distances, i.e., for telegraphy. The word telegraph alone now 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.Fact: date=September 2008

A telegraph message sent by a telegraph operator (or telegrapher) using Morse code or a printing telegraph operator using plain text was known as a telegram or cablegram, often shortened to a cable or a wire message. Later, a telegram sent by the Telex network, a switched network of teleprinters similar to the telephone network, was known as a telex message.

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 email, telegrams were commonly used to create binding legal documents for business dealings.Fact: date=September 2008

A wire picture or wire photo was a newspaper picture that was sent from a remote location by a facsimile telegraph.

Optical

The first telegraphs came in the form of optical telegraphs, including the use of smoke signals and beacons, which have existed since ancient times. A semaphore network invented by Claude Chappe operated in France from 1792 through 1846. It helped Napoleon enough to be widely imitated in Europe and the U.S. The last commercial semaphore link ceased operation in Sweden in 1880.

Semaphores were able to convey information more precisely than smoke signals and beacons, and consumed no fuel. Messages could be sent at much greater speed than post riders and could serve entire regions. However, like beacons and smoke signals, they were dependent on good weather to work. They required operators and towers every 30 km (20 mi), and could only accommodate about two words per minute. This was useful to governments, but too expensive for most commercial uses other than commodity price information. Electric telegraphs were to reduce the cost of sending a message thirtyfold compared to semaphores.

Elevated locations where optical telegraphs were placed for maximum visibility were renamed to Telegraph Hill, such as Telegraph Hill, San Francisco, and Telegraph Hill in the PNC Bank Arts Center in New Jersey.

Electrical telegraphs

Main: Electrical telegraph One very early experiment in electrical telegraphy was an electrochemical telegraph created by the German physician, anatomist and inventor Samuel Thomas von Sömmering in 1809, based on an earlier, less robust design of 1804 by Catalan polymath and scientist Francisco Salvá i Campillo. Both their designs employed multiple wires (up to 35) in order to visually represent most latin letters and numerals. Thus, messages could be conveyed electrically up to a few kilometers (in von Sömmering's design), with each of the telegraph receiver's wires immersed in a separate glass tube of acid. As an electrical current was applied by the sender representing each digit of a message, it would at the recipient's end electrolyse the acid in its corresponding tube, releasing a stream of hydrogen bubbles next to its associated letter or numeral. The telegraph receiver's operator would visually observe the bubbles and could then record the transmitted message, albeit at a very low baud rate. Jones, R. Victor Samuel Thomas von Sömmering's "Space Multiplexed" Electrochemical Telegraph (1808-10), Harvard University website. Attributed to "Semaphore to Satellite" , International Telecommunication Union, Geneva 1965. Retrieved 2009-05-01