Telegraphy
From The Art and Popular Culture Encyclopedia
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Telegraphy (from the Greek words tele (τηλε) = far and graphein (γραφειν) = write) is the long-distance transmission of written messages without physical transport of letters, originally by changing something that could be observed from a distance (optical telegraphy). Radiotelegraphy or wireless telegraphy transmits messages using radio. Telegraphy 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).
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 that it was 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 thirty fold compared to semaphore.
Some 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. For persons who are only aware of the electrical telegraph, the reason for this name will be obscure.
Electrical telegraphs
Samuel Thomas von Sömmering constructed his electrochemical telegraph in 1809. Also as one of the first, an electromagnetic telegraph was created by Baron Schilling in 1832. Carl Friedrich Gauss and Wilhelm Weber built and first used for regular communication the electromagnetic telegraph in 1833 in Göttingen. The first commercial electrical telegraph was constructed by Sir William Fothergill Cooke and entered use on the Great Western Railway in Britain. It ran for Template:Convert from Paddington station to West Drayton and came into operation on 9 April 1839. It was patented in the United Kingdom in 1837. In 1843 Scottish inventor Alexander Bain invented a device that could be considered the first facsimile machine. He called his invention a "recording telegraph". Bain's telegraph was able to transmit images by electrical wires. In 1855 an Italian abbot, Giovanni Caselli, also created an electric telegraph that could transmit images. Caselli called his invention "Pantelegraph". Pantelegraph was successfully tested and approved for a telegraph line between Paris and Lyon.
An electrical telegraph was independently developed and patented in the United States in 1837 by Samuel F. B. Morse. His assistant, Alfred Vail, developed the Morse code signaling alphabet with Morse. America's first telegram was sent by Morse on January 6, 1838, across two miles (3 km) of wire at Speedwell Ironworks near Morristown, New Jersey. The message read "A patient waiter is no loser." On May 24, 1844, he sent the message "What hath God wrought" (quoting Numbers 23:23) from the Old Supreme Court Chamber in the Capitol in Washington to the old Mt. Clare Depot in Baltimore. This message was chosen by Annie Ellsworth of Lafayette, Indiana, later Mrs. Roswell Smith (Roswell, NM was named after her husband), the daughter of Patent Commissioner Henry Leavitt Ellsworth. The Morse/Vail telegraph was quickly deployed in the following two decades.
The first commercially successful transatlantic telegraph cable was successfully completed on 18 July 1866. Earlier transatlantic submarine cables installations were attempted in 1857, 1858 and 1865. The 1857 cable only operated intermittently for a few days or weeks before it failed. The study of underwater telegraph cables accelerated interest in mathematical analysis of very long transmission lines. The telegraph lines from Britain to India were connected in 1870 (those several companies combined to form the Eastern Telegraph Company in 1872). Australia was first linked to the rest of the world in October 1872 by a submarine telegraph cable at Darwin. This brought news reportage from the rest of the world. (Conley, David and Lamble, Stephen (2006) The Daily Miracle: An introduction to Journalism,(Third Edition) Oxford University Press, Australia pp. 305-307).
Further advancements in telegraph technology occurred in the early 1870s, when Thomas Edison devised a full duplex two-way telegraph and then doubled its capacity with the invention of quadruplex telegraphy in 1874. Edison filed for a US patent on the duplex telegraph on Sept 1, 1874 and received a US patent on 9 August 1892.
The telegraph across the Pacific was completed in 1902, finally encircling the world.
Nikola Tesla and other scientists and inventors showed the usefulness of wireless telegraphy, radiotelegraphy, or radio, beginning in the 1890s. Alexander Stepanovich Popov demonstrated to the public his receiver of wireless signals, also used as a lightning detector, on 7 May 1895. It is considered that Guglielmo Marconi sent and received his first radio signal in Italy up to 6 kilometres in 1896. Around the turn of the century, it is reported that he broadcast signals across the English Channel and in 1901, Marconi radiotelegraphed the letter "S" across the Atlantic Ocean from his station in Poldhu, Cornwall to St. John's, Newfoundland.
In 1898 Popov accomplished successful experiments of wireless communication between a naval base and a battleship. In 1900 the crew of the Russian coast defence ship General-Admiral Graf Apraksin as well as stranded Finnish fishermen were saved in the Gulf of Finland because of exchange of distress telegrams between two radiostations, located at Hogland island and inside a Russian naval base in Kotka. Both stations of wireless telegraphy were built under Popov's instructions.
Radiotelegraphy proved effective for rescue work in sea disasters by enabling effective communication between ships and from ship to shore.
See also
