Telegraphy(Redirected from Telegraph)
Telegraphy (from Ancient Greek: τῆλε, têle, "at a distance" and γράφειν, gráphein, "to write") is the long-distance transmission of textual or symbolic (as opposed to verbal or audio) messages without the physical exchange of an object bearing the message. Thus semaphore is a method of telegraphy, whereas pigeon post is not.
Telegraphy requires that the method used for encoding the message be known to both sender and receiver. Many methods are designed according to the limits of the signalling medium used. The use of smoke signals, beacons, reflected light signals, and flag semaphore signals are early examples.
In the 19th century, the harnessing of electricity led to the invention of electrical telegraphy. The advent of radio in the early 20th century brought about radiotelegraphy and other forms of wireless telegraphy. In the Internet age, telegraphic means developed greatly in sophistication and ease of use, with natural language interfaces that hide the underlying code, allowing such technologies as electronic mail and instant messaging.
A "telegraph" is a device 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, transmission of messages over radio with telegraphic codes.
Contrary to the extensive definition used by Chappe, Morse argued that the term telegraph can strictly be applied only to systems that transmit and record messages at a distance. This is to be distinguished from semaphore, which merely transmits messages. Smoke signals, for instance, are to be considered semaphore, not telegraph. According to Morse, telegraph dates only from 1832 when Pavel Schilling invented one of the earliest electrical telegraphs.
A telegraph message sent by an electrical telegraph operator or telegrapher using Morse code (or a printing telegraph operator using plain text) was known as a telegram. A cablegram was a message sent by a submarine telegraph cable, often shortened to a cable or a wire. Later, a Telex was a message sent by a Telex network, a switched network of teleprinters similar to a telephone network.
A wire picture or wire photo was a newspaper picture that was sent from a remote location by a facsimile telegraph. A diplomatic telegram, also known as a diplomatic cable, is the term given to a confidential communication between a diplomatic mission and the foreign ministry of its parent country. These continue to be called telegrams or cables regardless of the method used for transmission.
Passing messages by signalling over distance is an ancient practice. One of the oldest examples is the signal towers of the Great Wall of China. In 400 BC, signals could be sent by beacon fires or drum beats. By 200 BC complex flag signalling had developed, and by the Han dynasty (200 BC–220 AD) signallers had a choice of lights, flags, or gunshots to send signals. By the Tang dynasty (618–907) a message could be sent 700 miles in 24 hours. The Ming dynasty (1368–1644) added artillery to the possible signals. While the signalling was complex, for instance, different coloured flags could be used to indicate enemy strength, only predetermined messages could be sent. The Chinese signalling system extended well beyond the Great Wall. Signal towers away from the wall were used to give early warning of an attack. Others were built even further out as part of the protection of trade routes, especially the Silk Road.
Signal fires were widely used in Europe and elsewhere for military purposes. The Roman army made frequent use of them, as did their enemies, and the remains of some of the stations still exist. Few details have been recorded of the signalling systems and the possible messages. One of the few for which details are known is a system invented by Aeneas Tacticus (4th century BC). Tacitus's system had water filled pots at the two signal stations which were drained in synchronisation. Annotation on a floating scale indicated which message was being sent or received. Signals sent by means of torches indicated when to start and stop draining to keep the synchronisation.
None of the signalling systems discussed above are true telegraphs in the sense of a system that can transmit arbitrary messages over arbitrary distances. Lines of signalling relay stations can send messages to any required distance, but all these systems are limited to one extent or another in the range of messages that they can send. A system like flag semaphore, with an alphabetic code, can certainly send any given message, but the system is designed for short-range communication between two persons. An engine order telegraph, used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and very simple message set. There was only one ancient signalling system described that does meet these criteria. That was a system using the Polybius square to encode an alphabet. Polybius (2nd century BC) suggested using two successive groups of torches to identify the coordinates of the letter of the alphabet being transmitted. The number of said torches held up signalled the grid square that contained the letter. The system would have been very slow for military purposes and there is no record of it ever being used.
An optical telegraph, or semaphore telegraph is a telegraph consisting of a line of stations in towers or natural high points which signal to each other by means of shutters or paddles. Early proposals for an optical telegraph system were made to the Royal Society by Robert Hooke in 1684 and were first implemented on an experimental level by Sir Richard Lovell Edgeworth in 1767.
During 1790–1795, at the height of the French Revolution, France needed a swift and reliable communication system to thwart the war efforts of its enemies. In 1790, the Chappe brothers set about devising a system of communication that would allow the central government to receive intelligence and to transmit orders in the shortest possible time. On 2 March 1791, at 11 am, they sent the message "si vous réussissez, vous serez bientôt couverts de gloire" (If you succeed, you will soon bask in glory) between Brulon and Parce, a distance of 16 kilometres (9.9 mi). The first means used a combination of black and white panels, clocks, telescopes, and codebooks to send their message.
In 1792, Claude was appointed Ingénieur-Télégraphiste and charged with establishing a line of stations between Paris and Lille, a distance of 230 kilometres (about 143 miles). It was used to carry dispatches for the war between France and Austria. In 1794, it brought news of a French capture of Condé-sur-l'Escaut from the Austrians less than an hour after it occurred.
The Prussian system was put into effect in the 1830s. However, they were highly dependent on good weather and daylight to work and even then could accommodate only about two words per minute. The last commercial semaphore link ceased operation in Sweden in 1880. As of 1895, France still operated coastal commercial semaphore telegraph stations, for ship-to-shore communication.
The early ideas for an electric telegraph included using electrostatic deflections of pith balls (1753), and electrochemical bubbles in acid (Campillo (1804); von Sömmering, 1809). The first experimental system over a substantial distance was electrostatic (Ronalds, 1816). Ronalds offered his invention to the British Admiralty, but it was rejected as unnecessary. In the end, electrostatic telegraphs were abandoned in favour of electromechanical designs using electromagnets (electromagnetic systems). An early experimental electromagnetic system (Schilling, 1832) led to a proposal to establish a telegraph between St Petersburg and Kronstadt, but it was never completed.
The first electric telegraph in regular use (Gauss and Weber, 1833) connected Göttingen Observatory to the Institute of Physics about 1 km away. The first commercial telegraph (Cooke and Wheatstone, 1837) was initially provided for signalling on a section of the Great Western Railway in 1838.
Most of these early systems required multiple wires (Ronalds' system was an exception), but the system developed in the United States (Morse and Vail, 1837) was a single-wire system. This was the system that first used the soon-to-become-ubiquitous Morse code. By 1844, the Morse system connected Baltimore to Washington, and by 1861 the west coast of the continent was connected to the east coast. The Cooke and Wheatstone telegraph, in a series of improvements, also ended up with a one-wire system, but still using their own code and needle displays.
At first associated with the railways, the electric telegraph quickly became a means of more general communication. The Morse telegraph was officially adopted as the standard for continental European telegraphy in 1851 with a revised code, which later became the basis of International Morse Code. However, Great Britain and the British Empire continued to use the Cooke and Wheatstone system, in some places as late as the 1930s. Likewise, the United States continued to use American Morse code internally, requiring translation operators skilled in both codes for international messages.
Telegraphy was driven by the need to reduce sending costs, either in hand-work per message or by increasing the sending rate. While many experimental systems employing moving pointers and various electrical encodings proved too complicated and unreliable, a successful advance in the sending rate was achieved through the development of telegraphese.
The first system that didn't require skilled technicians to operate was Sir Charles Wheatstone's ABC system in 1840 where the letters of the alphabet were arranged around a clock-face, and the signal caused a needle to indicate the letter. This early system required the receiver to be present in real time to record the message and it reached speeds of up to 15 words a minute.
In 1846, Alexander Bain patented a chemical telegraph in Edinburgh. The signal current made a readable mark on a moving paper tape soaked in a mixture of ammonium nitrate and potassium ferrocyanide, which gave a blue mark when a current was passed through it.
David Edward Hughes invented the printing telegraph in 1855; it used a keyboard of 26 keys for the alphabet and a spinning type wheel that determined the letter being transmitted by the length of time that had elapsed since the previous transmission. The system allowed for automatic recording on the receiving end. The system was very stable and accurate and became the accepted around the world.
The next improvement was the Baudot code of 1874. French engineer Émile Baudot patented a printing telegraph in which the signals were translated automatically into typographic characters. Each character was assigned a unique code based on the sequence of just five contacts. Operators had to maintain a steady rhythm, and the usual speed of operation was 30 words per minute.
By this point, reception had been automated, but the speed and accuracy of the transmission were still limited to the skill of the human operator. The first practical automated system was patented by Charles Wheatstone, the original inventor of the telegraph. The message (in Morse code) was typed onto a piece of perforated tape using a keyboard-like device called the 'Stick Punch'. The transmitter automatically ran the tape through and transmitted the message at the then exceptionally high speed of 70 words per minute.
Teleprinters were invented in order to send and receive messages without the need for operators trained in the use of Morse code. A system of two teleprinters, with one operator trained to use a typewriter, replaced two trained Morse code operators. The teleprinter system improved message speed and delivery time, making it possible for messages to be flashed across a country with little manual intervention.
Early teleprinters used the ITA-1 Baudot code, a five-bit code. This yielded only thirty-two codes, so it was over-defined into two "shifts", "letters", and "figures". An explicit, unshared shift code prefaced each set of letters and figures. In 1901, Baudot's code was modified by Donald Murray and around 1930, the CCITT introduced the International Telegraph Alphabet No. 2 (ITA2) code as an international standard.
By 1935, message routing was the last great barrier to full automation. Large telegraphy providers began to develop systems that used telephone-like rotary dialling to connect teletypewriters. These machines were called "Telex" (TELegraph EXchange). Telex machines first performed rotary-telephone-style pulse dialling for circuit switching and then sent data by Baudot code. This "type A" Telex routing functionally automated message routing.
Telex began in Germany as a research and development program in 1926 that became an operational teleprinter service in 1933. The service was operated by the Reichspost (Reich postal service) and had a speed of 50 baud – approximately 66 words-per-minute.
At the rate of 45.45 (±0.5%) baud—considered speedy at the time—up to 25 telex channels could share a single long-distance telephone channel by using voice frequency telegraphy multiplexing, making telex the least expensive method of reliable long-distance communication.
Automatic teleprinter exchange service was introduced into Canada by CPR Telegraphs and CN Telegraph in July 1957, and in 1958, Western Union started to build a Telex network in the United States.
Beginning in 1956, telegrams begun to be transmitted over the Telex network using the ITU F.20 standard named Gentex in order to lower the costs for some European telecommunications companies by allowing the sending telegraph station to connect directly to the receiving station.
Oceanic telegraph cablesEdit
Soon after the first successful telegraph systems were operational, the possibility of transmitting messages across the sea by way of submarine communications cables was first mooted. One of the primary technical challenges was to insulate the submarine cable sufficiently to prevent the current from leaking out into the water. In 1842, a Scottish surgeon William Montgomerie introduced Gutta-percha, the adhesive juice of the Palaquium gutta tree, to Europe. Michael Faraday and Wheatstone soon discovered the merits of gutta-percha as an insulator, and in 1845, the latter suggested that it should be employed to cover the wire which was proposed to be laid from Dover to Calais. It was tried on a wire laid across the Rhine between Deutz and Cologne. In 1849, C.V. Walker, electrician to the South Eastern Railway, submerged a two-mile wire coated with gutta-percha off the coast from Folkestone, which was tested successfully.
John Watkins Brett, an engineer from Bristol, sought and obtained permission from Louis-Philippe in 1847 to establish telegraphic communication between France and England. The first undersea cable was laid in 1850 and connected London with Paris. After an initial exchange of greetings between Queen Victoria and President Napoleon, it was almost immediately severed by a French fishing vessel. The line was relaid the next year and then followed by connections to Ireland and the Low Countries.
The Atlantic Telegraph Company was formed in London in 1856 to undertake to construct a commercial telegraph cable across the Atlantic Ocean. It was successfully completed on 27 July 1866, by the ship SS Great Eastern, captained by Sir James Anderson after many mishaps along the way. Earlier transatlantic submarine cables installations were attempted in 1857, 1858, and 1865. The 1858 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. An overland telegraph from Britain to India was first connected in 1866 but was unreliable so a submarine telegraph cable was connected in 1870. Several telegraph companies were 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. The telegraph across the Pacific was completed in 1902, finally encircling the world.
From the 1850s until well into the 20th century, British submarine cable systems dominated the world system. This was set out as a formal strategic goal, which became known as the All Red Line. In 1896, there were thirty cable laying ships in the world and twenty-four of them were owned by British companies. In 1892, British companies owned and operated two-thirds of the world's cables and by 1923, their share was still 42.7 percent. During World War I, Britain's telegraph communications were almost completely uninterrupted while it was able to quickly cut Germany's cables worldwide.
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. Frederick Bakewell made several improvements on Bain's design and demonstrated a telefax machine. 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.
In 1881, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, not requiring manual plotting or drawing. Around 1900, German physicist Arthur Korn invented the Bildtelegraph widespread in continental Europe especially since a widely noticed transmission of a wanted-person photograph from Paris to London in 1908 used until the wider distribution of the radiofax. Its main competitors were the Bélinographe by Édouard Belin first, then since the 1930s, the Hellschreiber, invented in 1929 by German inventor Rudolf Hell, a pioneer in mechanical image scanning and transmission.
The late 1880s through to the 1890s saw the discovery and then development of a newly understood phenomenon into a form of wireless telegraphy, called Hertzian wave wireless telegraphy, radiotelegraphy, or (later) simply "radio". Between 1886 and 1888, Heinrich Rudolf Hertz published the results of his experiments where he was able to transmit electromagnetic waves (radio waves) through the air, proving James Clerk Maxwell's 1873 theory of electromagnetic radiation. Many scientists and inventors experimented with this new phenomenon but the general consensus was that these new waves (similar to light) would be just as short range as light, and, therefore, useless for long range communication.
At the end of 1894, the young Italian inventor Guglielmo Marconi began working on the idea of building a commercial wireless telegraphy system based on the use of Hertzian waves (radio waves), a line of inquiry that he noted other inventors did not seem to be pursuing. Building on the ideas of previous scientists and inventors Marconi re-engineered their apparatus by trial and error attempting to build a radio-based wireless telegraphic system that would function the same as wired telegraphy. He would work on the system through 1895 in his lab and then in field tests making improvements to extend its range. After many breakthroughs, including applying the wired telegraphy concept of grounding the transmitter and receiver, Marconi was able, by early 1896, to transmit radio far beyond the short ranges that had been predicted. Having failed to interest the Italian government, the 22-year-old inventor brought his telegraphy system to Britain in 1896 and met William Preece, a Welshman, who was a major figure in the field and Chief Engineer of the General Post Office. A series of demonstrations for the British government followed—by March 1897, Marconi had transmitted Morse code signals over a distance of about 6 kilometres (3.7 mi) across Salisbury Plain.
On 13 May 1897, Marconi, assisted by George Kemp, a Cardiff Post Office engineer, transmitted the first wireless signals over water to Lavernock (near Penarth in Wales) from Flat Holm. The message sent was "ARE YOU READY". From his Fraserburgh base, he transmitted the first long-distance, cross-country wireless signal to Poldhu in Cornwall.[when?] His star rising, he was soon sending signals across The English channel (1899), from shore to ship (1899) and finally across the Atlantic (1901). A study of these demonstrations of radio, with scientists trying to work out how a phenomenon predicted to have a short range could transmit "over the horizon", led to the discovery of a radio reflecting layer in the Earth's atmosphere in 1902, later called the ionosphere.
Radiotelegraphy proved effective for rescue work in sea disasters by enabling effective communication between ships and from ship to shore. In 1904, Marconi began the first commercial service to transmit nightly news summaries to subscribing ships, which could incorporate them into their on-board newspapers. A regular transatlantic radio-telegraph service was finally begun on 17 October 1907. Notably, Marconi's apparatus was used to help rescue efforts after the sinking of Titanic. Britain's postmaster-general summed up, referring to the Titanic disaster, "Those who have been saved, have been saved through one man, Mr. Marconi...and his marvellous invention."
Around 1965, DARPA commissioned a study of decentralised switching systems. Some of the ideas developed in this study provided inspiration for the development of the ARPANET packet switching research network, which later grew to become the public Internet.
As the PSTN became a digital network, T-carrier "synchronous" networks became commonplace in the U.S. A T1 line has a "frame" of 193 bits that repeats 8000 times per second. The first bit called the "sync" bit alternates between 1 and 0 to identify the start of the frames. The rest of the frame provides 8 bits for each of 24 separate voice or data channels. Customarily, a T-1 link is sent over a balanced twisted pair, isolated with transformers to prevent current flow. Europeans adopted a similar system (E-1) of 32 channels (with one channel for frame synchronisation).
Later, SONET and SDH were adapted to combine carrier channels into groups that could be sent over optic fiber. The capacity of an optic fibre is often extended with wavelength division multiplexing, rather than rerigging new fibre. Rigging several fibres in the same structures as the first fibre is usually easy and inexpensive, and many fibre installations include unused spare "dark fibre", "dark wavelengths", and unused parts of the SONET frame, so-called "virtual channels".
In 2002, the Internet was used by Kevin Warwick at the University of Reading to communicate neural signals, in purely electronic form, telegraphically between the nervous systems of two humans, potentially opening up a new form of communication combining the Internet and telegraphy.
Since the Internet operates over any digital transmission medium, further evolution of telegraphic technology will be effectively concealed from users.
E-mail was first invented for CTSS and similar time sharing systems of the era in the mid-1960s. At first, e-mail was possible only between different accounts on the same computer (typically a mainframe). ARPANET allowed different computers to be connected to allow e-mails to be relayed from computer to computer, with the first ARPANET e-mail being sent in 1971. Multics also pioneered instant messaging between computer users in the mid-1970s. With the growth of the Internet, e-mail began to be possible between any two computers with access to the Internet.
Various private networks like UUNET (founded 1987), the Well (1985), and GEnie (1985) had e-mail from the 1970s, but subscriptions were quite expensive for an individual, US$25 to US$50 per month, just for e-mail. Internet use was then largely limited to government, academia, and other government contractors until the net was opened to commercial use in the 1980s.
By the early 1990s, modems made e-mail a viable alternative to Telex systems in a business environment. But individual e-mail accounts were not widely available until local Internet service providers were in place, although demand grew rapidly, as e-mail was seen as the Internet's killer app. It allowed anyone to email anyone, whereas previously, different system had been walled off from each other, such that America Online subscribers could email only other America Online subscribers, Compuserve subscribers could email only other Compuserve subscribers, etc. The broad user base created by the demand for e-mail smoothed the way for the rapid acceptance of the World Wide Web in the mid-1990s. Fax machines were another technology that helped displace the telegram.
On Monday, 12 July 1999, a final telegram was sent from the National Liberty Ship Memorial, the SS Jeremiah O'Brien, in San Francisco Bay to President Bill Clinton in the White House. Officials of Globe Wireless reported that "The message was 95 words, and it took six or eight minutes to copy it." They then transmitted the message to the White House via e-mail. That event was also used to mark the final commercial U.S. ship-to-shore telegraph message transmitted from North America by Globe Wireless, a company founded in 1911. Sent from its wireless station at Half Moon Bay, California, the sign-off message was a repeat of Samuel F. B. Morse's message 155 years earlier, "What hath God wrought?"
A telegram service is the delivery of written messages that have been sent by telegraph to a local telegraph office. These messages are delivered by hand to the addressee.
The average length of a telegram in the 1900s in the US was 11.93 words; more than half of the messages were 10 words or fewer.
According to another study, the mean length of the telegrams sent in the UK before 1950 was 14.6 words or 78.8 characters.
Prior to the electrical telegraph, ancient civilizations, such as Greece, Egypt, and China, transmitted long-distance information using drumbeats, flame beacons, or light flashes with a heliograph. Later, nearly all information was limited to traveling at the speed of a human or animal. The telegraph freed communication from the time constraints of postal mail and revolutionized the global economy and society. By the end of the 19th century, the telegraph was becoming an increasingly common medium of communication for ordinary people. The telegraph isolated the message (information) from the physical movement of objects or the process.
Telegraphy facilitated the growth of organizations "in the railroads, consolidated financial and commodity markets, and reduced information costs within and between firms". This immense growth in the business sectors influenced society to embrace the use of telegrams.
Worldwide telegraphy changed the gathering of information for news reporting. Messages and information would now travel far and wide, and the telegraph demanded a language "stripped of the local, the regional; and colloquial", to better facilitate a worldwide media language. Media language had to be standardized, which led to the gradual disappearance of different forms of speech and styles of journalism and storytelling.
Numerous newspapers and news outlets in various countries, such as The Daily Telegraph in Britain, The Telegraph in India, De Telegraaf in the Netherlands, and the Jewish Telegraphic Agency in the US, were given names which include the word "telegraph" due to their having received news by means of electric telegraphy. Some of these names are retained even though more sophisticated means are now used. A newspaper in Indian state of Tamil Nadu is named as Dhina Thanthi which means daily telegraph.
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|Wikisource has original text related to this article:|
|Wikimedia Commons has media related to Telegraphy.|
- "Telegraph". Encyclopædia Britannica (11th ed.). 1911.
- The Porthcurno Telegraph Museum The biggest Telegraph station in the world, now a museum
- Distant Writing—The History of the Telegraph Companies in Britain between 1838 and 1868
- Western Union Telegraph Company Records, 1820–1995 Archives Center, National Museum of American History, Smithsonian Institution.
- Early telegraphy and fax engineering, still operable in a German computer museum
- "Telegram Falls Silent Stop Era Ends Stop", The New York Times, February 6, 2006
- International Facilities of the American Carriers – an overview of the U.S. international cable network in 1950