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Electrical telegraphs were point-to-point text messaging systems, primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called telegraphs, that were devised to communicate text messages quicker than physical transportation. Electrical telegraphy can be considered to be the first example of electrical engineering.
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs.
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
Timeline of electromagnetism and classical optics lists, within the history of electromagnetism, the associated theories, technology, and events.
Sir Charles Wheatstone FRS FRSE, was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope, and the Playfair cipher. However, Wheatstone is best known for his contributions in the development of the Wheatstone bridge, originally invented by Samuel Hunter Christie, which is used to measure an unknown electrical resistance, and as a major figure in the development of telegraphy.
Peter Barlow was an English mathematician and physicist.
A telegraph code is one of the character encodings used to transmit information by telegraphy. Morse code is the best-known such code. Telegraphy usually refers to the electrical telegraph, but telegraph systems using the optical telegraph were in use before that. A code consists of a number of code points, each corresponding to a letter of the alphabet, a numeral, or some other character. In codes intended for machines rather than humans, code points for control characters, such as carriage return, are required to control the operation of the mechanism. Each code point is made up of a number of elements arranged in a unique way for that character. There are usually two types of element, but more element types were employed in some codes not intended for machines. For instance, American Morse code had about five elements, rather than the two of International Morse Code.
Edward Davy was an English physician, scientist, and inventor who played a prominent role in the development of telegraphy, and invented an electric relay.
Baron Pavel Lvovitch Schilling (1786–1837), also known as Paul Schilling, was a Russian military officer and diplomat of Baltic German origin. The majority of his career was spent working for the imperial Russian Ministry of Foreign Affairs as a language officer at the Russian embassy in Munich. As a military officer, he took part in the War of the Sixth Coalition against Napoleon. In his later career, he was transferred to the Asian department of the ministry and undertook a tour of Mongolia to collect ancient manuscripts.
Cromwell Fleetwood Varley, FRSA was an English engineer, particularly associated with the development of the electric telegraph and the transatlantic telegraph cable. He also took interest in the claims of parapsychology and spiritualism.
The invention of radio communication was preceded by many decades of establishing theoretical underpinnings, discovery and experimental investigation of radio waves, and engineering and technical developments related to their transmission and detection. These developments allowed Guglielmo Marconi to turn radio waves into a wireless communication system.
The Signal Corps in the American Civil War comprised two organizations: the U.S. Army Signal Corps, which began with the appointment of Major Albert J. Myer as its first signal officer just before the war and remains an entity to this day, and the Confederate States Army Signal Corps, a much smaller group of officers and men, using similar organizations and techniques as their Union opponents. Both accomplished tactical and strategic communications for the warring armies, including electromagnetic telegraphy and aerial telegraphy. Although both services had an implicit mission of battlefield observation, intelligence gathering, and artillery fire direction from their elevated signal stations, the Confederate Signal Corps also included an explicit espionage function.
The pasilalinic-sympathetic compass, also referred to as the snail telegraph, was a contraption built to test the pseudo-scientific hypothesis that snails create a permanent telepathic link when they mate. The device was developed by French occultist Jacques-Toussaint Benoît with the supposed assistance of an American colleague monsieur Biat-Chrétien in the 1850s.
The Cooke and Wheatstone telegraph was an early electrical telegraph system dating from the 1830s invented by English inventor William Fothergill Cooke and English scientist Charles Wheatstone. It was a form of needle telegraph, and the first telegraph system to be put into commercial service. The receiver consisted of a number of needles which could be moved by electromagnetic coils to point to letters on a board. This feature was liked by early users who were unwilling to learn codes, and employers who did not want to invest in staff training.
A needle telegraph is an electrical telegraph that uses indicating needles moved electromagnetically as its means of displaying messages. It is one of the two main types of electromagnetic telegraph, the other being the armature system, as exemplified by the telegraph of Samuel Morse in the United States. Needle telegraphs were widely used in Europe and the British Empire during the nineteenth century.
The British and Irish Magnetic Telegraph Company was founded by John Brett in 1850. The Magnetic was the principal competitor to the largest telegraph company in the United Kingdom, the Electric Telegraph Company. The Magnetic was the leading company in Ireland, while the Electric was the leading company in mainland Britain. Between them, they dominated the market until the telegraph was nationalised in 1870.
In the nineteenth century, the United Kingdom of Great Britain and Ireland had the world's first commercial telegraph company. British telegraphy dominated international telecommunications well into the twentieth. Telegraphy is the sending of textual messages by human operators using symbolic codes. Electrical telegraphy used conducting wires to send messages, often incorporating a telegram service to deliver the telegraphed communication from the telegraph office. This is distinct from optical telegraphy that preceded it and the radiotelegraphy that followed. Though Francis Ronalds first demonstrated a working telegraph over a substantial distance in 1816, he was unable to put it into practical use. Starting in 1836, William Fothergill Cooke, with the scientific assistance of Charles Wheatstone, developed the Cooke and Wheatstone telegraph. The needle telegraph instrument suggested by Wheatstone, the battery invented by John Frederic Daniell, and the relay invented by Edward Davy were important components of this system.
Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a corresponding saving on the labour required to string it. The benefits of doing this were not immediately noticed by telegraph pioneers, but it rapidly became the norm after the first earth-return telegraph was put into service by Carl August von Steinheil in 1838.
The Schilling telegraph is a needle telegraph invented by Pavel Schilling in the nineteenth century. It consists of a bank of needle instruments which between them display a binary code representing a letter or numeral. Signals were sent from a piano-like keyboard, and an additional circuit was provided for calling attention at the receiving end by setting off an alarm.
References
- ↑ Charles MacKay, Extraordinary Popular Delusions and the Madness of Crowds
- ↑ Jastrow, Joseph (1900). Fact and Fable in Psychology. Boston, Houghton, Mifflin and Co. p. 262.
- ↑ Fahie, John Joseph (1884). A History of Electric Telegraphy, to the Year 1837. E. & F. N. Spon. p. 19 . Retrieved 27 May 2017.
- ↑ Standage, Tom (1998). The Victorian Internet: the remarkable story of the telegraph and the nineteenth century's on-line pioneers. New York : Walker and Co. p. 4–5, 34–35. ISBN 0-425-17169-8.
- ↑ "Le nez d'un notaire". August 19, 1972 – via IMDb.
- ↑ Fahie, John Joseph (1883). "A history of the electric telegraphy, to the year 1837". The Electrical Journal. XI: 65.
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