telegraph
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What is a telegraph?
A telegraph is any system that transmits information by coded signals across a distance. While telegraphic systems have existed for centuries, the term commonly refers to the electric telegraph, which emerged in the mid-19th century. For over a century, it served as the primary method for transmitting printed information via wire or radio wave. The word telegraph comes from the Greek words tele (distant) and graphein (to write).
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How does a telegraph send messages?
The electric telegraph sends messages over a distance using coded signals. The first practical systems emerged in Britain and the United States in 1837. In the system developed by William Fothergill Cooke and Charles Wheatstone in Britain, needles pointed to letters or numbers when electric current passed through the wires.
Samuel Morse devised a system of dots and dashes to represent letters and numbers and was granted a patent in 1837. Morse's system used a device to make and break contact between the battery and the wire to the receiver, which embossed the dots and dashes on paper. Alfred Vail refined the Morse code and improved the system's mechanical design. The Morse code was later modified to accommodate diacritics for non-English text and became the International Morse Code.
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What is Morse code and how is it used with the telegraph?
Morse code is a system that uses dots, dashes, and spaces to represent letters, numerals, and punctuation, for transmitting messages via electrical pulses or other signals. Samuel F.B. Morse invented it in the 1830s for electrical telegraphy. His assistant, Alfred Lewis Vail, improved it. Morse code uses varied arrangements of short and long signals to send information.
The electric telegraph is a device that sends coded signals over a distance. Morse's telegraph transmitter used a portarule with dots and dashes that made contact between a battery and a wire to send signals. The receiver embossed the dots and dashes on paper. The first public demonstration of the telegraph occurred in 1844.
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When and why was the telegraph invented?
The electric telegraph emerged from 18th-century electrical science, with Alessandro Volta's battery (1800) enabling effective electric power. In 1837, William Fothergill Cooke and Charles Wheatstone patented a telegraph using six wires to move needles to point at letters.
Separately, Samuel F.B. Morse devised dots and dashes for letters, patenting it in 1837. With Alfred Vail's help, the system was improved with a simple key and refined code. The first public demonstration occurred in 1844, inaugurating the telegraph era in the United States.
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How did the telegraph change communication compared to older methods?
The telegraph revolutionized communication by enabling reliable, instantaneous communication over vast distances, unlike previous methods. Visual telegraph systems using towers with movable arms and messengers on horseback had been the standard.
The electric telegraph, developed in Britain by William Fothergill Cooke and Charles Wheatstone and in the U.S. by Samuel F.B. Morse, made near-real-time communication possible. Morse also created Morse code, a universal code of dots, dashes, and spaces, for use in any telegraphy system. By 1861, the first transcontinental telegraph line connected San Francisco to the East Coast.
This technology quickly impacted diplomacy, commerce, military operations, journalism, and everyday life. The telegraph aided railroad traffic control and helped maintain law and order in the American West. The Associated Press and other wire services used it to transmit national and international news.
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What were some important events or industries that used the telegraph?
The telegraph revolutionized communication, impacting various industries and events.
- News: The telegraph became a vital tool for transmitting news, leading to the formation of the Associated Press to pool telegraph expenses.
- Railroads: The telegraph aided railroad traffic control by allowing communication between fixed signal points, improving safety and efficiency.
- Military: The British army first used the telegraph in the Crimean War in 1854. It played a deciding factor in the Indian Mutiny. During the American Civil War, the electric telegraph was widely used, with mobile field service provided by wagon trains equipped with insulated wire for rapid deployment.
- Transcontinental Communication: In 1861, the first transcontinental telegraph line connected San Francisco to the Midwest and the East Coast.
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telegraph, any device or system that allows the transmission of information by coded signal over distance. Many telegraphic systems have been used over the centuries, but the term is most often understood to refer to the electric telegraph, which was developed in the mid-19th century and for more than 100 years was the principal means of transmitting printed information by wire or radio wave.
Preelectric telegraph systems
The word telegraph is derived from the Greek words tele, meaning “distant,” and graphein, meaning “to write.” It came into use toward the end of the 18th century to describe an optical semaphore system developed in France. However, many types of telegraphic communication have been employed since before recorded history. The earliest methods of communication at a distance made use of such media as smoke, fire, drums, and reflected rays of the Sun. Visual signals given by flags and torches were used for short-range communication and continued to be utilized well into the 20th century, when the two-flag semaphore system was widely used, particularly by the world’s navies.
Before the development of the electric telegraph, visual systems were used to convey messages over distances by means of variable displays. One of the most successful of the visual telegraphs was the semaphore developed in France by the Chappe brothers, Claude and Ignace, in 1791. This system consisted of pairs of movable arms mounted at the ends of a crossbeam on hilltop towers. Each arm of the semaphore could assume seven angular positions 45° apart, and the horizontal beam could tilt 45° clockwise or counterclockwise. In this manner it was possible to represent numbers and the letters of the alphabet. Chains of these towers were built to permit transmission over long distances. The towers were spaced at intervals of 5 to 10 km (3 to 6 miles), and a signaling rate of three symbols per minute could be achieved.
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Another widely used visual telegraph was developed in 1795 by George Murray in England. In Murray’s device, characters were sent by opening and closing various combinations of six shutters. This system rapidly caught on in England and in the United States, where a number of sites bearing the name Telegraph Hill or Signal Hill can still be found, particularly in coastal regions. Visual telegraphs were completely replaced by the electric telegraph by the middle of the 19th century.
The beginning of electric telegraphy
The first transmitters and receivers
The electric telegraph did not burst suddenly upon the scene but rather resulted from a scientific evolution that had been taking place since the 18th century in the field of electricity. One of the key developments was the invention of the voltaic cell in 1800 by Alessandro Volta of Italy. This made it possible to power electric devices in a more effective manner using relatively low voltages and high currents. Previous methods of producing electricity employed frictional generation of static electricity, which led to high voltages and low currents. Many devices incorporating high-voltage static electricity and various detectors such as pith balls and sparks were proposed for use in telegraphic systems. All were unsuccessful, however, because the severe losses in the transmission wires, particularly in bad weather, limited reliable operation to relatively short distances. Application of the battery to telegraphy was made possible by several further developments in the new science of electromagnetism. In 1820 Hans Christian Ørsted of Denmark discovered that a magnetic needle could be deflected by a wire carrying an electric current. In 1825 in Britain William Sturgeon discovered the multiturn electromagnet, and in 1831 Michael Faraday of Britain and Joseph Henry of the United States refined the science of electromagnetism sufficiently to make it possible to design practical electromagnetic devices.
The first two practical electric telegraphs appeared at almost the same time. In 1837 the British inventors Sir William Fothergill Cooke and Sir Charles Wheatstone obtained a patent on a telegraph system that employed six wires and actuated five needle pointers attached to five galvanoscopes at the receiver. If currents were sent through the proper wires, the needles could be made to point to specific letters and numbers on their mounting plate.
In 1832 Samuel F.B. Morse, a professor of painting and sculpture at the University of the City of New York (later New York University), became interested in the possibility of electric telegraphy and made sketches of ideas for such a system. In 1835 he devised a system of dots and dashes to represent letters and numbers. In 1837 he was granted a patent on an electromagnetic telegraph. Morse’s original transmitter incorporated a device called a portarule, which employed molded type with built-in dots and dashes. The type could be moved through a mechanism in such a manner that the dots and dashes would make and break the contact between the battery and the wire to the receiver. The receiver, or register, embossed the dots and dashes on an unwinding strip of paper that passed under a stylus. The stylus was actuated by an electromagnet turned on and off by the signals from the transmitter.
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Morse had formed a partnership with Alfred Vail, who was a clever mechanic and is credited with many contributions to the Morse system. Among them are the replacement of the portarule transmitter by a simple make-and-break key, the refinement of the Morse Code so that the shortest code sequences were assigned to the most frequently occurring letters, and the improvement of the mechanical design of all the system components. The first demonstration of the system by Morse was conducted for his friends at his workplace in 1837. In 1843 Morse obtained financial support from the U.S. government to build a demonstration telegraph system 60 km (35 miles) long between Washington, D.C., and Baltimore, Md. Wires were attached by glass insulators to poles alongside a railroad. The system was completed and public use initiated on May 24, 1844, with transmission of the message, “What hath God wrought!” This inaugurated the telegraph era in the United States, which was to last more than 100 years.