Electrical telegraph
From Wikipedia, the free encyclopedia
The electrical telegraph is a telegraph that uses electric signals. The electromagnetic telegraph is a device for transmission of written messages without physical transport of letters over wire. The first telegraphs were built independently in the apartment of Russian inventor Pavel Shilling in St.Petersburg, in 1832 where it was demonstrated to wide public. Another electromagnetic telegraph was used publicly by Carl Friedrich Gauss and Wilhelm Weber in Göttingen's university in 1833.
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[edit] History
[edit] Early works and messages
In 1795 Francisco de Salva offered an electrostatical telegraph. Telegraphy based on static electricity was impractical because of the high voltages required. Alessandro Volta invented the Voltaic Pile in 1800, allowing a continuous current for experimentation. Samuel T. Soemmering constructed his electrochemical telegraph in 1809. Hans Christian Ørsted discovered in 1820 that an electric current produces a magnetic field which will deflect a compass needle. Also in 1820, Johann Schweigger invented the galvanometer, with a coil of wire around a compass, which could be used as a sensitive indicator for electric current. In 1821, André-Marie Ampère suggested that telegraphy could be done by a system of galvanometers, with one wire per galvanometer to indicate each letter, and said he had experimented successfully with such a system. In 1824, Peter Barlow said that such a system only worked to a distance of about 200 feet, and so was impractical. William Sturgeon in 1825 invented the electromagnet, with a single winding of uninsulated wire on a piece of varnished iron, which increased the magnetic force produced by electric current. In 1828, Joseph Henry improved the electromagnet by placing on it several windings of insulated wire, creating a much more powerful electromagnet which could operate a telegraph through the high resistance of long telegraph wires. An electromagnetic telegraph was created by Baron Schilling in 1832. Carl Friedrich Gauß and Wilhelm Weber built an electromagnetic telegraph in 1833 in Göttingen. In 1835 Joseph Henry invented the relay, by which a weak current over long wires could operate a powerful local electromagnet. <ref>Joseph Henry: Inventor of the Telegraph? Smithsonian Institution. Retrieved on 2006-06-29.</ref> <ref>Thomas Coulson (1950). Joseph Henry: His Life and Work. Princeton: Princeton University Press.</ref>
The first commercial electrical telegraph was constructed by Sir William Fothergill Cooke and entered use on the Great Western Railway. Cooke and Wheatstone patented it in May 1837 as an alarm system. It ran for 13 miles from Paddington station to West Drayton and came into operation on April 9, 1839. In early 1845, John Tawell was apprehended following the use of a needle telegraph message from Slough to Paddington on January 1 1845. This is thought to be the first use of the telegraph to catch a murderer. The message was:
- A murder has just been committed at Salt Hill and the suspected murderer was seen to take a first class ticket to London by the train that left Slough at 7.42pm. He is in the garb of a Kwaker with a brown great coat on which reaches his feet. He is in the last compartment of the second first-class carriage
The reason for the misspelling of 'Quaker' was that the British system did not support the letter Q.
An electrical telegraph was independently developed in the United States by Dr. David Alter in 1836, and developed and patented in the United States in 1837 by Samuel Morse.
[edit] Transatlantic era
On October 24, 1861, the first transcontinental telegraph system was established. Spanning North America, an existing network in the eastern United States was connected to the small network in California by a link between Omaha and Carson City via Salt Lake City. The slower Pony Express system ceased operation a month later.
The first successful transatlantic telegraph cable was completed on July 27, 1866, allowing transatlantic telegraph communications for the first time. Earlier submarine cable transatlantic cables installed in 1857 and 1858 only operated for a few days or weeks before they failed. The study of underwater telegraph cables accelerated interest in mathematical analysis of these transmission lines.
In 1867, David Brooks (while working for the Central Pacific Railroad) was awarded U.S. Patent 63,206 (March 26) and U.S. Patent 69,622 (October 9) for his improvements to telegraph insulators. He was also awarded reissue number 2,717 on August 6, 1867, for U.S. Patent 45,221, which was originally awarded to him on November 29, 1864, for his insulator design. Brooks' patents allowed the Central Pacific to more easily communicate with construction crews building the First Transcontinental Railroad in America; the completion of the railroad was broadcast by telegraph on May 10, 1869, with the telegrapher striking his key in unison with the strikes on the Golden Spike during the completion ceremony.
Another advancement in telegraph technology occurred on August 9, 1892, when Thomas Edison received a patent for a two-way telegraph (U.S. Patent 0480,567, "Duplex Telegraph") . On January 27, 2006, Western Union discontinued all telegram and commercial messaging services, though it still offered its money transfer services.
[edit] Global communication
Within 29 years of its first installation at Euston Station, the telegraph network crossed the oceans to every continent, making instant global communication possible for the first time. Its development allowed newspapers to cover significant world events in near real-time, revolutionized business, particularly trading businesses, and allowed huge fortunes to be won and lost in a flurry of investment in research and infrastructure building reminiscent of the 1990s dot-com bubble.
[edit] Gauß-Weber telegraph and Carl Steinheil
Carl Friedrich Gauß, one of the most influential mathematicians of the early 19th century, developed a new theory on the Earth's magnetism in 1831, together with the physics professor Wilhelm Weber in Göttingen. Among the most important were the unifilar- and bifilar- magnetometer, making them able to measure even the smallest deflexions of the needle. They installed a 1000 m long wire above the town's roofs, which was allowed them on 6 May 1833. Gauß combined the Poggendorff-Schweigger multiplikator with his magnetometer to build a more sensible device, the galvanometer. To change the way of the electric flow, he constructed a commutator on his own. As a result, one was able to make the needle in the distance move in the direction of the commutator on the other end of the line. At first, they used the telegraph to coordinate time, but soon they developed other signals, finally their own alphabet. It was not binary, but then based on four amplitudes of the needle. He was convinced, that this communication would be a help to his kingdom's towns. Later the same year, he used instead of a Volta pole an induction pulse, being able to transmit 7 letters a minute instead of 2. The inventors and university were too poor to develop the telegraph on their own, but received funding by Alexander von Humboldt. Carl August Steinheil in München was able to build a telegraph network within Munich in 1835-6, and installed a telegraph line along the first German railroad in 1835. He discovered that the ground conducts electricity, so that costs were reduced by half. King Ludwig I. of Bavaria was amazed: "You are lucky to live in our days. 200 years ago, you would have been burned for performing witchcraft."
[edit] Schilling telegraph
The telegraph invented by Baron Schilling von Canstedt in 1832 had a transmitting device which consisted of a keyboard with 16 black-and-white keys. These served for closing the electric current. Receiving instrument consisted of 6 galvanometers with the magnetic needles, suspended from the silk threads to the copper counters. Both stations of Shilling's telegraph were connected by eight wires and six from them were connected with the galvanometers, one served for the return current and one - for the draftable apparatus (electric bell). When at the starting station the operator pressed key and released electric current, the corresponding pointer was slanted at the receiving station. Different positions of black and white flags on different disks gave the conditional combinations, which corresponded to the letters of alphabet or to numbers. Later Pavel Shilling improved its apparatus. He reduced amount of connecting cables from 8 to 2 wires only.
On October 21, 1832, Schilling managed a short-distance transmission of signals by positioning two telegraphs in two different rooms of his apartment. In 1836 the Schilling's telegraph underwent successful tests on experimental underground - underwater cable line, with the extent about 5 kilometers, laid around the building of the main Admiralty in Saint Petersburg, and was approved for the relation between Peterhof and Kronshtadt. Schilling also was one of the first to put into practice the idea of the binary system of signal transmission. William Fothergill Cooke studied in Heidelberg in 1834-6 anatomy, where the physics professor introduced them to the Schilling von Canstedt's telegraph in 1836. He perfected a system and patented it with Charles Wheatstone in 1837. Cooke installed the system in short lengths on a number of railways over the next few years including the London & Birmingham, the Great Western, London & Blackwall, London & South Western, and London & South Eastern. In 1845 a consortium of business men purchased the patents from Cooke.
[edit] Alter and the Elderton Telegraph
Across the Atlantic 1836, a American scientist, Dr. David Alter, invented the first known American electric telegraph in Elderton, Pennsylvania, one year before the much more popular Morse telegraph was invented. David demonstrated it to witnesses. He was interviewed later for the book, Biographical and Historical Cyclopedia of Indiana and Armstrong Counties and said: "I may say that there is no connection at all between the telegraph of Morse and others and that of myself...Professor Morse most probably never heard of me or my Elderton telegraph."
[edit] Morse telegraphs
The full potential of the telegraph in America was realized the next year by Samuel Morse and Alfred Vail. Samuel Morse independently developed an electrical telegraph in 1837, an alternative design that was capable of transmitting over long distances using poor quality wire. His assistant, Alfred Vail developed the Morse code signalling alphabet with Morse. The Morse code alphabet commonly used on the device was also named after Morse.
On January 6, 1838 Morse first successfully tested the device at the Speedwell Ironworks near Morristown, New Jersey, and on February 8 he publicly demonstrated it to a scientific committee at the Franklin Institute in Philadelphia, Pennsylvania. The first electric telegram using this device was sent by Morse on May 24, 1844 from Baltimore to Washington, D.C., and sent the message:
- What hath God wrought?
(from the Biblical book of Numbers 23:23: Surely there is no enchantment against Jacob, neither is there any divination against Israel: according to this time it shall be said of Jacob and of Israel, What hath God wrought!).
In 1843 the U.S. Congress appropriated $30,000 to fund an experimental telegraph line from Washington D.C. to Baltimore. By May 1, 1844 the line had been completed to Annapolis Junction. That day the Whig party nominated Henry Clay at its national convention in Baltimore. News of the nomination was hand carried to Annapolis Junction where Vail wired it to Washington.[1] The America's first official telegram was sent by Morse on May 24, 1844 after the line was completed. The Morse/Vail telegraph was quickly deployed in the following two decades. Morse failed to properly credit Henry for the powerful electromagnets used in his telegraph. The original Morse design, without the relay or the "intensity" and "quantity" electromagents invented by Henry only worked to a distance of 40 feet.
This was a practical electrical telegraph system, and subsequently electrical telegraph came to refer to a signaling telegram - a system where an operator makes and breaks an electrical contact with a telegraph key which results in an audible signal at the other end produced by a telegraph sounder which is interpreted and transcribed by a human. Morse and Vail's first telegraphs used a pen and paper system to record the marks of the Morse Code, and interpreted the marks visually however, operators soon realized that they could "read" the clicking of the receiver directly by ear. Systems which automatically read the signals and print formed characters are generally called teletype rather than telegraph systems. Some electrical telegraphs used indicators which were read visually rather than by ear. The most notable of these was the early transatlantic telegraph cable.
[edit] External links
- Morse Telegraph Club, Inc. (The Morse Telegraph Club is an international non-profit organization dedicated to the perpetuation of the knowledge and traditions of telegraphy.)
- http://www.du.edu/~jcalvert/tel/morse/morse.htm
- http://collections.ic.gc.ca/canso/index.htm
- Shilling's telegraph- an exhibit of A.S. Popov Central Museum of Communications
- History of electromagnetic telegraph
- The first electric telegraphs
- The Dawn of Telegraphy- in Russian
- Pavel Shilling and his telegraph- article in PCWeek, russian edition.
- http://atlantic-cable.com/Article/DistantWriting/ A Concise History of the Electric Telegraph Industry in Britain between 1838 and 1868
[edit] References
- Biographical and Historical Cyclopedia of Indiana and Armstrong Counties, by Wiley, Samuel T., editor, John M. Gresham and Co., Philadelphia PA, 1891, pages 475-476.
- W.F. Cooke, The Electric Telegraph, Was it invented by Prof. Wheatstone?, London 1856.
- C.A. Steinheil, Ueber Telegraphie, München 1838.
- C.F. Gauß, Works, Göttingen 1863-1933.da:Elektrisk telegraf
ko:전신 ja:電信 ru:Электрический телеграф sl:Telegraf fi:Lennätin
