article

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 practical apparatus of such kind was set up in the apartment of Russian inventor Pavel Shilling in St.Petersburg, in 1832.

History

Early works and messages

In 1775 Francisco de Salva offered an electrostatical telegraph. Telegraphy based on static electricity was impractical because of the high voltages required. Volta invented the Voltaic Pile in 1800, allowing a continuous current for experimentation. Samuel T. Soemmering constructed his electrochemical telegraph in 1809. Oersted 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 Henry invented the relay, by which a weak current over long wires could operate a powerful local electromagnet.

The first commercial electrical telegraph was constructed by Sir Charles Wheatstone and Sir William Fothergill Cooke and entered use on the Great Western Railway. Wheatstone and Cooke 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. It was patented in the United Kingdom in 1837. 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.

Transatlantic era

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.

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.

In 1867, David Brooks (while working for the Central Pacific Railroad) was awarded (March 26) and (October 9) for his improvements to telegraph insulators. He was also awarded reissue number 2,717 on August 6, 1867, for , 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 (, "Duplex Telegraph") . On January 27, 2006, Western Union discontinued all telegram and commercial messaging services, though it still offer its money transfer services.

Global communication

Within 29 years of its invention, 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 boom.

Shilling telegraphs

The telegraph invented by Baron Schilling in 1832 had a transmitting instrument 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, Shilling demonstrated the long-distance transmission of signals by positioning two telegraphs of his invention in two different rooms of his apartment. In 1836 the Shilling'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. Shilling also was the first to put into practice the idea of the binary system of signal transmission.

Alter and the Elderton Telegraph

Across the Atlantic 1836, a Americian 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."

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.

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.* The America's first official telegram was sent by Morse on May 24, 1844 after the line was completed. He sent the message, "What hath God wrought," from Washington to Baltimore. 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.

On January 6, 1838 Morse first successfully tested the device 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 said:

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!).

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.

External links

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.

Electrical Telegraph | Telecommunications history

Elektrisk telegraf | 電信 | Электрический телеграф | Telegraf | Lennätin

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Electrical telegraph".

Home Page • arts • business • computers • games • health • hospitals • home • kids & teens • news • physicians • recreation• reference • regional • science • shopping • society • sports • world