History of the Telegraph

An electrical telegraph is a telegraph that uses electrical signals, usually conveyed via dedicated telecommunication lines or radio.

The electrical telegraph, or more commonly just telegraph, superseded optical semaphore telegraph systems, thus becoming the first form of electrical telecommunications. In a matter of decades after their creation in the 1830s, electrical telegraph networks permitted people and commerce to transmit messages across both continents and oceans almost instantly, with widespread social and economic impacts.

Commercial Telegraphy

The first commercial electrical telegraph, the Cooke and Wheatstone telegraph, was co-developed by William Fothergill Cooke and Charles Wheatstone. In May 1837 they patented a telegraph system which used a number of needles on a board that could be moved to point to letters of the alphabet. The patent recommended a five-needle system, but any number of needles could be used depending on the number of characters it was required to code. A four-needle system was installed between Euston and Camden Town in London on a rail line being constructed by Robert Stephenson between London and Birmingham. It was successfully demonstrated on 25 July 1837. Euston needed to signal to an engine house at Camden Town to start hauling the locomotive up the incline. As at Liverpool, the electric telegraph was in the end rejected in favour of a pneumatic system with whistles.

Cooke and Wheatstone had their first commercial success with a system installed on the Great Western Railway over the 13 miles (21 km) from Paddington station to West Drayton in 1838, the first commercial telegraph in the world. This was a five-needle, six-wire system. The cables were originally installed underground in a steel conduit. However, the cables soon began to fail as a result of deteriorating insulation and were replaced with uninsulated wires on poles. As an interim measure, a two-needle system was used with three of the remaining working underground wires, which despite using only two needles had a greater number of codes. But when the line was extended to Slough in 1843, a one-needle, two-wire system was installed.

From this point the use of the electric telegraph started to grow on the new railways being built from London. The London and Blackwall Railway (another rope-hauled application) was equipped with the Cooke and Wheatstone telegraph when it opened in 1840, and many others followed. The one-needle telegraph proved highly successful on British railways, and 15,000 sets were still in use at the end of the nineteenth century. Some remained in service in the 1930s. In September 1845 the financier John Lewis Ricardo and Cooke formed the Electric Telegraph Company, the first public telegraphy company in the world. This company bought out the Cooke and Wheatstone patents and solidly established the telegraph business.

Morse System

In the United States, the Morse/Vail telegraph was quickly deployed in the two decades following the first demonstration. The overland telegraph connected the west coast of the continent to the east coast by 24 October 1861, bringing an end to the Pony Express.

As well as the rapid expansion of the use of the telegraphs along the railways, they soon spread into the field of mass communication with the instruments being installed in post offices. The era of mass personal communication had begun.

Teleprinters

An early successful teleprinter was invented by Frederick G. Creed. In Glasgow he created his first keyboard perforator, which used compressed air to punch the holes. He also created a reperforator (receiving perforator) and a printer. The reperforator punched incoming Morse signals on to paper tape and the printer decoded this tape to produce alphanumeric characters on plain paper. This was the origin of the Creed High Speed Automatic Printing System, which could run at an unprecedented 200 words per minute. His system was adopted by the Daily Mail for daily transmission of the newspaper contents.

By the 1930s teleprinters were being produced by Teletype in the US, Creed in Britain and Siemens in Germany.

With the invention of the teletypewriter, telegraphic encoding became fully automated. Early teletypewriters 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.

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 ITA2. This "type A" Telex routing functionally automated message routing.

The first wide-coverage Telex network was implemented in Germany during the 1930s as a network used to communicate within the government.

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.

End of the Telegraph Era

In the United States, Western Union discontinued all telegram and commercial messaging services on 27 January 2006, although it still offered its electronic money transfer services.

India's state-owned telecom company, BSNL, ended its telegraph service on 14 July 2013. It was reportedly the world's last existing true electric telegraph system.

https://en.wikipedia.org/wiki/Electrical_telegraph