Cooke and Wheatstone system The first commercial electrical telegraph was the
Cooke and Wheatstone system. A demonstration four-needle system was installed on the
Euston to
Camden Town section of
Robert Stephenson's
London and Birmingham Railway in 1837 for signalling rope-hauling of locomotives. It was rejected in favour of pneumatic whistles. Cooke and Wheatstone had their first commercial success with a system installed on the
Great Western Railway over the from
Paddington station to
West Drayton in 1838. This was a five-needle, six-wire
Wheatstone ABC telegraph -powered Wheatstone A. B. C. telegraph with the horizontal "communicator" dial, the inclined "indicator" dial and crank handle for the magneto that generated the electrical signal. Wheatstone developed a practical alphabetical system in 1840 called the A.B.C. System, used mostly on private wires. This consisted of a "communicator" at the sending end and an "indicator" at the receiving end. The communicator consisted of a circular dial with a pointer and the 26 letters of the alphabet (and four punctuation marks) around its circumference. Against each letter was a key that could be pressed. A transmission would begin with the pointers on the dials at both ends set to the start position. The transmitting operator would then press down the key corresponding to the letter to be transmitted. In the base of the communicator was a
magneto actuated by a handle on the front. This would be turned to apply an alternating voltage to the line. Each half cycle of the current would advance the pointers at both ends by one position. When the pointer reached the position of the depressed key, it would stop and the magneto would be disconnected from the line. The communicator's pointer was geared to the magneto mechanism. The indicator's pointer was moved by a polarised electromagnet whose
armature was coupled to it through an
escapement. Thus the alternating line voltage moved the indicator's pointer on to the position of the depressed key on the communicator. Pressing another key would then release the pointer and the previous key, and re-connect the magneto to the line. These machines were very robust and simple to operate, and they stayed in use in Britain until well into the 20th century.
Morse system "WHAT HATH GOD WROUGHT"on 24 May 1844 The Morse system uses a single wire between offices. At the sending station, an operator taps on a switch called a
telegraph key, spelling out text messages in
Morse code. Originally, the armature was intended to make marks on paper tape, but operators learned to interpret the clicks and it was more efficient to write down the message directly. In 1851, a conference in Vienna of countries in the German-Austrian Telegraph Union (which included many central European countries) adopted the Morse telegraph as the system for international communications. The
international Morse code adopted was considerably modified from the original
American Morse code, and was based on a code used on Hamburg railways (
Gerke, 1848). A common code was a necessary step to allow direct telegraph connection between countries. With different codes, additional operators were required to translate and retransmit the message. In 1865, a conference in Paris adopted Gerke's code as the International Morse code and was henceforth the international standard. The US, however, continued to use American Morse code internally for some time, hence international messages required retransmission in both directions. In the United States, the Morse/Vail telegraph was
quickly deployed in the two decades following the first demonstration in 1844. 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.
Foy–Breguet system displaying the letter "Q" France was slow to adopt the electrical telegraph, because of the extensive
optical telegraph system built during the
Napoleonic era. There was also serious concern that an electrical telegraph could be quickly put out of action by enemy saboteurs, something that was much more difficult to do with optical telegraphs which had no exposed hardware between stations. The
Foy-Breguet telegraph was eventually adopted. This was a two-needle system using two signal wires but displayed in a different way than other needle telegraphs. The needles made symbols similar to the
Chappe optical system symbols, making it more familiar to the telegraph operators. The optical system was decommissioned starting in 1846, but not completely until 1855. In that year the Foy-Breguet system was replaced with the Morse system.
Expansion 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. Telegraph networks were expensive to build, but financing was readily available, especially from London bankers. By 1852, National systems were in operation in major countries: The New York and Mississippi Valley Printing Telegraph Company, for example, was created in 1852 in Rochester, New York and eventually became the
Western Union Telegraph Company. Although many countries had telegraph networks, there was no
worldwide interconnection. Message by post was still the primary means of communication to countries outside Europe. Telegraphy was introduced in
Central Asia during the 1870s.
Telegraphic improvements A continuing goal in telegraphy was to reduce the cost per message by reducing hand-work, or increasing the sending rate. There were many experiments with moving pointers, and various electrical encodings. However, most systems were too complicated and unreliable. A successful expedient to reduce the cost per message was the development of
telegraphese. The first system that did not require skilled technicians to operate was Charles Wheatstone's ABC system in 1840 in which the letters of the alphabet were arranged around a clock-face, and the signal caused a needle to indicate the letter. This early system required the receiver to be present in real time to record the message and it reached speeds of up to 15 words a minute. In 1846,
Alexander Bain patented a chemical telegraph in Edinburgh. The signal current moved an iron pen across a moving paper tape soaked in a mixture of ammonium nitrate and potassium ferrocyanide, decomposing the chemical and producing readable blue marks in Morse code. The speed of the printing telegraph was 16 and a half words per minute, but messages still required translation into English by live copyists. Chemical telegraphy came to an end in the US in 1851, when the Morse group defeated the Bain patent in the US District Court. For a brief period, starting with the New York–Boston line in 1848, some telegraph networks began to employ sound operators, who were trained to understand Morse code aurally. Gradually, the use of sound operators eliminated the need for telegraph receivers to include register and tape. Instead, the receiving instrument was developed into a "sounder", an electromagnet that was energized by a current and attracted a small iron lever. When the sounding key was opened or closed, the sounder lever struck an anvil. The Morse operator distinguished a dot and a dash by the short or long interval between the two clicks. The message was then written out in long-hand.
Royal Earl House developed and patented a letter-printing telegraph system in 1846 which employed an alphabetic keyboard for the transmitter and automatically printed the letters on paper at the receiver, and followed this up with a steam-powered version in 1852. Advocates of printing telegraphy said it would eliminate Morse operators' errors. The House machine was used on four main American telegraph lines by 1852. The speed of the House machine was announced as 2600 words an hour.
David Edward Hughes invented the printing telegraph in 1855; it used a keyboard of 26 keys for the alphabet and a spinning type wheel that determined the letter being transmitted by the length of time that had elapsed since the previous transmission. The system allowed for automatic recording on the receiving end. The system was very stable and accurate and became accepted around the world. The next improvement was the
Baudot code of 1874. French engineer
Émile Baudot patented a printing telegraph in which the signals were translated automatically into typographic characters. Each character was assigned a five-bit code, mechanically interpreted from the state of five on/off switches. Operators had to maintain a steady rhythm, and the usual speed of operation was 30 words per minute. By this point, reception had been automated, but the speed and accuracy of the transmission were still limited to the skill of the human operator. The first practical automated system was patented by Charles Wheatstone. The message (in
Morse code) was typed onto a piece of perforated tape using a keyboard-like device called the 'Stick Punch'. The transmitter automatically ran the tape through and transmitted the message at the then exceptionally high speed of 70 words per minute.
Teleprinters ASR (Automatic Send and Receive) 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 onto 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. 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. In 1901, Baudot's code was modified by
Donald Murray. In the 1930s, teleprinters were produced by
Teletype in the US,
Creed in Britain and
Siemens in Germany. 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 resulting systems 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.
The harmonic telegraph The most expensive aspect of a telegraph system was the installation – the laying of the wire, which was often very long. The costs would be better covered by finding a way to send more than one message at a time through the single wire, thus increasing revenue per wire. Early devices included the
duplex and the
quadruplex which allowed, respectively, one or two telegraph transmissions in each direction. However, an even greater number of channels was desired on the busiest lines. In the latter half of the 1800s, several inventors worked towards creating a method for doing just that, including
Charles Bourseul,
Thomas Edison,
Elisha Gray, and
Alexander Graham Bell. One approach was to have resonators of several different frequencies act as carriers of a modulated on-off signal. This was the harmonic telegraph, a form of
frequency-division multiplexing. These various frequencies, referred to as harmonics, could then be combined into one complex signal and sent down the single wire. On the receiving end, the frequencies would be separated with a matching set of resonators. With a set of frequencies being carried down a single wire, it was realized that the human voice itself could be transmitted electrically through the wire. This effort led to the
invention of the telephone. (While the work toward packing multiple telegraph signals onto one wire led to telephony, later advances would pack multiple voice signals onto one wire by increasing the bandwidth by modulating frequencies much higher than human hearing. Eventually, the bandwidth was widened much further by using laser light signals sent through fiber optic cables. Fiber optic transmission can carry 25,000 telephone signals simultaneously down a single fiber.)
Oceanic telegraph cables Soon after the first successful telegraph systems were operational, the possibility of transmitting messages across the sea by way of
submarine communications cables was first proposed. One of the primary technical challenges was to sufficiently insulate the submarine cable to prevent the electric current from leaking out into the water. In 1842, a Scottish surgeon
William Montgomerie introduced
gutta-percha, the adhesive juice of the
Palaquium gutta tree, to Europe.
Michael Faraday and Wheatstone soon discovered the merits of gutta-percha as an insulator, and in 1845, the latter suggested that it should be employed to cover the wire which was proposed to be laid from
Dover to
Calais. Gutta-percha was used as insulation on a wire laid across the
Rhine between
Deutz and
Cologne. In 1849,
C. V. Walker, electrician to the
South Eastern Railway, submerged a wire coated with gutta-percha off the coast from Folkestone, which was tested successfully. John Pender, one of the men on the Great Eastern, later founded several telecommunications companies primarily laying cables between Britain and Southeast Asia. Earlier transatlantic
submarine cables installations were attempted in 1857, 1858 and 1865. The 1857 cable only operated intermittently for a few days or weeks before it failed. The study of underwater telegraph cables accelerated interest in mathematical analysis of very long
transmission lines. The telegraph lines from Britain to India were connected in 1870. (Those several companies combined to form the
Eastern Telegraph Company in 1872.) The HMS
Challenger expedition in 1873–1876 mapped the ocean floor for future underwater telegraph cables. Australia was first linked to the rest of the world in October 1872 by a submarine telegraph cable at Darwin. This brought news reports from the rest of the world. The telegraph across the Pacific was completed in 1902, finally encircling the world. From the 1850s until well into the 20th century, British submarine cable systems dominated the world system. This was set out as a formal strategic goal, which became known as the
All Red Line. In 1896, there were thirty cable laying ships in the world and twenty-four of them were owned by British companies. In 1892, British companies owned and operated two-thirds of the world's cables and by 1923, their share was still 42.7 percent.
Cable and Wireless Company Cable & Wireless was a British telecommunications company that traced its origins back to the 1860s, with Sir
John Pender as the founder, although the name was only adopted in 1934. It was formed from successive mergers including: • The Falmouth, Malta, Gibraltar Telegraph Company • The British Indian Submarine Telegraph Company • The Marseilles, Algiers and Malta Telegraph Company • The Eastern Telegraph Company • The Eastern Extension Australasia and China Telegraph Company • The Eastern and Associated Telegraph Companies ==Telegraphy and longitude==