A telegraph is any system that transmits encoded information by signal across a distance. Although it is associated with sending messages via an electric current, the word telegraph was coined to describe an optical system of sending coded messages. From its invention until the telephone became a viable system, the telegraph was the standard means of communicating both between and within metropolitan areas in both Europe and the United States. Telephones did not make the telegraph obsolete but rather complemented it for many decades. Telegrams and telexes used telegraphy but are rapidly being replaced by facsimile (fax) transmissions through telephone lines. Satellite transmission and high-frequency radio bands are used for international telegraphy.
The earliest forms of sending messages over distances were probably both visual and acoustic. Smoke signals by day and beacon fires by night were used by the ancient people of China, Egypt, and Greece. Drum beats extended the range of the human voice and are known to have sent messages as have reed pipes and the ram's horn. The Greek poet Aeschylus (c. 525-c. 455 B.C.) described nine beacon fires used on natural hills that could communicate over 500 mi (805 km), and the Greek historian, Polybius (c. 200-c. 118 B.C.), recounted a visual code that was used to signal the 24-letter Greek alphabet. It is also known that Native Americans used signal fires before colonial times and later. Visual systems had a greater range than ones that depended on being heard, and they were greatly stimulated by the seventeenth century invention of the telescope.
In 1791, the French engineer Claude Chappe (1763-1805) and his brother Ignace (1760-1829) invented the semaphore, an optical telegraph system that relayed messages from hilltop to hilltop using telescopes. The Chappes built a series of two-arm towers between cities. Each tower was equipped with telescopes pointing in either direction and a cross at its top whose extended arms could each assume seven easily-seen angular positions. Together, they could signal all the letters of the French alphabet as well as some numbers. Their system was successful and soon was duplicated elsewhere in Europe. It was Chappe who coined the word telegraph. He combined the Greek words tele meaning distance and graphien meaning to write, to define it as "writing at a distance." Its shortcomings however were its dependence on good weather and its need for a large operating staff. Advances in electricity would soon put this system out of business.
It was the invention of the battery and the resultant availability of electric charges moving at 186,000 mi (299,460 km) a second that accomplished this. Prior to this invention by the Italian physicist Alessandro Giuseppe A. A. Volta (1745-1827) in 1800, attempts to use electricity to communicate had failed because a dependable source of electricity was not available and the long, iron wires needed did not conduct electricity well and could not be properly insulated. Volta's new battery meant that experimenters had for the first time a reliable current of sufficient strength to transmit signals. The next major development was in 1819 when the Danish physicist Hans Christian Oersted (1777-1851) demonstrated that he could use an electric current to deflect a magnetic needle. Further, he showed that the direction of the movement depended on the direction of the flow of the current. This pointed the way to the true telegraph. While several researchers in different countries were attempting to exploit the communications aspects of this discovery, two Englishmen, William Fothergill Cooke (1806-1879) and Charles Wheatstone (1802-1875), formed a partnership and designed a five-needle telegraph system in 1837. Their system used needles to point to letters of the alphabet and numbers that were arranged on a panel. Their electric telegraph was immediately put to use on the British railway system. This system was used primarily for railroad signalling until 1845 when an event raised the public's awareness of the potential of the telegraph. On New Year's Day, 1845, the telegraph was used to catch a murderer who had been seen boarding a train bound for London. The information was telegraphed ahead and the murderer was arrested, tried, and hanged.
Although Cooke and Wheatstone built the first successful telegraph based on electricity, it was an American artist and inventor, Samuel Finley Breese Morse (1791-1872), who would devise a telegraph method that would eventually become universally adopted. Morse had begun investigating telegraphy at about the same time as his English rivals, but he had no scientific background and was getting nowhere until he was informed about the 1825 invention of the electromagnet that had been made by the English physicist William Sturgeon (1783-1850). Fortunately for Morse, he took his inquiries to the American physicist Joseph Henry (1797-1878), who had built in 1831 an extremely powerful electromagnet (it could lift 750 lb [341 kg] compared to Sturgeon's 9 lb [4.1 kg]). More importantly, Henry had successfully experimented with using the electromagnet to transmit signals and clearly understood what would become the fundamental principle of the telegraph—the opening and closing of an electric circuit supplied by a battery. Henry gladly enlightened Morse on the mysteries of electromagnetism, and the determined Morse took it from there. He enlisted the aid of a young mechanic, Alfred Vail, and together they improved on the work Morse had already started. These early attempts using an electromagnet resulted in a pen touching a moving piece of paper to record a series of dots and dashes. This system presumes a coded message, and Morse had created his own system which, when he collaborated with Vail, resulted in the now-famous Morse code. Vail contributed significantly to the code, having visited a printer to determine which letters were most and least often used. Their code was then based on the most common letters having the simplest, shortest of symbols (dots and dashes). By 1837, they had put together a system which used a single, simple operator key which, when depressed, completed an electric circuit and sent a signal to a distant receiver over a wire. Their first public demonstration was made at Vail's shop in Morristown, New Jersey, and in 1843, the U. S. Government appropriated funds to build a pole line spanning the 37 mi (59.5 km) between Baltimore, Maryland and Washington, D.C. On May 24, 1844, the historic message, "What hath God wrought?" was sent and received. Once the system became practiced, it was found that skilled operators could "read" a message without looking at the dots and dashes on the paper by simply listening to the sound of the electromagnet's clicking. This led to the elimination of the paper and an even simpler electric telegraph system that used only a key, battery, pole line, and a new sounder to make the dot or dash clicking sound clear. Using such simple equipment and a single, insulated copper wire, Morse's telegraph system spread quickly across the United States and eventually replaced the older, English versions in Europe.
As the telegraph system grew and spread across the world, improvements followed fairly quickly. One of the first was Morse's development of a relay system to cover longer distances. His relay used a series of electromagnet receivers working on low current, each of which opened and shut the switch of a successive electric circuit supplied by its own battery. Telegraph use increased with the invention in Germany of the duplex circuit, allowing messages to travel simultaneously in opposite directions on the same line. In 1874, American inventor Thomas Alva Edison (1847-1931) designed a double duplex called a quadruplex. This higher-capacity system needed eight operators who handled four messages at one time, two in each direction. A high-speed automatic Morse system also had been invented by Wheatstone in 1858, whose punched-paper tape idea offered a means by which a message could be stored and sent by a high speed transmitter that could read the holes in the tape. This system could transmit up to 600 words per minute. The most revolutionary and innovative improvement however was a time-division, multiplex-printing telegraph system devised in 1872 by the French engineer, Jean Maurice Emile Baudot (1845-1903). His system was based on his new code which replaced the Morse code. It employed a five-unit code whose every character contained five symbol elements. The heart of his system was a distributor consisting of a stationary faceplate of concentric copper rings that were swept by brushes mounted on a rotating assembly. This logical system greatly increased the traffic capacity of each line and was so far ahead of its time that it contained many elements from which modern systems have evolved.
By the end of the nineteenth century, most of the world was connected by telegraph lines, including several cables that crossed the Atlantic Ocean. The first underwater conductor was laid by Morse in New York Harbor in 1842. Insulated with India rubber, it did not last long. After the German-English inventor, William Siemans (1823-1883) devised a machine to apply gutta-percha as insulation in 1847, submarine cables were laid across the English Channel from Dover, England to Calais, France in 1850-51. Unsuccessful attempts to span the Atlantic were made in 1857, 1858, and 1865, all under the guidance of American entrepreneur, Cyrus West Field (1819-1892). On July 27, 1866, Field was successful in his fourth attempt, and having connected the United States to Europe, he immediately returned to sea, recovered the lost 1865 cable, and had a second transatlantic telegraph cable working that same year. By 1940 there were 40 transatlantic cables in operation. Ten years later, some of these began to fail and were not repaired for economic reasons. In 1956, transatlantic telephone cables were first laid, and in 1966, the last of the exclusively telegraph cables were abandoned.
Throughout its history, the telegraph proved especially useful to the military. It was first used for these purposes in 1854 by the Allied Army in Bulgaria during the Crimean War. A transcontinental telegraph line had been completed in the United States just as the Civil War began, and the telegraph proved enormously useful to both sides. During the Spanish-American War in 1898, undersea telegraph cables were cut as an act of belligerency for the first time, and in World War I, teleprinters with secret codes were heavily used by all combatants.
The earliest teleprinter was invented by an American, Royal E. House, in 1846, only two years after Morse's first success. The transmitter had 28 character keys and employed a fairly crude system that even had a hand crank. Although it was used for only a few years, it was the forerunner of both the teleprinter and the stock ticker. At the turn of the century, a Nova Scotia inventor, Frederick G. Creed (1871-1957), experimented in Scotland with using a typewriter to send printed messages without using the Morse Code. His teleprinter system did not catch on in England, and in 1907, Charles L. Krumm of the United States designed the prototype version of the modern teleprinter. This system was subsequently improved, and during the 1920s became known by the American Telephone and Telegraph trade name, Teletype. Commercial teleprinter exchange services called TRX and Telex were developed during the next decade that were capable of printing up to 500 characters per minute. By 1964, this was up to 900 characters per minute. By then, technical improvements in the telephone had made an entire new range of technology available to telegraphy, and today, the telegraph has evolved into a modern digital data-transmission system. Today's modern systems use television coaxial cables, microwave, optical fiber, and satellite links to achieve an extremely high transmission rate.
The invention of the telegraph could in some ways be seen as the real beginning of our modern age, given the way in which it so interconnected the entire world. Almost coincidental with its birth there was the emergence of a new kind of journalism that made currency its stock in trade. Reporting events that had only just occurred took precedence over a newspaper's traditional editorial role, and news was reported almost as soon as it happened. Corporations also could become larger and more far-flung, and nations became necessarily more interdependent. With the telegraph, information—in all its aspects and forms—began to assume the critical role it plays today.
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Israel, Paul. From Machine Shop to Industrial Laboratory: Telegraphy and the Changing Context of American Invention. Baltimore: Johns Hopkins University Press, 1992.
Leonard C. Bruno