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The Beginning of Electronic Communications





1. In 1825, British inventor William Sturgeon (1783-1850) exhibited a device that laid the foundations for large-scale electronic communications: the electromagnet. Sturgeon displayed its power by lifting nine pounds with a seven-ounce piece of iron wrapped with wires through which the current of a single cell battery was sent.

In 1830, an American, Joseph Henry (1797-1878), demonstrated the potential of Sturgeon’s device for long distance communication by sending an electronic current over one mile of wire to activate an electromagnet which caused a bell to strike. Thus the electric telegraph was born.

2. Henry’s invention was successfully exploited by Samuel Morse. While a professor of arts and design at New York University in 1835, Samuel Morse proved that signals could be transmitted by wire. He used pulses of current to deflect an electromagnet, which moved a marker to produce written codes on a strip of paper – the invention of Morse Code. The following year, the device was modified to emboss the paper with dots and dashes. He gave a public demonstration in 1838, but it was not until five years later that Congress funded $30,000 to construct an experimental telegraph line from Washington to Baltimore, a distance of 40 miles.

3. Six years later, members of Congress witnessed the sending and receiving of messages over part of the telegraph line. Before the line had reached Baltimore, the Whig party held its national convention there, and on May 1, 1844, nominated Henry Clay. This news was hand-carried to Annapolis Junction, where Morse’s partner, Alfred Vail, wired it to the Capitol. This was the first news dispatched by electric telegraph.

4. The message, "What hath God wrought?" sent later by "Morse Code" from the old Supreme Court chamber in the United States Capitol to his partner in Baltimore, officially opened the completed line of May 24, 1844. Morse’s early system produced a paper copy with raised dots and dashes, which were translated later by an operator.

5. The original Morse telegraph printed code on tape. However, in the United States the operation developed into sending by key and receiving by ear. A trained Morse operator could transmit 40 to 50 words per minute. Automatic transmission, introduced in 1914, handled more than twice that number.

In 1913 Western Union developed multiplexing, which made it possible to transmit eight messages simultaneously over a single wire (four in each direction). Teleprinter machines came into use about 1925. Varioplex, introduced in 1936, enabled a single wire to carry 72 transmissions at the same time (36 in each direction). Two years later Western Union introduced the first of its automatic facsimile devices. In 1959 Western Union inaugurated TELEX, which enables subscribers to the teleprinter service to dial each other directly.

Until 1877, all rapid long-distance communication depended upon the telegraph. That year, a rival technology developed that would again change the face of communication – the telephone.

6. By 1879, patent litigation between Western Union and the infant telephone system was ended in an agreement that largely separated the two services.

Samuel Morse is best known as the inventor of the telegraph, but he is also esteemed for his contributions to American portraiture. His painting is characterized by delicate technique and vigorous honesty and insight into the character of his subjects.

 

Date: 2016-07-18; view: 241; Нарушение авторских прав; Помощь в написании работы --> СЮДА...



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