Popular Science Monthly/Volume 24/February 1884/Under-Ground Wires > 커뮤니티 카카오소프트 홈페이지 방문을 환영합니다.

In the final ring circuit, each socket-outlet was supplied with current by conductors on both sides of the 'loop.' This contrasts with the radial circuit system (which is also used in the UK, often in the same installation) wherein a single cable runs out radially, like a spoke, from the distribution board to serve a number of sockets. In this way hundreds of single wires would be gathered into small and inoffensive cables, and the enormous wooden structures would be replaced by small cable supports of brick or iron. This was a two-needle system using two signal wires but displayed in a uniquely different way to other needle telegraphs. Later in the same year, instead of a voltaic pile, Gauss used an induction pulse, enabling him to transmit seven letters a minute instead of two. By 1837, William Fothergill Cooke and Charles Wheatstone had co-developed a telegraph system which used a number of needles on a board that could be moved to point to letters of the alphabet. Pavel Schilling subsequently improved its apparatus by reducing the number of connecting wires from eight to two. The main report listed eight points to consider in deciding the design of the new standard.

In 1836, the British government attempted to buy the design but Schilling instead accepted overtures from Nicholas I of Russia. The first telegram in the United States was sent by Morse on 11 January 1838, across two miles (3 km) of wire at Speedwell Ironworks near Morristown, New Jersey, although it was only later, in 1844, that he sent the message "WHAT HATH GOD WROUGHT" over the 44 miles (71 km) from the Capitol in Washington to the old Mt. Clare Depot in Baltimore. Standardization in the field of cables is performed by the group ISO /IEC JTC1/ SC25/WG3 international and national organizations such as the TIA / EIA (Electronic Industries Association/Telecommunications Industries Association) in the United States. The first thermoplastic used was gutta-percha (a natural latex) which was found useful for underwater cables in the 19th century. In 1849 Mr. C. V. Walker, electrician to the South Eastern Railway Company, submerged a wire coated with it, or, as it is technically called, a gutta-percha core, along the coast off Dover. 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.

The Electric Telegraph Company, the world's first public telegraphy company, was formed in 1845 by financier John Lewis Ricardo and Cooke. Samuel Morse independently developed and patented a recording electric telegraph in 1837. Morse's assistant Alfred Vail developed an instrument that was called the register for recording the received messages. The lines were connected at both ends to revolving dials marked with the letters of the alphabet and electrical impulses sent along the wire were used to transmit messages. At the sending station, an operator taps on a switch called a telegraph key, spelling out text messages in Morse code. When at the starting station the operator pressed a key, the corresponding pointer was deflected at the receiving station. Pressing another key would then release the pointer and the previous key, and re-connect the magneto to the line. When the pointer reached the position of the depressed key, it would stop and the magneto would be disconnected from the line. Thus the alternating line voltage moved the indicator's pointer on to the position of the depressed key on the communicator. A transmission would begin with the pointers on the dials at both ends set to the start position. At the family home on Hammersmith Mall, he set up a complete subterranean system in a 175-yard (160 m) long trench as well as an eight-mile (13 km) long overhead telegraph.

• The pairs are covered in a foil or braided mesh, as well as outer PVC jacket. These were clearly recognisable as two-pin plugs and sockets, but with no indication as to pin size or spacing, they were sold as pairs. Adaptors were available from 15 A down to 5 A and from 5 A down to 2 A so in practice it was possible for an appliance with the smallest size of flex to be protected only by a 15 A fuse. A fuse that worked loose could end up protruding from the socket, electrically live and posing a shock hazard, when the plug was removed. This plug corresponds to Type D in the IEC table. • Configuration In a single pair configuration; the pair of wires is enclosed in a sheath or jacket, made of polyethylene, poly vinyl chloride or Teflon. Slough in 1843, the system was converted to a one-needle, two-wire configuration with uninsulated wires on poles. 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. The Morse system uses a single wire between offices. In 1825, William Sturgeon 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.

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