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Gutta-percha, a natural polymer similar to rubber, had nearly ideal properties for insulating submarine cables, with the exception of a rather high dielectric constant which made cable capacitance high. Underwater cables, which cannot be kept under constant surveillance, have tempted intelligence-gathering organizations since the late 19th century. Transatlantic cables of the 19th century consisted of an outer layer of iron and later steel wire, wrapping India rubber, wrapping gutta-percha, which surrounded a multi-stranded copper wire at the core. The core can be made of copper, nickel-plated copper or nickel (white metal). Fishing, aging cables and marine species that collide with or become entangled in cables can damage cables and spread toxic and harmful substances into the sea. In the winter of 1854 the French extended the telegraph link to the Black Sea coast. At the start of the campaign there was a telegraph link at Bucharest connected to London. Beyond this, there are particular cable designs that minimize electromagnetic pickup and transmission.

In 1896, there were 30 cable-laying ships in the world, 24 of which were owned by British companies. The British had both supply side and demand side advantages. The geographic location of British territory was also an advantage as it included both Ireland on the east side of the Atlantic Ocean and Newfoundland in North America on the west side, making for the shortest route across the ocean, which reduced costs significantly. From the 1850s until 1911, British submarine cable systems dominated the most important market, the North Atlantic Ocean. The whale was apparently attempting to use the cable to clean off barnacles at a point where the cable descended over a steep drop. Shielding makes use of the electrical principle of the Faraday cage. Conductor material and shapes are regularly improved to increase capacity. Highest capacity system: 12 GW Zhundong-Wannan (准东-皖南)±1100 kV HVDC. The first trans-Pacific telephone cable was laid from Hawaii to Japan in 1964, with an extension from Guam to The Philippines. Also in 1964, the Commonwealth Pacific Cable System (COMPAC), with 80 telephone channel capacity, opened for traffic from Sydney to Vancouver, and in 1967, the South East Asia Commonwealth (SEACOM) system, with 160 telephone channel capacity, opened for traffic.

This system used microwave radio from Sydney to Cairns (Queensland), cable running from Cairns to Madang (Papua New Guinea), Guam, Hong Kong, Kota Kinabalu (capital of Sabah, Malaysia), Singapore, then overland by microwave radio to Kuala Lumpur. Gutta-percha and rubber were not replaced as a cable insulation until polyethylene was introduced in the 1930s. Even then, the material was only available to the military and the first submarine cable using it was not laid until 1945 during World War II across the English Channel. The ROADM is used to improve the reliability of the cable by allowing it to operate even if it has faults. To receive digital cable channels on an analog television set, even unencrypted ones, requires a different type of box, a digital television adapter supplied by the cable company or purchased by the subscriber. An 1863 cable to Bombay (now Mumbai), India, provided a crucial link to Saudi Arabia. Damaged armouring, which was not uncommon, also provided an entrance. A DC link therefore stabilizes the AC grid at either end, since power flow and phase angle can then be controlled independently. In 1858, the steamship Elba was used to lay a telegraph cable from Jersey to Guernsey, on to Alderney and then to Weymouth, the cable being completed successfully in September of that year.

A spin-off from Eastern Telegraph Company was a second sister company, the Eastern Extension, China and Australasia Telegraph Company, commonly known simply as "the Extension." In 1872, Australia was linked by cable to Bombay via Singapore and China and in 1876, the cable linked the British Empire from London to New Zealand. 192-193 Meanwhile, the Electric & International Telegraph Company completed two cables across the North Sea, from Orford Ness to Scheveningen, the Netherlands. 34-36 The same ship was used for the link from Dover to Ostend in Belgium, by the Submarine Telegraph Company. The company later expanded into complete cable manufacture and cable laying, including the building of the first cable ship specifically designed to lay transatlantic cables. 361 The British & Irish Magnetic Telegraph Company completed the first successful Irish link on May 23 between Portpatrick and Donaghadee using the collier William Hutt. In theory, using this partial land route could result in round trip times below 40 ms (which is the speed of light minimum time), and not counting switching. For example, TAT-8 counted 35 participants including most major international carriers at the time such as AT&T Corporation. A major barrier to wider adoption of merchant transmission is the difficulty in identifying who benefits from the facility so that the beneficiaries pay the toll.

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