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  Telegraph: the telegraph was the first reliable, immediate, long-distance form of communication using electricity. It was developed in Britain and the United States in the 1830s. The telegraph message was sent as an electrical signal via a dedicated switching circuit, which replaced words and numbers with a code, usually Morse code. With the popularization of telephone, fax, etc., the telegraph has been rarely used.

  2020-12-29 喜欢(0) 回复(0)