| 单词 | telegraph |
| 释义 | telegraph From the Greek tele, meaning far off, and graphos, meaning written. See also Hellenologophobia. 1. An apparatus or process for communicating information over a distance by coded signals. Simple telegraphs employ smoke signals, drums, mirrors, flags, fires, lanterns, and mechanical semaphores. 2. The electric telegraph was invented by Samuel F.B. Morse (1791–1872) and Alfred Vail (1807–1859), and the first intercity telegraph line in the United States began operation in 1844. That system involved a transmitter, or sender, in the form of a manually operated telegraph key that the operator used to open and close an electric circuit, thereby sending coded alphanumeric data using Morse code.The receiver recorded the code symbols with an armature that scratched a paper tape. The manual key has been improved, and now operates on the basis of a side-to-side motion, which is more natural than an up-and-down motion. The receiver eliminated the armature, and became a simple sounder that emits audible clicks, for which the human operator must listen to decode the transmission. Note: In 1838, Samuel Morse offered to give his invention of the telegraph to the newly formed (1836) Republic of Texas. After having received no reply for 22 years, Morse withdrew his offer in a letter to Texas governor Sam Houston in 1860. See also ham; Morse Code; Morse, Samuel F.B. ; Pony Express; teletype; Telex; Vail, Alfred; and Western Union. |
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