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  2. Smoke signal - Wikipedia

    en.wikipedia.org/wiki/Smoke_signal

    The smoke signal is one of the oldest forms of long-distance communication. It is a form of visual communication used over a long distance. In general smoke signals are used to transmit news, signal danger, or to gather people to a common area.

  3. Garrett Morgan - Wikipedia

    en.wikipedia.org/wiki/Garrett_Morgan

    Garrett Augustus Morgan Sr. (March 4, 1877 – July 27, 1963) was an American inventor, businessman, and community leader.His most notable inventions were a type of three-way traffic light, [1] and a protective 'smoke hood' [2] notably used in a 1916 tunnel construction disaster rescue.

  4. History of telecommunication - Wikipedia

    en.wikipedia.org/wiki/History_of_telecommunication

    The history of telecommunication began with the use of smoke signals and drums in Africa, Asia, and the Americas. In the 1790s, the first fixed semaphore systems emerged in Europe. However, it was not until the 1830s that electrical telecommunication systems started to appear. This article details the history of telecommunication and the ...

  5. Telecommunications - Wikipedia

    en.wikipedia.org/wiki/Telecommunications

    Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph, telephone, television, and radio. Early telecommunication networks used metal wires as the medium for transmitting signals. These networks were used for telegraphy and telephony for many decades.

  6. Telegraphy - Wikipedia

    en.wikipedia.org/wiki/Telegraphy

    Smoke signals, for instance, are to be considered semaphore, not telegraph. According to Morse, telegraph dates only from 1832 when Pavel Schilling invented one of the earliest electrical telegraphs.

  7. Polybius square - Wikipedia

    en.wikipedia.org/wiki/Polybius_square

    The Polybius square, also known as the Polybius checkerboard, is a device invented by the ancient Greeks Cleoxenus and Democleitus, and made famous by the historian and scholar Polybius. [1] The device is used for fractionating plaintext characters so that they can be represented by a smaller set of symbols, which is useful for telegraphy ...

  8. Smoke detector - Wikipedia

    en.wikipedia.org/wiki/Smoke_detector

    The photoelectric (optical) smoke detector was invented by Donald Steele and Robert Emmark from Electro Signal Lab and patented in 1972. [ 15 ] In 1995, the 10-year-lithium-battery-powered smoke alarm was introduced.

  9. Electrical telegraph - Wikipedia

    en.wikipedia.org/wiki/Electrical_telegraph

    Prior to the electric telegraph, visual systems were used, including beacons, smoke signals, flag semaphore, and optical telegraphs for visual signals to communicate over distances of land. [ 6 ] An auditory predecessor was West African talking drums .