Electromagnetic communication device. In 1832 Samuel F.B. Morse made sketches of ideas for a system of electric telegraphy, and in 1835 he developed a code to represent letters and numbers (Morse code). In 1837 he was granted a patent on an electromagnetic telegraph that transmitted signals along a wire. That same year British inventors patented a telegraph system that activated five needle pointers that could be made to point to specific letters and numbers on their mounting plate. Public use of Morse's telegraph system began in 1844 and lasted more than 100 years. By the late 20th century the telegraph had been replaced in most applications in developed countries by digital data transmission systems based on computer technology. See also Western Union Corp.

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