| The
invention of the telegraph did not come
overnight. On the contrary, it evolved ever since
the beginning of mankind. The earliest forms of
telegraphy were probably smoke, fire, or drum
signals. Much later, discoveries were made that
showed that electric currents and impulses could
be produced and transmitted through a wire. In
the 1780's, Luigi Galvani, an Italian physician,
unknowingly discovered galvanism. Based on the
previous discoveries, Hans Christian Oerst, a
Danish physicist, made another discovery about
electromagnets that influenced the creation of
some primitive telegraphic devices. William
Sturgeon, an English inventor, developed an early
electromagnet in 1825. A few years later, the
American physicist Joseph Henry improved his
design and set up a crude telegraph that sent
signals over more than 1 mile. Later in 1837,
William F. Cooke (an inventor) and Charles
Wheatstone (a physicist) created a telegraph that
used five needles to transmit messages. |
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