Telegraph

The electric telegraph is a communication system that made it possible to send coded messages over long distances using electrical signals. Earlier forms of telegraphy existed, but the electric telegraph became practical during the 19th century as engineers learned to control electrical currents and transmit them through wires. In the 1830s, the American inventor Samuel Morse and his collaborators developed a practical telegraph system and a code in which letters and numbers were represented by combinations of dots and dashes.

The first successful long-distance demonstration of Morse's system took place in 1844, when a message was sent between Washington, D.C., and Baltimore. Telegraph networks then expanded rapidly across countries and, later, between continents through submarine cables. A telegraph operator entered a message using a key that opened and closed an electrical circuit. The resulting pulses traveled through a wire to a distant receiving station, where an instrument recorded or indicated the pattern of the signals.

The recipient could then decode the message into words. Telegraphy greatly reduced the time needed to communicate information over long distances, which had previously depended on physical transport by people, ships or other means. It became important for newspapers, businesses, governments, railways and financial services. Telegraph networks also helped coordinate railway traffic and transmit urgent information.

Although the telephone and later radio, television and the internet offered faster or more convenient forms of communication, the telegraph marked a major change in human history: information could travel electrically across great distances in a matter of minutes rather than days or weeks.