Telegraph:
  • Telegraph, a device or system that allows the transmission of information by coded signal over distance.
  • It was invented by Samuel Morse in 1840.
  • It worked by transmitting electrical signals over a wire laid between stations.
  • In addition to helping invent the telegraph, Samuel Morse developed a code  that assigned a set of dots and dashes to each letter of the English alphabet and allowed for the simple transmission of complex messages across telegraph lines.
  • All the system needed was a key, a battery, wire and a line of poles between stations for the wire and a receiver.
  • This is the Morse’s original telegraph machine. It is constructed from a canvas stretcher and wooden gears and is powered by a homemade battery.
Morse code:
  • Morse code is a code which is used for communication which contains series of dots and dashes to represent alphabets, numbers and symbols.
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     Using of morse code in telegraph system:
  • Before telephones were invented, it could send messages over long distances by using pulses of electricity to signal a machine to make marks on a moving paper tape called telegraph system.
  • A code was necessary to help translate the marks on the paper tape into readable text messages.
  • The dot duration is the basic unit of time measurement in code transmission.
  • The duration of a dash is three times the duration of a dot.
     - The length of dot is one unit.
     - Dash contains three dots so it has three units.
     - Space between adjacent dots and dashes is one unit.
     - Space between letters = 3 units
     - Space between words = 5 units
  • The original telegraph machines made a clicking noise as they marked the moving paper tape.
  • The telegraph system spread across America and the world aided by further innovations. Several improvements has been done,in which first was the invention of good insulation for telegraph wires, Another improvement is the quadruplex system, which allowed for four messages to be transmitted simultaneously using the same wire.
  • The use of telegraph system has been increased vastly for sending and receiving information instantly and had a profound economic effect.
  • As the new technologies has been introduced, telegraph usage has been reduced, which has been replaced by telephone, fax machine, internet.
Structure of telegraph

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