King's College London
Exhibitions & Conferences
Professor Sir Charles Wheatstone

The ABC telegraph

Alphabetic dial of ABC TelegraphAlphabetic dial of ABC TelegraphThe ABC telegraph or ‘Communicator’ as it became known, was patented by Charles Wheatstone and William Fothergill Cooke in 1840 and was the first commercial ‘dial telegraph’.

The dial was inscribed with the letters of the alphabet displayed like a clock hand and at the front was a hand-operated generator, a dial with 30 keys around the edge and a pointer.

The operation of the telegraph was relatively simple:

  • The relevant alphabetic key was pressed and the generator wound.
  • The pointer would go round until it reached the alphabetic key pressed and then the generator was disconnected.
  • Pressing another key then allowed the pointer to rotate to the next letter and so on.
  • Another dial on the machine would show letters of the message being sent to the receiver.

ABC Telegraph - The 'Communicator'ABC Telegraph - The 'Communicator'The ABC telegraph removed the need for a highly trained operator and could transmit up to fifteen words per minute.

Wheatstone continued to develop the design and in 1858 he patented an advanced model of the ABC Telegraph.

Owing to its ease of operation, the advanced model was favoured for private telegraphic communication both in households that were able to afford such a device and by the Post Office for their telegram services.

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