Wheatstone's portable ABC telegraph, 1858.

Sir Charles Wheatstone (1802-1875) believed a telegraph system should be simple to operate. In this telegraph receiver, which he patented in 1858, the user cranked a handle continuously while pressing the letter buttons on a large dial. Each time a button was pressed the ABC telegraph sent out electrical impulses, moving a pointer at the far end to the next letter of the message. A smaller dial was used for receiving messages and, during transmission, to check the system was working correctly. Synchronisation was ensured by setting idle instruments to a standard position. This was the first apparatus to print a telegram in type, and could be operated to type at speeds of up to 15 words per minute.