Dated 1840-1850. From Scientific apparatus, musical instruments and telegraph equipment, [1834-1875].

ABC transmitting telegraphs designed by Wheatstone using a step by step mechanism.   The dial is rotated to the required character which operates ‘make and break’ contacts beneath the dial sending current impulses down the line to the receiver.  [See K/PP107/1/4/42].  Brass dial mechanism with 30 arms each marked with letters and numbers radiating from a brass plate attached to a mahogany base.