Cooke and Wheatstone's first telecommunication device, 1837.

Line drawing with colour wash by John Farey, of William Fothergill Cook's (1806-1879) and Charles Wheatstone's (1802-1875) first English specification of 12 December 1837, for 'Improvements in giving signals and sounding alarums in distant places by the means of electric currents transmitted through metallic circuits'. (Patent for England 12 June 1837).