Dated 1843-1872. From Working papers, experimental notes and correspondence relating to the development of the electric telegraph, [1836-1960].

Experimental notes compiled by Charles Wheatstone in particular detailing early practical experiments in telegraph relay over long distances, including an experiment conducted at Ascot racetrack, Berkshire, 1844; transcriptions of telegraph messages sent by the Police, 1844; correspondence concerning payment for the supply of electric telegraph instrumentation, 1844; correspondence between Wheatstone, Cromwell Fleetwood Varley (1828-1883), telegraph engineer, and Josiah Latimer Clark (1822-1898), electrical engineer, on the measurement of electrical potential, 1865; description of the difference of opinion between Wheatstone and (Josiah) Latimer Clark on the velocity of electrical transmission, with note on a patent application lodged by Clark, 1866; papers concerning differential induction, specific induction and the electrometer, 1860-1870; observations on electrical conductivity of deposits of copper in Cornish mines; working notes on electromagnets and batteries in relation to electric telegraphs, including diagrams and sketches, with test results; notes entitled 'another method of measuring resistance'; heads of reflections on Ohm's Law and its application to the electric telegraph.