Unsatisfactory operation of George Stephenson stationary engines on the Etherley And Brusselton Incline, the need to make a change, Stephenson begged Timothy Hackworth to put it off until summer as it would ruin his character, suggests changes, George Stephenson would take 'umbrage' if he knew of the correspondence, he does not 'readily forgive', has spoken to Mr Storey about the matter. Referenced in Robert Young, Timothy Hackworth and the Locomotive (London: Locomotive Publishing Company, 1923), p. 129 and 130.