The journal starts as a listing of his day's activities, but from 1871 Nov 13 the entries are greatly expanded, sometimes occupying several pages. He records the reasons for failure and his hopes for the future, his experiments to devise a suitable furnace for burning coal dust to produce carbonic oxide gas etc, with frank comments on his colleagues and employees. A list of inventions he has in mind to develop include colour printing, bicycles with spring spokes, a continuous gun, a washing machine, petroleum engine and flying machine.

The journal goes from 1869 Aug 21 to 1879 Apr 13 and contains numerous ink sketches of boilers, furnaces, steam engines etc.