Print entitled 'Mast House, Blackwall'. The distinctive masting house built by John Perry beside his Brunswick Dock in about 1790 and demolished in 1862. It was a crane to put masts into ships in the dock, or take them out, a process more usually done by the Navy and elsewhere using a sheer hulk (a form of floating crane, usually on an old ship's hull). This print is from Samuel Owen's series 'The Thames', 1809-11.