 CB27) on the mineral deposits, workings, buildings and drainage at collieries across Scotland.One of Bald's earliest publications was "A General View of the Coal Trade in Scotland" (1808), which is considered "an excellent technical account of coal mining during the Industrial Revolution", the book was reprinted in 1812 with the addition of "An Inquiry into the Conditions of Women who carry Coals under Ground in Scotland, known by the name of Bearers", in which he denounced this labour as a form of slavery.In 1812 David Brewster commissioned Bald to write the 'mine' entry for the 'Edinburg Encyclopaedia', a task that involved visiting the colliery at Killingworth where George Stephenson had introduced a steam-powered machine for raising coal from the pit face.