Black Line print coloured of general arrangement of pumping engine at Philadelphia Pit

Black Line print coloured of general arrangement of pumping engine at Philadelphia Pit, Gildersome near Leeds, framed.

This beam engine, which dates from the early part of the 19th century, was used until 1912 for pumping floodwater at the Philadelphia Pit, Gildersome, near Leeds. It resembles in construction Watt's single-acting engine, where steam was only admitted above the piston, except that the cylinder is open-topped and in consequence the piston acts by atmospheric pressure only. This permits some simplification in the valve gear, since Watt's equilibrium valve (which passed exhaust steam from above the piston to beaneath it and then to the condenser) is dispensed with, but at the cost of increased steam consumption.