Vertical Section of a Cylinder Boiler
This is a vertical section of a cylinder boiler. Part A shows the waterway. B is the ashpit inside the cast base of the boiler. C is the firebars. D is the flue. E is the domed top. F is the feeing lid, G is the flower and H is the return pipe sockets.
Nicholson, George The Illustrated Dictionary of Gardening, Div. VI (London, England: L. Upcott Gill, 1884)