Assay laboratory with various forms of furnace including and athanor or 'Slow Harry', 7, self-stoking furnace for cementation, 9, and barrel-shaped furnace, 3, in which draught supplied by steam from water in container placed over hot charcoals. At 4 a crucible is being gradually heated in a ring of burning coals: to increase the heat coals could be raked into a smaller circle. From 1683 English edition of Lazarus Ercker Beschreibung allerfurnemisten mineralischen Ertzt- und Berckwercksarten originally published in Prague in 1574. Copperplate engraving.