The traditional view of the development of metallurgy is that only limited temperatures were attainable in early charcoal furnaces, and that smelting ability progressed from lead to iron as furnace temperature capability improved. Present-day combustion technology and reference to published work demonstrates that a simple charcoal furnace 30 centimeters in diameter with a single tuyere easily powered by one man can reach 1600° C, and smelt iron ore to molten cast iron. The production of bloomery iron actually requires a decrease in furnace temperature. The application of the combustion of charcoal to various furnaces and the quantitative analysis of a shaft furnace are reviewed and it is pointed out that early development of metallurgy must have been much more conditioned by the availability of ore deposits than by furnace capability.