COWPER STOVE. In blast furnace practice it is eco nomical to heat the air supplied to the furnace. This is effected by causing the furnace to heat its own supply of air, as is now always done save in the case of cold blast furnaces employed to produce certain qualities of iron. The first economical appliance invented to heat the blast was the invention of E. A. Cowper in 186o; hence the name "Cowper stove." The Cowper stove consists of a large vertical steel shell, con taining a combination chamber and a number of narrow vertical flues, built in brickwork, which are heated by the waste furnace gas. When sufficient heat has been absorbed through the flues, the fuel gas is shut off and the air for the blast heated by being driven through the hot flues on its path to the furnace. So the operation proceeds, the Cowper stove being alternately "on gas" and "on wind," first heated, and then cooling as it imparts heat to the blast. (See IRON AND STEEL.)