History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c12.s1.t3.9

v1.c12.s1.t3.9

For smelting ore the furnaces were built locally. The furnace was cemented with clay and the nozzles of the bellows were built up in it. The nozzles were earthen tubes which were thickest at the furnace end and at the top of the thick part there was a small air hole usually closed with a piece of wet rag but opened now and then to clear the tubes. The other end of the tube was fixed to the bellow. The bellow valve was formed by two sticks at the mouth, which were opened when the bag was raised for the admission of the air and closed when the bellows were pressed down. The upper part of the furnace was built with rings of fire-clay about 10 inch (25.4 cm) deep. The bellows were worked on three sides whilst the fourth side was the opening to the furnace, in which a plate of fireclay was placed, at the lower part of which was a hole for stirring the molten metal and to allow it to flow out.