History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t4.88

v1.c13.s2.t4.88

D - Maximum diameter (Bosh)# d - Throat diameter# H - Furnace height# 0° - Stack angle# P - Production kg/heat# K - Constant (0.5) for soft ore# V1 - Useful volume# V2 - Volume cm³/kg iron through the bamboo and clay pipes. The bellow (*Bhāthi*) was either made from green bamboo sapling bent to form a circle of about 300 mm diameter or by taking a block of wood and giving it a shape like a trough having 300 mm inner diameter. In case of the bamboo ring two such rings were covered with the leather to give it a shape like a bellow and in the case of the wooden bellow only the top was covered with the leather. There was a hole in the top cover and a leather flap attached to it acting as one way air inlet valve. The bamboo pipe fitted to one side of this bellow was about 500 mm long and had a 12-15 mm diameter hole. The height of the side wall was about 80-100 mm. *Fig.30* shows a photograph of an old pair of bellows. The leather top of the bellow was kept taught with the help of a leather string tied between it and one edge of a green bamboo sapling fixed in the ground at an angle as shown in the figures. The pair of bellows was operated by a single man standing on them and pressing alternately. The operator used two sticks to support himself as shown in some of the figures. Sometimes in order to increase the force two persons stood on the same bellow. The only improvement made in the latter period to increase the size of the bellow and operate it by hand either by sitting by the side of it or with the help of a lever as shown in some of the figures latter in this text, used for melting of steel and non ferrous metals.