382 Application of the Hot Blast in the Manufacture of Cast-Iron. 
The Blowing-engine has a steam-cylinder of 40 inches diameter, and a blowing- 
cylinder of 8 feet deep and 80 inches diameter, and goes 18 strokes a minute. The 
whole power of the engine was exerted in blowing the three furnaces, as well as in 
blowing the four, and in both cases there were two tweers of 3 inches diameter to 
each furnace. The pressure of the blast was 23 lb. to the square inch. The fourth 
furnace was put into operation after the water tweers were introduced, and the open 
spaces round the blowpipes were closed up by luting. The engine then went less 
than 18 strokes a minute, in consequence of the too great resistance of the materials 
contained in the three furnaces to the blast in its passage upwards. 
Materials constituting a Charge. 
Crt. Qrs. Lb. 
1829, Coke, 5 0 0 
Roasted Ironstone, : : 3 J: -_-14 
Limestone, . ; ; : 0 3 16 
1830, Coke, . < A A : 5 0 0 
Roasted Ironstone, - : 5 0 0 
Limestone, . ‘ ; ; 1 1” 16 
1883, Coal, . ‘ d 5 0 0 
Roasted Ironstone, a : 5 0 0 
Limestone, . ; 8 , 1 0 0 
