958 



IRON 



The smelting furnaces have now generally throe tuyeres, and three sets of air- 

 heating furnaces. The figures show two sets built together ; the third set being do- 

 tuched on account of peculiar local circumstances. The air enters the. hoi-ixuiit.il 

 pipe A, iri the ground plan,.%. 1230, on one side of the arched or siphon pipes, shown 

 in upright section \i\fig. 1231, and passes through those pipes to tho horizontal pipe u, 

 on the other side ; whence it proceeds to the blast-furnace. These siphon pipes are 

 flattened laterally, their section being a parallelogram, to give more heating surface, 

 and also more depth of pipe (in the vertical plane), so as to make it stronger, and less 

 liable to bend by its own weight when softened by the rod heat. This system of 

 arched pipe apparatus is set in a kind of oven, from which tho flue is taken out at the 

 top of it; but it thence again descends before it reaches the chimney, entering it 

 nearly at the level of the fire-grate (as with coal-gas retorts). By this contrivance 



1230 



the pipes are kept in a bath of ignited air, and not exposed to tho corroding influence 

 of a current of flame. The places and directions of those oven-flues are plainly marked 

 in the drawing. 



Fig. 1232 is a plan of tho blast-furnace, drawn to a smaller scale than that of tho 

 preceding figures. 



The three sets of hot-blast apparatus all communicate with one line of conducting 

 pipes A, which leads to the furnace. Thus in case of repairs being required in 

 one set, the other two may be kept in full activity, capable of supplying abundance of 

 hot air to the blast, though of a somewhat lower temperature. 



During a visit which Dr. Ure made to Mr. Jessop, at Butterly, he found this emi- 

 nent and very ingenious ironmaster had made several improvements upon his hot- 



