THE CONQUEST OF NATURE 



sible down the elevator shaft into the pure atmosphere 

 below. It was not an uncommon thing in the neigh- 

 borhood of these older furnaces to see stretched about on 

 the ground at the base several workmen in various stages 

 of suffocation. Fortunately, by use of precautionary 

 measures, fatal accidents were rather unusual, the men 

 being overcome only temporarily, and usually recov- 

 ering quickly and returning to work. 



But the poisonous gas coming from the top of the 

 furnace was not the only, nor the worst, danger con- 

 stantly menacing the men on the staging. Their 

 greatest dread was the possibility of explosions occurring 

 in the furnace, which might hurl the bell into the air 

 and deluge the upper structure with molten metal. 

 Against this possibility there was no safeguard in the 

 older furnaces, explosions occurring without warning 

 and frequently with terrible effects. But fortunately 

 these older types of furnaces are being rapidly replaced 

 by the newer forms in which the danger to life, at least 

 from gas and explosions, is minimized. And even in 

 the older furnaces, improvements in the structure of 

 the bell and in methods of filling have greatly lessened 

 the dangers. 



In the modern type of blast-furnace the work at the 

 top formerly performed by men on the staging is ac- 

 complished entirely by machinery. The general appear- 

 ance of these furnaces is that of huge iron pipes or 

 kettles mounted on several iron legs. The outer struc- 

 ture, or shaft, is constructed of plate iron, but this 

 is lined with fire brick of considerable thickness, and 

 may have a water jacket interposed between these 



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