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THE POPULAR SCIENCE MONTHLY 



"Formerly furnaces were constructed much simpler, and no 

 specific or exact proportions were observed ; and it was not con- 

 sidered necessary that the walls should have any fixed dimen- 

 sions, either as to thickness or height ; but (according to Agricola, 

 who was the first to describe them) the whole structure was rude, 



loose, and imperfect, their daily product of iron was small, and 

 they consumed a very large quantity of charcoal ; but afterward, 

 when it became evident that regularity in smelting insured ex- 

 cellence of product, and at the same time the realization of 



