AMERICAN INDUSTRIES SINCE COLUMBUS. 153 



These are compressed together by certain buttons, placed on the 

 axis of a very large wheel, which is turn'd about by water in the 

 manner of an overshot mill. As soon as these buttons are slid 

 off, the bellows are raised again by the counter-poise of weights, 

 whereby they are made to play alternately, the one giving its 

 blast all the time the other is rising." 



Fig. 3 * is a vertical section of a blast-furnace, such as had 

 been used for some years in Sweden prior to 1734; and it may 

 be regarded as rep- 

 resentative of the 

 construction of fur- 

 nace that had been 

 employed in Ger- 

 many, France, and 

 England for the pre- 

 vious hundred years, 

 and in all probabili- 

 ty for a much longer 

 period. The reader 

 will readily perceive 

 that the bellows 

 (made of wood) were 

 operated by what 

 Henry Powle, above 

 quoted, described as 

 " certain buttons " ; 

 and in fact the con- 

 struction and size 

 of the furnace illus- 

 trated did not differ 

 greatly from that 

 seen by Powle. This 

 Swedish furnace was fifteen feet square outside, and twenty- 

 nine feet high ; its internal diameter at the top, D D, was four 

 feet, and at the widest part six feet. The " boshes," or dimin- 

 ishing part of the furnace, O O, were made of a mixture of fire- 

 clay and crushed quartz ; the inner walls, M M, were of sandstone 

 laid in regular courses, while the outer walls, G G, were made of 

 any convenient coarse, rough stone laid in lime mortar ; the space, 

 F F, between the inner and outer walls, was filled with cinder, 

 small stones, and other similar material. The hearth, C, was about 

 two feet square. The top of the furnace was surmounted by a 

 parapet, H, of rough-hewn logs. Comparing the construction of 

 this furnace with the earlier practice, Swedenborg says : 



Fio. 



3. Vertical Section of a Blast-Furnace of the 

 Seventeenth and Eighteenth Centuries. 



* From De Ferro, by Emanuel Swedenborg, 1734. 



