Mr, George Thomson on Blast Furnaces. 



and 6 feet high upon the top, as represented in 



Simple as the alteration appears, however, 

 it was followed bj very extraordinary results ; 

 the moment the charge arrived at the bottom, 

 the iron, from hard forge, became fine No. 1. 

 The burden was accordingly increased from 

 time to time, until this furnace, with the same 

 material and same blast, made GO tons per 

 week of good forgo pigs, with a consumption of 

 only SI tons of coal to a ton of iron. The result is 

 not attributable to the widening and double-fill- 

 ing holes alone; for the effect was repeatedly tried 

 by filling-holes at the original height directly 

 under the upper ones, and in every case we had to 

 ^ / take burden off to make an equal quality, there- 



fr j—M 1^^ reducing both the quantity and the yield. 



Mr. Gibbons, of Corbyns Hall furnaces, 

 near Dudley, has arrived at very striking 

 results with cold blast, by alteration of shape and increase of size. 

 He states in his publication on the subject, that he was led to the 

 idea by observing the well-known fact, that furnaces, especially cold 

 blast ones, scarcely ever come into full work until six months after 

 they have been blown in ; and also, that every year, so long as the 

 "boshing" of the furnace is not wholly gone, they improve their work 

 both in yield and in quantity ; further, in observing that furnaces, when 

 PiQ^ 3^ blown out, although they had not been working 



.4^.1 _^ for more than six or eight months, were ma- 

 terially altered from their original shape. 

 By studying the natural shape, as it might 

 be termed, he has arrived at an improved 

 form, as at fig. 4. 



This improved furnace (fig. 4,) has more 



than double the capacity of his original one, 



(fig. 3,) and the larger content is in the upper 



half — the top is 8 feet diameter, and there are 



four filling-holes. The greatest produce of his 



original furnace he states to have been 74 



^ tons per week, while that of the improved one 



5|i has reached 115 tons in one week. This is by 



^ cold blast, with a density of only 1 lb. 13 oz. 



per inch at the twere. 



Mr. Gibbons' opinion, like that of many 

 others, is, that with the hot blast, the shape 

 or the size has very little effect ; but that this 

 is not the case is now well known. 



