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In other countries, furnaces of varying size and structure 
have been devised, but acknowledge the same principle as those 
now used on the burning sands of Africa. 
The invention of bellows, and their eventual application to 
the air bloomery, gave rise to the blast bloomery, and occasioned 
a great revolution and improvement in the fabrication of iron, 
tending materially to increase the pence and to improve the 
quality. 
In time, foot-blasts and hand-blasts, or bellows would be 
abandoned ; oxen would cease to be used, and a more effectual 
moving power, found on the banks of adjacent streams. Water- 
wheels, giving motion to large bellows and hammers, would 
succeed the crude and infantile efforts of a ruder age; so long as 
there was water in the brook, the operation of blowing continued ; 
when this supply ceased, smelting was at an end for the season, 
and the labourers dispersed, some to the mines, others to the 
woods, to prepare materials for another blast. 
A decided advantage was obtained by increasing the size of the 
furnace—it is probable that this enlargement would be pushed to 
the extreme long before any adequate improvement took place in 
the blowing machine. The soft and limited quantity of the blast 
would be found insufficient to penetrate the column of iron-making 
materials after the furnace had been made three or four times the 
height of the old blast bloomery. 
The combustion becoming languid, the furnace was narrowed 
' towards the bottom, in order that the materials might be held in 
partial suspension,—this suspending medium being then and since 
called the ‘‘bosh.” 
The charcoal blast furnace of the present age attained a 
height of thirty feet, the diameter enlarged to eight or nine feet at 
the boshes, and the whole capacity equal in some instances to 
nine hundred or one thousand cubical feet. The first successful 
experiments for making pig iron from coke, were, of course, per- 
formed in the pre-existing charcoal furnace of this size. 
The employment of coke rendered it necessary, in order to 
effect economy in the production of iron, to increase the furnaces 
