descends, and the water barrel again rises. This arrangement is peculiarly advantageous when the furnace has no rear elevation by which to approach the trunnel-head, as is the case at the points mentioned, as well as the furnace of Ex-Governor Porter, situated along side of the railroad, at Harrisburg.

The opposite figure exhibits the interior of a Pennsylvania charcoal furnace of the usual dimensions-width of boshes 94 feet; hearth 5 feet high, two feet in width at bottom, and two and a quarter at the top. Two tons and a half of ore generally produce one ton of metal. For each ton about 180 bushels of charcoal are consumed-varying more or less, according to the quality or kind of wood charred. In charcoal furnaces the fuel, of course, forms one of the leading features. West of the Alleghany, some iron establishments, and a few furnaces, are supplied with coke. To extract the tar, or bituminous matter from the coal, (as also the sulphur, which is injurious in the furnace, and disqualifies the coal for use,) the coals are piled on heaps, or in an oven, and heated to a certain extent, when the atmosphere is shut out by covering

allow the coal to be hauled and thrown in the top with facility. The interior of the ovens is nearly circular, so as to prevent the matter hanging on the walls, as well, also, to facilitate the process of charring. Two or three tons of bituminous coal are placed in the furnace, when the fire is kindled, after which the doors, b b and a, are closed, and the bituminous matter separates from the coal, and leaves behind a spongy substance of about the same quality as charred wood. The process is very little different from that of charring wood, and various

plans are adopted to effect the same object. As there is neither anthracite nor bituminous coal in any of the counties drained by the

wide apart to form a chimney, a. After the wood is thus carefully arranged, brush-wood and loose earth are thrown over the pile, so as to smother the flame, and prevent its bursting out from the mass of wood. The fire is applied to the wood soon after this covering is

effected, which is increased from time to time, as circumstances seem to require. For the purpose of attracting the fire all around the heap, holes are made in the sides to create draft, through which the watery elements of the wood are expelled, by the heat of the hydrogen, oxygen and carbon, which is, in turn, held in check by the exclusion of atmospheric air. Were the air allowed to circulate, the entire mass of wood would be reduced to ashes, The whole process is extremely intricate, depending for complete success on the state of the weather, as well as the skill and watchfulness of the colliers. The burning lasts two or three days and nights, according to the nature of the wood, and the success attending the operation.

The fuel being thus prepared, the next point is in regard to ore. These are of various qualities, and need not be enumerated here. Nearly all ores have to be cleaned, that is, the earthy matter associated with them is removed, either by washing or pounding. After