The smelting-furnace is a cone, not more than four feet high, widening at the top into a great goblet shape. So little deviation was there in the form of any that I saw that all seemed to me to be erected on precisely the same model. One obstacle to the construction of larger furnaces is the extreme difficulty of preventing the mass of clay from cracking in the process of drying. The cup-shaped aperture at the top communicates by a very small throat with the cavity below, which is entirely filled with carbons. Into the upper receiver are thrown fragments of ore, of about a solid inch, till it is full. The hollow tunnel extends lower than the level of the ground; and the melted mass of iron, finding its way through the red-hot fuel, collects below in a pile of slag. At the base there are four openings: one of these is much larger than the others, and is used for the removal of the scoriæ; the other three are to admit the long tewel-irons, which reach to the middle of the bottom, and keep the apertures free for the admission of air. Without stoking, the openings would very soon become blocked up with slag. In reply to my inquiry I was told that bellows are never employed; it was said that too fierce a fire was injurious, and caused a loss of metal. A period of a day and a half, or about forty hours, is requisite to secure the product of one kindling. When the flames have penetrated right through the mass of ore until they rise above it, the burning is presumed to be satisfactory. Amongst the Bongo the furnaces are different, being generally constructed in three compartments, and fitted with bellows. They also place layers of ore and fuel alternately. The deposit of metal and fuel is heated a second time, and the heavy portion, which is detached in little leaflets and granules, is once more subjected to fire in crucibles of clay. The particles, red-hot, are beaten together by a great stone into one compact mass, and, by repeated hammering, are made to throw off their final dross. Nearly half of the true metal is scattered about during the progress of the smelting, and would be entirely lost if it were not secured by the natives. In regard to its homogeneousness and its malleability, the iron procured in this way is quite equal to the best forged iron of our country.