This invention, which we have seen repeatedly and successfully applied, forms a distinct appendage to the front of the furnace. At the upper part of the apparatus is a hopper, containing a supply of small coals adequate to an hour or two's consumption. Through an aperture at the lower extremity of this vessel, the coals drop between two grooved rollers, which revolve in opposite directions, and break those which are too large to pass without reduction between them; they then fall upon a flat plate of iron, whence they are continually projected by the arms of a kind of revolving fanner, which scatters them evenly over the burning fuel on the grate, where it lies in a thin bed, in order that the air may pass upward through them the more easily. The apparatus is, however, usually adjusted to throw a larger proportion of the fuel near the fire bridge, so that it may lie there heaped up or in a thicker stratum, in order that the small quantity f smoke arising from the fresh fuel in front may be consumed in passing over the bridge.