Mr. Steel's fire-place was of a circular form, and made to revolve on an upright axis by a gear connected to its lowest extremity; motion was also given, at the same time, to a fluted roller, turning in bearings underneath a hopper filled with coals; this roller broke or crushed the coals to a sufficiently small size, and projected them down an inclined shoot, which distributed them over the circular grate as it turned round, as represented in the annexed section, o o o shows a high pressure tubular boiler, set in masonry; i i is the ring or rim which surrounds the circular grate, made somewhat deeper than the bars, and turning round in an iron trough 3 3, filled with sand, which prevents the air from passing by the rim; N is a metallic plate to receive the ashes which fall," D a toothed wheel, turned by any convenient means in the step at C, and in a cross bar at L above. At F is the receptacle for the fuel; E the breaking and supplying roller, which projects them down the inclined shoot G R, into the revolving grate, which, continually presenting fresh surfaces.

the fuel is pretty uniformly distributed thereon. The grate is made to turn in such a direction that the fresh coals are, immediately after they are deposited, presented to the fire door contiguously situated, where, by the due admission of air, vivid combustion immediately takes place, and the fresh fuel is in bright ignition before more is thrown on the same part, the revolution of the grate being low.