390I F I R scends and escapes ; beside these, there are double ledges for receiv- ing the lower edges of the other plates. 2. A back plate without holes, that is furnished with a pair of ledges to receive 3. The two side plates, each of which has a similar pair of ledges, for the reception of the side ledges of the front plate, together with a shoulder on which it rests ; there are likewise two pair of ledges for the purpose of admitting the lateral edges of the two middle plates that form the air-box ; and also an ob- long air-hole through which the air warmed in the box is discharged into the room 5 together with a wing or bracket, as at H, and small hole, as at R, in which the axis of the register is to move. 4. An air-box, which is com- posed of the two middle plates D, E, and F, G. D F The first of these two cuts has five thin ledges or partitions, cast on it, the edges of which are .re- ceived into as many pair of ledges, «a*t in the other ; the tops of all FIR the cavities formed by these ledges' are covered by another ledge of the- same form and depth, which is cast with them ; so that when the plates are put together, and the joints luted, there can be no com- munication between the air-box and the smoke. In the. winding passages of this box, fresh air is warmed, as it passes into the room. 5. A front plate, which is arched on the under side, and ornamented with foliage, ike. 6. A top plate, with a pair of ears, M, N, which correspond to those in the bottom plate, and are perforated for the same purpose. It has likewise a pair of ledges that run round the under side, in order to receive the top edges of the fiont, back, and side-plates. The air-box is two and a half inches shorter than the top plate. All these plates are of cast iron ; and, when properly ar- ranged, they are bound with a pair of slender rods of wrought iron, with screws ; and the machine ap- pears as in the preceding figure. There are also two thin plates of wrought iron, forming 7. The shutter ; the length and breadth of which are so propor- tioned, as completely to close the opening of the fire-place ; it also serves to draw the fire, or to secure it during the night. This shutter is
