One of the chief inconveniences attending the use of air-heating furnaces arises from the fact that in the combustion of the fuel, particles of solid carbon get taken up by the draft, and these, lodging in the draft passages and radiator, gradually accumulate, and fill up the passages, thus preventing the perfect operation of the furnace. The invention we are about to describe is designed to obviate this difficulty by arranging the radiators and dampers of the furnace in such a way that the dampers may be made to perform the double function of dampers and scrapers, and thereby keep the radiators perfectly clean, with great facility. Our engraving is a vertical central section of a furnace, showing this improvement. A is the body of the furnace, and B is a cylindrical radiator or drum that is placed above it, and communicates with it by flues, C D. The flue, C, is cylindrical, but the flue, D, has two parallel sides, with semi-circular ends—a transverse section forming an oblong. E is an air-heating chamber, which is of circular form, and is fitted horizontally within the radiator, B. This air chamber is quite shallow, and communicates with the external air by means of passages, a, the orifices of which project through the side of the radiator, B. A passage, b, is made through the chamber, E, in line and corresponding in form with the flue, D, and F is a smoke pipe, communicating with the upper part of the radiator, B. G is an arbor, which passesvertically through B and E, and it can turn freely within them. On this arbor, G, two dampers, H I, are placed directly over one another, and in the same plane; they are formed of flat metal plates, rather larger than the flue, D, both being constructed exactly alike, and having a flanch, a', on each of them. The damper, H, is placed directly over the bottom plate, c, of B, and the damper, I, is placed immediately over the top plate, d, of the air heater, E. To the upper end of the arbor, G, a wheel, J, is attached, and one end of a rod, K, is pivoted to one side of it, the other end of the rod being pivoted to a crank on a rod, f, which also forms the joint rod of the door, L. The operation is as follows :—The products of combustion pass up through the flue, C, through the radiator, B, and through the passage, b, that is made through the air-heater, E, and up between the inner edge of E, and the sides of B, (E being of somewhat less diameter than B,) and into the smoke pipe, F. The damper, H, works directly over the orifice of D, and the damper, I, works over the orifice, b, and it will be seen that as the door, L, is opened or closed the dampers, H I, will move over the orifices of the flue and passage, keeping them free from soot or dirt, the dampers closing D and b when the door is closed, and moved off them, or leaving them open, when the door is open, to prevent smoke or gas escaping into the air. By detaching the rod, K, from the rod, f, the dampers, H I, may be turned completely around, so that all the soot and dirt may be loosened, and passed down the flues, C D, into the fire. This invention saves much labor, for it is extremely difficult to clean many forms of radiators, it being impossible to render their interiors very accessible ; but by having the dampers arranged so as to operate as above described, the radiator can be kept perfectly clean. The inventor is T. Dwight Ingersoll, of Monroe, Mich., and a patent was granted to him March 30, 1858. By addressing him as above any further particulars can be obtained.