The furnace invented by Dr. Davis is made of firebricks and tiles. The outside dimensions are 10 ft. 6 in. long, by 6 ft. 6 in. wide, with 9-in. walls of brick. The furnace rests on a foundation 10 ft. 6 in. by 7 ft. 6 in. and 2 ft. 6 in. deep, of good building stone, with mortar of sharp sand and quicklime or equally suitable material, finished level with the floor of the building. At the rear end the center is occupied by the fire chamber (F) 18 in. wide, 48 in. long, 3 ft. 9 in. high to arch, lined with fire-brick 9 inches thick and roofed with an arched fire-clay tile 4 in. thick, covered by 3-in. shield tile. The iron doors (fire and ash) are furnished with frames, the fire-door is protected by a lining of asbestos and fire-clay; the grate-rest is 1 ft. 3 in. from the floor; beneath the grate are two iron pipes (1½ in.) at the sides, to carry heated air to supply oxygen to the flues (at O); a third iron pipe (⅝ in.) passing to the rear of the fire chamber and up through its back wall to the retort (at P); a fourth pipe (3-in. diameter) leading from the top of the rear end of the retort (at M) down through the rear wall and opening in the ash chamber under the grate-bars (at N), to carry off the surplus gases not consumed in the retort. The air-supply pipes are required to keep up rapid combustion by replacing the oxygen already used, and so to equalize the heat at both ends of the retort. The air-pipes leading into the retort so assists the disintegration of the body in the same way, supplying additional oxygen and making oxidation more rapid. The retort is 9 ft. 9 in. long, 3 ft. wide, and 2 ft. high in the clear; it is floored with 3-in. fire-clay tile in sections; the sides are of 3-in tile, also in sections; the roof is of the same material arched in sections. The retort is made in sections rather than in one single piece, in order to make allowance at the several joints for the great expansion and contraction incident to a heat of 2000 to 2500 degrees, thus avoiding the annoyance and expense of cracks and patching. The retort is supported by the arched roof of the fire chamber and its covering of shield tile, and back of the fire chamber by fire-clay pillars, and at the sides by projections of the tile partitions between the flues. Six pairs of flues surround the retort, 15 and 13½ inches wide respectively, and 3 in. deep, separated by tile partitions 3 in. thick. The gases from the fire chamber enter the first pair through curved openings (QQ) and pass up through AA down through BB (receiving additional oxygen at O), and up again through CC, and through the escape-flue S, into the chimney. The outside facing of the flues is 3-in. tile. Between the outside facing of the flues and the 9-in. brick wall is a space of 3 inches which is packed with asbestos to prevent radiation of heat and allow for lateral expansion and contraction of the outer casing of the flues, giving it much longer life.