IN this Machine the Smoke first ascends, and then passing over the Iron Plates that compose the warm Air Box, descends to the Bottom, where it passes under a false Back, about three or four Inches from the true Back of the Chimney; then ascends a second time up the Funnel of the Chimney, and passes out at the Top. The Chimney is closed up on all Sides, between the false Back and Breast of the Chimney, except only in one Place, where is an Opening, with an Iron Door, large enough for a Chimney-Sweeper to creep through, to sweep the Funnel; but at all other times this Door is kept shut. There is also a Register fixed in the Smoke-Passage, to give more or less Vent, as shall be required. THE whole is a compleat Piece of Machinery, and was first intended for burning of Wood, which is the common Fuel of that Country; but, for that Reason, is not so well adapted to burn Sea-Coal, whose bituminous Quality would soon close up the narrow Smoke-Passage, and would often require cleaning, and become very troublesome, it being difficult to come at the Smoke-Passage; for if there be a Trap-Door made upon the Hearth, you cannot clean the Smoke-Passage any farther than to the Register, and there is no coming at the upper part without lifting up the Top of the Machine, which is always luted down, and fastened with Screw Nuts. THE Defects and Inconveniences that I have occasionally pointed out, in the Chimneys and Stoves already described, put me upon contriving a new Machine-Grate, which, upon Trial, answers all the Ends that I proposed by it.