THE Construction of the Second Sort consists of a Grate of a particular Make, with a Box of Plate-Iron behind the Back, that has only three Cavities; one End communicates with the outward Air to bring it through those Cavities, obliquely, to the Corner in the Brick-Work; from thence it is brought forward in the upper part of the Jamb, quite into the Tin Canal, behind the Mantle-Piece, as in the last Construction; but the same Inconvenience attends both these sort of Chimnies, that the upright Heat, which is at least three-fourths of what proceeds from the Fire, is almost wholly lost; as it is in all the open Fire-Places. THIRDLY, the _Dutch_ and _German_ Stoves, which are very different. THE _Dutch_ Stove has a Flue proceeding from the Top, which is sometimes bent downwards, and then goes into the Chimney, through a false Back, at about four Inches from the true Back: That Space has a Communication with the Funnel, and all the other Parts of the Chimney are wholly closed up. AND there are others which have the Flue straight upward, that goes into the Chimney, and all the Funnel closed up round the Flue of the Stove. The First Sort, in my Opinion, is the best; for there is not so much of the upright Heat lost as in this, and the Chimney cannot so readily smoke; because the Space between the false Back and the true Back obstruct, in some degree, the Passage of the Air down the Chimney. Both these sorts have a small Iron Door into the Room, which in some degree changes the Air as it flows to that Opening; part of which goes off with the Smoke, and its Place is supplied by the entering Air from Doors, Windows, and Crevices. But as there is so small a Change of Air, the Room will soon be warm, the Chimney being wholly closed up; very little Air is required to supply the small Door of the Stove, and that only can enter at the Door or Windows of the Room: Little Fuel serves, for almost all the Heat is saved. This small change of Air makes these Stoves wholesomer, or at least pleasanter, than the _German_ Stoves, but there is little sight of the Fire; and no other Use can be made of it but to warm the Room: And if any ill Smell should happen in the Room, it is not easily carried off, by Reason of the slow change of Air at the little Iron Door; and the Room is always somewhat suffocating, especially to those who are not accustomed to it.