_Secondly_, THE Streams of cold Air which enters under the Hearth and Back Plates, (where a large Stove-Grate stands) in its various Turnings and Windings, behind these Plates, and through those Tubes, is but very little warmed in its Passage above the Fire in the Conveyances to the Cieling; and it cannot receive any Heat from the Hearth-Plate, unless the Fire was made upon it, as mentioned before; for the bottom Bars of the Stove-Grate are at so great a distance from the Iron Hearth-Plate, that the Fire, with its downward Heat, cannot reach it; and not above Eight superficial Feet of the Back-Plate is warmed by the Fire, and considering the distance from the hot part, to where the warm Air is discharged into the House, nothing is clearer, than that it cannot receive any considerable degree of Heat, in its Passage through the Copper Pipes, that convey it to the Cieling; and where it is suspended, and mixes slowly and imperceptibly with the colder Air in the lower part of the House, so that little or no Warmth can be obtained by this Conveyance. _Thirdly_, FROM hence it appears, that it would have been of much greater Use to have discharged the hot Air immediately from the hot Iron Back-Plate into the Room; its Effects in that Case would have been sensibly felt, and it would then have ascended naturally, without the help of Pipes, and warmed the circumambient Air as was intended; and likewise would have supported the Fire, without the Assistance of any Air from the Doors and Crevices. FIFTHLY, Stoves, placed at the End of long Rooms, Coffee-Houses, and Tradesmen’s Shops, warm the Room in a little Time; but the Smoke and upright Heat are both conveyed thro’ one and the same Tube of Iron, jointed in several Pieces, to bring them round the Wall and Turnings of the Chimney, where they are discharged: but never fail to send out some part of the Air impregnated with Sulphur, so as to occasion a disagreeable Smell, and often, Head-achs and Lowness of Spirits to those that are not accustomed to these Stoves.