APPENDIX 38 
N° Ill. 
[T is faid the northern Chinefe have a method of warm- 
ing their. ground floors, which is ingenious. Thofe 
floors are made of tile a foot {quare and two inches thick, 
their corners being fupported by bricks fet on end, that 
are a foot long and four inches fquare, the tiles, too, join 
into each other, by ridges and hollows along their fides. 
This forms a hollow under the whole floor, which on one 
fide of the houfe has an opening into the air, where a fire 
is made, and it has a funnel rifling from the other fide to 
carry off the fmoke. The fuel is a fulphurous pitcoal, 
the {mell of which in the room is thus avoided, while the 
floor and of courfe the room is well warmed. But as the 
underfide of the floor muf grow foul with foot, and a thick 
coat of foot prevents much of the direct application of the 
hot air to the tiles, I conceive that burning the fmoke by 
obliging it to defcend through red coals, would in this 
con{truction be very advantageous, as more heat would be 
given by the flame than by the {moke, and the floor be- 
ing thereby kept free from foot would be more heated 
with lefs fire. For this purpofe I would propofe erecting 
the funnel clofe to the grate, fo as to have only an iron 
plate between the fire and the funnel, through which plate 
the air in the funnel being heated, it will be fure to draw 
well, and force the {moke to defcend, as in the figure. 
Fiewe'g. Where A is the funnel or chimney, B the grate on 
? which the fire is placed, C one of the apertures 
through which the defcending fmoke is drawn into the chan+ 
nel D of figure 10, along which channel it is conveyed by a 
circuitous rout, as defignated by the arrows, until it ar- 
rives at the {mall aperture E, figure 10, through which it 
enters the funnel F. G in both figures is the iron plate 
againft which the fire is made, which being heated there- 
by, will rarefy the air in that part of the funnel, and caufe 
the {moke to afcend rapidly. The flame thus dividing 
E from 
