106 
Description of a Stove. 
lions part of the fuel is retained longest in pipes in which 
it may undergo a second combustion. 
d. Of tlie heat produced none is of use, but what is 
diffused through the space to be heated, and retained in 
this space. 
5. The temperature in this space will be higher, in 
proportion as the current of air, which is to renew and 
keep up the combustion, is less disposed to absorb the 
heat of this space in passing through it. 
Hence we deduce the following obvious consequences : 
1 . The fire-place must he kept separate from all bodies 
that conduct heat rapidly. 
2. As heat can be produced only by combustion, and 
combustion can be maintained only by a current of air, 
this current should be attracted into pipes, where it pre- 
serves the requisite velocity, without going away from the 
place to he heated ; so that the heat it deposits in it gra- 
dually accumulates -in the whole of the isolated stove, to 
foe afterward given out slowly, according to the laws of its 
equilibrium. 
3. When the wood is consumed to such a point as to 
afford no more smoke, it is of advantage to stop the , out- 
lets of these pipes, to keep in the heat, which would be 
carried into the chimney by the continued, current of 
flesh air, which would necessarily be of a lower tempera- 
ture. 
% We shall obtain a higher temperature, and preserve 
it longer, under similar circumstances, if we construct 
within the stove, or under the hearth and round the fire- 
place, pipes in which the air derived from without, is 
warmed before it enters into the apartment to support the 
fire, or to replace' what has been consumed. 
These pipes are what have been called heat openings, 
fbouches de chaleur,J because instead of considering 
their principal object, it is commonly supposed, that they 
