12 
Steam JLngine. 
G. A brick placed with its whole length across the fijre- 
place, to hinder the coals from falling down the space F, 
and choking it. 
Fig. 2, is a front view of the same boiler, and fire-place ; 
in which the same letters represent the same parts. 
HH are two slides, the one shifting backwards the 
other forwards, to make the space F, for the current of air, 
larger or smaller, as, by practice, may be found best. 
Manner in which this Furnace operates. 
The arch C hinders the smoke from going up the chim- 
ney, and obliges it to pass through the fire behind it ; 
which has a very strong draught, and burns the smoke 
as it passes through it. The air which comes up through 
the space F gives fresh vigour to the flame, which con- 
sumes any smoke that may be left* 
It must be observed that too much air will have a very 
bad effect, as it will cool the flame : therefore the slides 
H H must be regulated in such manner as the operator 
may find most advantageous. 
The shutter in the door E must also be of a proper size \ 
as its being too large or too small will be prejudicial. 
I am, &c. 
W. Thomson. 
Method of consuming smoke by James and John RobertsoUy 
of Tradestown^ near Glasgow^ Engineers. Patented 
August 13, 1800. Rep. Arts. A. S. No. 96, 
Specification and description of the nature of a new 
and improved method of constructing furnaces, for the 
application of fire to steam-engines and boilers of various 
descriptions, and also the application of fire to many other 
purposes and branches of manufacture where heat is ap- 
plied by means of a furnace, by which invention and im- 
