212 The Description of a Safety Furnace. 
with a lambent flame sufficient to ignite explosive mixtures of 
gas. 
A fire which will burn with perfect safety in mines, and at the 
same time occasion a brisk circulation of air, has been hitherto 
a desideratum. I am induced to believe, that I have discovered 
how this may be obtained by the introduction of a furnace, sim- 
ple in construction, in which coke or even common coal may be 
burnt, without any danger, and the circulation of air in the mine 
greatly increased. 
The furnace or stove admits of considerable variation in size 
and form, according to the situations in which it may be used; 
and as it can be erected at a small expense, I trust no prejudice can 
exist to prevent a fair trial ofits utility. The accompanying draw- 
ing will explain its construction, and enable any coal proprietor to 
apply the furnace to his own use. AAaa (Plate III. fig. 1,) re- 
present the body of the stove and chimney, which should be of cast 
iron in one piece without any side-door or opening whatever, as 
it is supplied with fuel at the mouth or chimney, J/ represent 
the grate, which moves upon an hinge, and opens downwards by 
removing an iron peg c, in order to clear the grate when wanted, 
and dd a broad rim below the grate perforated by the air-holes 
eee. F is a cistern of stone or brick to be filled with water 
above the lower edge of the rim dd. The diameter of the fur- 
nace at the grate may be 30 inches, that of the chimney about 
18 inches, to admit the fuel. The height of the chimney, if 
coke be used, need scarcely exceed ten feet, and may be inclined 
or not at option, according to the situation. When the furnace 
is lighted, which may be done by introducing lighted coke down 
the chimney, there will be no access of air but through the aper- 
tures eee, which may be regulated at pleasure, by stops to in- 
crease or diminish the current. The use of the water-trough is 
to confine the admission of air to the openings ee, and also to 
prevent any accidental inflammation of coal or other substance 
below the grate. 
Sheuld the air, of the mine be charged with inflammable gas 
to the explosive point, it is prevented from passing near the sur- 
faee of the fire by the sides of the stove; and should even the 
lowest stratum of air which enters the apertures ee be explosive, 
which can rarely occur, this air will lose a part of its oxygen 
by passing through the red-hot coke, and by its further admix- 
ture with carbonic acid gas confined in the stove, must cease to 
be inflammable. ‘The general current of inflammable air will 
pass with perfect safety over the mouth of the chimney, and will 
ascend the shaft from the heat communicated to it by the sur- 
face of the stove. If common coal be used, a chimney of greater 
length 
oe 
