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(so to speak) Air through the Tube, without which it cannot burn, which yet it will do, as is obvious to conceive, (all Illustrations, and Philosophical Explications being here superfluous,) and so, while the Air is drawn by the fire from the farthest or most inward part of the Mine or Adit, fresh Air must needs come in from without, to supply the place of the other, which by its motion doth carry away with it all the vapors, that breath out of the ground; by which means the whole Adit will be alwaies filled with fresh Air, so that men will there breath as surely as abroad, and not only Candles burn, but Fire, when upon occasion there is use for it for breaking of the Rock.
Now that there may be no want of such fresh Air, the Fire must alwaies be kept burning in the Chimney, or at least as frequently as is necessary: For which purpose there must be two of the Iron Grates or Chimneys, that when any accident befals the one, the other may be ready to be in its place, the Coals being first well kindled in it; but when the fire is neer spent, the Chimney or Grate being haled up to the dore, is to be supplied with fresh fuel.
The Figure of the Fabrick, Chimney, and all the parts thereof being hereunto annexed, the rest will be easily understood.
Figure 1.
A. The Hole for taking out the Ashes.
B. The Square-hole, into which the Tube or Pipe for conveying the Air is to be fixed.
C. The Border or Ledge of Brick or Iron, upon which the Iron-grate or Cradle, that holds the burning Coles, is to rest, the one being exactly fitted for the other.
D. The Hole where the Cradle is set.
E. The woodden Tube, through which the Air is conveyed towards the Cradle.
F. The Dore, by which the Grate and Cradle is let in, which is
