1or by a horse or by
water-power; if by a man, the lower board of a large bellows is
fixed to the timbers above the conduit which projects out of the shaft, and so
placed that when the blast is blown through the conduit, its nozzle is
set in the conduit. When it is desired to suck out heavy or pestilential
vapours, the blow-hole of the bellows is fitted all round the mouth of the
conduit. Fixed to the upper bellows board is a lever which couples
with another running downward from a little axle, into which it is
mortised so that it may remain immovable; the iron journals of this little
axle revolve in openings of upright posts; and so when the workman pulls
down the lever the upper board of the bellows is raised, and at the same time
the flap of the blow-hole is dragged open by the force of the wind. If the
nozzle of the bellows is enclosed in the conduit it draws pure air into itself,
but if its blow-hole is fitted all round the mouth of the conduit it exhausts
the heavy and pestilential vapours out of the conduit and thus from the
shaft, even if it is one hundred and twenty feet deep. A stone placed on the
upper board of the bellows depresses it and then the flap of the blow-hole is
fixed to the timbers above the conduit which projects out of the shaft, and so
placed that when the blast is blown through the conduit, its nozzle is
set in the conduit. When it is desired to suck out heavy or pestilential
vapours, the blow-hole of the bellows is fitted all round the mouth of the
conduit. Fixed to the upper bellows board is a lever which couples
with another running downward from a little axle, into which it is
mortised so that it may remain immovable; the iron journals of this little
axle revolve in openings of upright posts; and so when the workman pulls
down the lever the upper board of the bellows is raised, and at the same time
the flap of the blow-hole is dragged open by the force of the wind. If the
nozzle of the bellows is enclosed in the conduit it draws pure air into itself,
but if its blow-hole is fitted all round the mouth of the conduit it exhausts
the heavy and pestilential vapours out of the conduit and thus from the
shaft, even if it is one hundred and twenty feet deep. A stone placed on the
upper board of the bellows depresses it and then the flap of the blow-hole is
A—SMALLER PART OF SHAFT. B—SQUARE CONDUIT. C—BELLOWS.
D—LARGER PART
OF SHAFT.
OF SHAFT.