. De re metallica. Metallurgy; Mineral industries. 208 BOOK VI. or 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
. De re metallica. Metallurgy; Mineral industries. 208 BOOK VI. or 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. A—Smaller part of shaft. B—Square conduit. C- OF shaft. -Bellows. D—Larger part. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Agricola, Georg, 1494-1555; Hoover, Herbert, 1874-1964. New York, Dover Publications
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