1sort is made of boards of the same width, but shorter, to which are bound
long thin blades of poplar or some other flexible wood; the third sort has
boards like the last, to which are bound double and triple rows of goose
feathers. This last is less used than the second, which in turn is less used
than the first. The boards of the fan are mortised into the quadrangular
parts of the barrel axle.
long thin blades of poplar or some other flexible wood; the third sort has
boards like the last, to which are bound double and triple rows of goose
feathers. This last is less used than the second, which in turn is less used
than the first. The boards of the fan are mortised into the quadrangular
parts of the barrel axle.
A—FIRST KIND OF FAN. B—SECOND KIND OF FAN. C—THIRD KIND OF
FAN. D—QUADRANGULAR PART OF AXLE. E—ROUND PART OF SAME.
F—CRANK.
FAN. D—QUADRANGULAR PART OF AXLE. E—ROUND PART OF SAME.
F—CRANK.
Blowing machines of the third genus, which are no less varied and of no
fewer forms than those of the second genus, are made with bellows, for by its
blasts the shafts and tunnels are not only furnished with air through conduits
or pipes, but they can also be cleared by suction of their heavy and pestilential
vapours. In the latter case, when the bellows is opened it draws the
vapours from the conduits through its blow-hole and sucks these vapours
into itself; in the former case, when it is compressed, it drives the air through
its nozzle into the conduits or pipes. They are compressed either by a man,
fewer forms than those of the second genus, are made with bellows, for by its
blasts the shafts and tunnels are not only furnished with air through conduits
or pipes, but they can also be cleared by suction of their heavy and pestilential
vapours. In the latter case, when the bellows is opened it draws the
vapours from the conduits through its blow-hole and sucks these vapours
into itself; in the former case, when it is compressed, it drives the air through
its nozzle into the conduits or pipes. They are compressed either by a man,