1prone to motion as it revolves.
And so, when the workman turns the axle
by the crank, the fans, the description of which I will give a little later, draw
in the air by the blow-hole, and force it through the other blow-hole which
leads to the conduit, and through this conduit the air penetrates into the
shaft.
by the crank, the fans, the description of which I will give a little later, draw
in the air by the blow-hole, and force it through the other blow-hole which
leads to the conduit, and through this conduit the air penetrates into the
shaft.
The one with the box-shaped casing is furnished with just the same
things as the drum, but the drum is far superior to the box: for the fans so
fill the drum that they almost touch it on every side, and drive into the
conduit all the air that has been accumulated; but they cannot thus fill
the box-shaped casing, on account of its angles, into which the air partly
retreats; therefore it cannot be as useful as the drum. The kind with a
box-shaped casing is not only placed on the ground, but is also set up on timbers
like a windmill, and its axle, in place of a crank, has four sails outside,
like the sails of a windmill. When these are struck by the wind they turn
the axle, and in this way its fans—which are placed within the casing—drive
118[Figure 118]
things as the drum, but the drum is far superior to the box: for the fans so
fill the drum that they almost touch it on every side, and drive into the
conduit all the air that has been accumulated; but they cannot thus fill
the box-shaped casing, on account of its angles, into which the air partly
retreats; therefore it cannot be as useful as the drum. The kind with a
box-shaped casing is not only placed on the ground, but is also set up on timbers
like a windmill, and its axle, in place of a crank, has four sails outside,
like the sails of a windmill. When these are struck by the wind they turn
the axle, and in this way its fans—which are placed within the casing—drive