1is broken and part of the chain or
anything else should fall down; he guides
the bag with a wooden shovel, and fills it with water if it fails to take
in the water spontaneously. In these days, they sew an iron band into the
top of each bag that it may constantly remain open, and when lowered into
the sump may fill itself with water, and there is no need for a man to act as
governor of the bags. Further, in these days, of those men who stand on
the floor the one empties the bags, and the other closes the gates of the
reservoir and opens them again, and the same man usually fixes the large
hook in the link of the chain. In this way, three men only are employed in
working this machine; or even—since sometimes the one who empties the
bag presses the brake which is raised against the other drum and thus stops
the wheel—two men take upon themselves the whole labour.
the bag with a wooden shovel, and fills it with water if it fails to take
in the water spontaneously. In these days, they sew an iron band into the
top of each bag that it may constantly remain open, and when lowered into
the sump may fill itself with water, and there is no need for a man to act as
governor of the bags. Further, in these days, of those men who stand on
the floor the one empties the bags, and the other closes the gates of the
reservoir and opens them again, and the same man usually fixes the large
hook in the link of the chain. In this way, three men only are employed in
working this machine; or even—since sometimes the one who empties the
bag presses the brake which is raised against the other drum and thus stops
the wheel—two men take upon themselves the whole labour.
But enough of haulage machines; I will now speak of ventilating
machines. If a shaft is very deep and no tunnel reaches to it, or no drift
from another shaft connects with it, or when a tunnel is of great length and
no shaft reaches to it, then the air does not replenish itself. In such a case it
weighs heavily on the miners, causing them to breathe with difficulty, and
sometimes they are even suffocated, and burning lamps are also extinguished.
There is, therefore, a necessity for machines which the Greeks call
πνευματικάι and the Latins spiritales—though they do not give forth any
sound—which enable the miners to breathe easily and carry on their work.
machines. If a shaft is very deep and no tunnel reaches to it, or no drift
from another shaft connects with it, or when a tunnel is of great length and
no shaft reaches to it, then the air does not replenish itself. In such a case it
weighs heavily on the miners, causing them to breathe with difficulty, and
sometimes they are even suffocated, and burning lamps are also extinguished.
There is, therefore, a necessity for machines which the Greeks call
πνευματικάι and the Latins spiritales—though they do not give forth any
sound—which enable the miners to breathe easily and carry on their work.
These devices are of three genera.
The first receives and diverts into
the shaft the blowing of the wind, and this genus is divided into three species,
of which the first is as follows. Over the shaft—to which no tunnel connects—
are placed three sills a little longer than the shaft, the first over the front,
the second over the middle, and the third over the back of the shaft. Their
ends have openings, through which pegs, sharpened at the bottom, are driven
deeply into the ground so as to hold them immovable, in the same way that
the sills of the windlass are fixed. Each of these sills is mortised into each
of three cross-beams, of which one is at the right side of the shaft, the second
at the left, and the third in the middle. To the second sill and the second
cross-beam—each of which is placed over the middle of the shaft—planks
are fixed which are joined in such a manner that the one which precedes
always fits into the groove of the one which follows. In this way four angles
and the same number of intervening hollows are created, which collect the
winds that blow from all directions. The planks are roofed above with a
cover made in a circular shape, and are open below, in order that the wind may
not be diverted upward and escape, but may be carried downward; and there
by the winds of necessity blow into the shafts through these four openings.
However, there is no need to roof this kind of machine in those localities in
which it can be so placed that the wind can blow down through its topmost
part.
the shaft the blowing of the wind, and this genus is divided into three species,
of which the first is as follows. Over the shaft—to which no tunnel connects—
are placed three sills a little longer than the shaft, the first over the front,
the second over the middle, and the third over the back of the shaft. Their
ends have openings, through which pegs, sharpened at the bottom, are driven
deeply into the ground so as to hold them immovable, in the same way that
the sills of the windlass are fixed. Each of these sills is mortised into each
of three cross-beams, of which one is at the right side of the shaft, the second
at the left, and the third in the middle. To the second sill and the second
cross-beam—each of which is placed over the middle of the shaft—planks
are fixed which are joined in such a manner that the one which precedes
always fits into the groove of the one which follows. In this way four angles
and the same number of intervening hollows are created, which collect the
winds that blow from all directions. The planks are roofed above with a
cover made in a circular shape, and are open below, in order that the wind may
not be diverted upward and escape, but may be carried downward; and there
by the winds of necessity blow into the shafts through these four openings.
However, there is no need to roof this kind of machine in those localities in
which it can be so placed that the wind can blow down through its topmost
part.
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