1is bent down the same distance as it was bent up the last
time; the other
end of it, which also acts as a journal, is straight. This part which protrudes
through the wood is protected by two iron washers in the shape of discs, to
which are fastened two leather washers of the same shape and size, in order
to prevent the water which is drawn into the box from gushing out. These
discs are around the axle; one of them is inside the box and the other
outside. Beyond this, the end of the axle is square and has two eyes, in
which are fixed two iron rods, and to their ends are weighted lumps of lead,
so that the axle may have a greater propensity to revolve; this axle can
easily be turned when its end has been mortised in a crank. The upper part
of the box is the shallower one, and the lower part the deeper, the upper
part is bored out once straight down through the middle, the diameter of the
opening being the same as the outside diameter of the column pipe; the
lower box has, side by side, two apertures also bored straight down;
these are for two pipes, the space of whose openings therefore is twice as
great as that of the upper part; this lower part of the box is placed
upon the two pipes, which are fitted into it at their upper ends, and the
lower ends of these pipes penetrate into trunks which stand in the
sump. These trunks have perforations through which the water flows into
them. The iron axle is placed in the inside of the box, then the two iron
piston-rods which hang from it are let down through the two pipes to the depth
of a foot. Each piston has a screw at its lower end which holds a thick iron
plate, shaped like a disc and full of openings, covered with a leather, and
similarly to the other pump it has a round valve in a little box. Then the
upper part of the box is placed upon the lower one and properly fitted to it on
every side, and where they join they are bound by wide thick iron plates, and
held with small wide iron wedges, which are driven in and are fastened with
clamps. The first length of column pipe is fixed into the upper part of the
box, and another length of pipe extends it, and a third again extends this one,
and so on, another extending on another, until the uppermost one reaches the
drain of the tunnel. When the crank worker turns the axle, the pistons in
turn draw the water through their discs; since this is done quickly, and
since the area of openings of the two pipes over which the box is set, is twice
as large as the opening of the column pipe which rises from the box, and since
the pistons do not lift the water far up, the impetus of the water from the
lower pipes forces it to rise and flow out of the column pipe into the drain of
the tunnel. Since a wooden box frequently cracks open, it is better to
make it of lead or copper or brass.
end of it, which also acts as a journal, is straight. This part which protrudes
through the wood is protected by two iron washers in the shape of discs, to
which are fastened two leather washers of the same shape and size, in order
to prevent the water which is drawn into the box from gushing out. These
discs are around the axle; one of them is inside the box and the other
outside. Beyond this, the end of the axle is square and has two eyes, in
which are fixed two iron rods, and to their ends are weighted lumps of lead,
so that the axle may have a greater propensity to revolve; this axle can
easily be turned when its end has been mortised in a crank. The upper part
of the box is the shallower one, and the lower part the deeper, the upper
part is bored out once straight down through the middle, the diameter of the
opening being the same as the outside diameter of the column pipe; the
lower box has, side by side, two apertures also bored straight down;
these are for two pipes, the space of whose openings therefore is twice as
great as that of the upper part; this lower part of the box is placed
upon the two pipes, which are fitted into it at their upper ends, and the
lower ends of these pipes penetrate into trunks which stand in the
sump. These trunks have perforations through which the water flows into
them. The iron axle is placed in the inside of the box, then the two iron
piston-rods which hang from it are let down through the two pipes to the depth
of a foot. Each piston has a screw at its lower end which holds a thick iron
plate, shaped like a disc and full of openings, covered with a leather, and
similarly to the other pump it has a round valve in a little box. Then the
upper part of the box is placed upon the lower one and properly fitted to it on
every side, and where they join they are bound by wide thick iron plates, and
held with small wide iron wedges, which are driven in and are fastened with
clamps. The first length of column pipe is fixed into the upper part of the
box, and another length of pipe extends it, and a third again extends this one,
and so on, another extending on another, until the uppermost one reaches the
drain of the tunnel. When the crank worker turns the axle, the pistons in
turn draw the water through their discs; since this is done quickly, and
since the area of openings of the two pipes over which the box is set, is twice
as large as the opening of the column pipe which rises from the box, and since
the pistons do not lift the water far up, the impetus of the water from the
lower pipes forces it to rise and flow out of the column pipe into the drain of
the tunnel. Since a wooden box frequently cracks open, it is better to
make it of lead or copper or brass.
The fifth kind of pump is still less simple, for it is composed of two or
three pumps whose pistons are raised by a machine turned by men, for each
piston-rod has a tappet which is raised, each in succession, by two cams on
a barrel; two or four strong men turn it. When the pistons descend into
the pipes their discs draw the water; when they are raised these force the
water out through the pipes. The upper part of each of these piston-rods,
which is half a foot square, is held in a slot in a cross-beam; the lower part,
which drops down into the pipes, is made of another piece of wood and is
round. Each of these three pumps is composed of two lengths of pipe fixed
three pumps whose pistons are raised by a machine turned by men, for each
piston-rod has a tappet which is raised, each in succession, by two cams on
a barrel; two or four strong men turn it. When the pistons descend into
the pipes their discs draw the water; when they are raised these force the
water out through the pipes. The upper part of each of these piston-rods,
which is half a foot square, is held in a slot in a cross-beam; the lower part,
which drops down into the pipes, is made of another piece of wood and is
round. Each of these three pumps is composed of two lengths of pipe fixed
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