Agricola, Georgius, De re metallica, 1912/1950

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            <p type="caption">
              <s>
                <pb pagenum="181"/>
              is bent down the same distance as it was bent up the last time; the other
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              end of it, which also acts as a journal, is straight. </s>
              <s>This part which protrudes
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              through the wood is protected by two iron washers in the shape of discs, to
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              which are fastened two leather washers of the same shape and size, in order
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              to prevent the water which is drawn into the box from gushing out. </s>
              <s>These
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              discs are around the axle; one of them is inside the box and the other
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              outside. </s>
              <s>Beyond this, the end of the axle is square and has two eyes, in
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              which are fixed two iron rods, and to their ends are weighted lumps of lead,
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              so that the axle may have a greater propensity to revolve; this axle can
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              easily be turned when its end has been mortised in a crank. </s>
              <s>The upper part
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              of the box is the shallower one, and the lower part the deeper, the upper
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              part is bored out once straight down through the middle, the diameter of the
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              opening being the same as the outside diameter of the column pipe; the
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              lower box has, side by side, two apertures also bored straight down;
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              these are for two pipes, the space of whose openings therefore is twice as
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              great as that of the upper part; this lower part of the box is placed
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              upon the two pipes, which are fitted into it at their upper ends, and the
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              lower ends of these pipes penetrate into trunks which stand in the
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              sump. </s>
              <s>These trunks have perforations through which the water flows into
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              them. </s>
              <s>The iron axle is placed in the inside of the box, then the two iron
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              piston-rods which hang from it are let down through the two pipes to the depth
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              of a foot. </s>
              <s>Each piston has a screw at its lower end which holds a thick iron
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              plate, shaped like a disc and full of openings, covered with a leather, and
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              similarly to the other pump it has a round valve in a little box. </s>
              <s>Then the
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              upper part of the box is placed upon the lower one and properly fitted to it on
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              every side, and where they join they are bound by wide thick iron plates, and
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              held with small wide iron wedges, which are driven in and are fastened with
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              clamps. </s>
              <s>The first length of column pipe is fixed into the upper part of the
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              box, and another length of pipe extends it, and a third again extends this one,
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              and so on, another extending on another, until the uppermost one reaches the
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              drain of the tunnel. </s>
              <s>When the crank worker turns the axle, the pistons in
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              turn draw the water through their discs; since this is done quickly, and
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              since the area of openings of the two pipes over which the box is set, is twice
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              as large as the opening of the column pipe which rises from the box, and since
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              the pistons do not lift the water far up, the impetus of the water from the
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              lower pipes forces it to rise and flow out of the column pipe into the drain of
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              the tunnel. </s>
              <s>Since a wooden box frequently cracks open, it is better to
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              make it of lead or copper or brass.</s>
            </p>
            <p type="main">
              <s>The fifth kind of pump is still less simple, for it is composed of two or
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              three pumps whose pistons are raised by a machine turned by men, for each
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              piston-rod has a tappet which is raised, each in succession, by two cams on
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              a barrel; two or four strong men turn it. </s>
              <s>When the pistons descend into
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              the pipes their discs draw the water; when they are raised these force the
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              water out through the pipes. </s>
              <s>The upper part of each of these piston-rods,
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              which is half a foot square, is held in a slot in a cross-beam; the lower part,
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              which drops down into the pipes, is made of another piece of wood and is
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              round. </s>
              <s>Each of these three pumps is composed of two lengths of pipe fixed </s>
            </p>
          </chap>
        </body>
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    </archimedes>
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