Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <p type="caption">
              <s>
                <pb pagenum="176"/>
              much water, to drain it by the rag and chain pump or to bring it up in
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              water-bags.</s>
            </p>
            <p type="main">
              <s>Enough, then, of the first sort of pumps. </s>
              <s>I will now explain the other,
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              that is the pump which draws, by means of pistons, water which has been
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              raised by suction. </s>
              <s>Of these there are seven varieties, which though they
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              differ from one another in structure, nevertheless confer the same benefits
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              upon miners, though some to a greater degree than others. </s>
              <s>The first pump
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              is made as follows. </s>
              <s>Over the sump is placed a flooring, through which a
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              pipe—or two lengths of pipe, one of which is joined into the other—are let
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              down to the bottom of the sump; they are fastened with pointed iron clamps
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              driven in straight on both sides, so that the pipes may remain fixed. </s>
              <s>The
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              lower end of the lower pipe is enclosed in a trunk two feet deep; this trunk,
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              hollow like the pipe, stands at the bottom of the sump, but the lower opening
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              of it is blocked with a round piece of wood; the trunk has perforations
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              round about, through which water flows into it. </s>
              <s>If there is one length of
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              pipe, then in the upper part of the trunk which has been hollowed out there is
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              enclosed a box of iron, copper, or brass, one palm deep, but without a bottom,
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              and a rounded valve so tightly closes it that the water, which has been drawn
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              up by suction, cannot run back; but if there are two lengths of pipe, the
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              box is enclosed in the lower pipe at the point of junction. </s>
              <s>An opening or a
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              spout in the upper pipe reaches to the drain of the tunnel. </s>
              <s>Thus the work­
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              man, eager at his labour, standing on the flooring boards, pushes the piston
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              down into the pipe and draws it out again. </s>
              <s>At the top of the piston-rod is a
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              hand-bar and the bottom is fixed in a shoe; this is the name given to the
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              leather covering, which is almost cone-shaped, for it is so stitched that it is
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              tight at the lower end, where it is fixed to the piston-rod which it surrounds,
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              but in the upper end where it draws the water it is wide open. </s>
              <s>Or else an
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              iron disc one digit thick is used, or one of wood six digits thick, each of which
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              is far superior to the shoe. </s>
              <s>The disc is fixed by an iron key which pene­
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              trates through the bottom of the piston-rod, or it is screwed on to the
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              rod; it is round, with its upper part protected by a cover, and has five or
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              six openings, either round or oval, which taken together present a star-like
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              appearance; the disc has the same diameter as the inside of the pipe,
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              so that it can be just drawn up and down in it. </s>
              <s>When the workman draws
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              the piston up, the water which has passed in at the openings of the disc,
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              whose cover is then closed, is raised to the hole or little spout, through which
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              it flows away; then the valve of the box opens, and the water which has
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              passed into the trunk is drawn up by the suction and rises into the pipe;
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              but when the workman pushes down the piston, the valve closes and allows
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              the disc again to draw in the water.</s>
            </p>
            <p type="main">
              <s>The piston of the second pump is more easily moved up and down. </s>
              <s>When
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              this pump is made, two beams are placed over the sump, one near the right side
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              of it, and the other near the left. </s>
              <s>To one beam a pipe is fixed with iron clamps;
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              to the other is fixed either the forked branch of a tree or a timber cut out at
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              the top in the shape of a fork, and through the prongs of the fork a round
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              hole is bored. </s>
              <s>Through a wide round hole in the middle of a sweep passes </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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