Agricola, Georgius, De re metallica, 1912/1950

Table of figures

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    <archimedes>
      <text>
        <body>
          <chap>
            <p type="caption">
              <s>
                <pb pagenum="186"/>
              wide and three digits thick. </s>
              <s>The sides of each pump-rod are covered and
                <lb/>
              protected by iron plates, which are held on by iron screws, so that a part
                <lb/>
              which has received damage can be repaired. </s>
              <s>In the “claws” is set a
                <lb/>
              small round axle, a foot and a half long and two palms thick. </s>
              <s>The ends are
                <lb/>
              encircled by iron bands to prevent the iron journals which revolve in the
                <lb/>
              iron bearings of the wood from slipping out of it.
                <emph type="sup"/>
              15
                <emph.end type="sup"/>
              From this little axle
                <lb/>
              the wooden “claws” extend two feet, with a width and thickness of six
                <lb/>
              digits; they are three palms distant from each other, and both the inner and
                <lb/>
              outer sides are covered with iron plates. </s>
              <s>Two rounded iron keys two digits
                <lb/>
              thick are immovably fixed into the claws. </s>
              <s>The one of these keys per­
                <lb/>
              forates the lower end of the first pump-rod, and the upper end of the second
                <lb/>
              pump-rod which is held fast. </s>
              <s>The other key, which is likewise immovable,
                <lb/>
              perforates the iron end of the first piston-rod, which is bent in a curve and
                <lb/>
              is immovable. </s>
              <s>Each such piston-rod is thirteen feet long and three digits
                <lb/>
              thick, and descends into the first pipe of each pump to such depth that its
                <lb/>
              disc nearly reaches the valve-box. </s>
              <s>When it descends into the pipe, the
                <lb/>
              water, penetrating through the openings of the disc, raises the leather, and
                <lb/>
              when the piston-rod is raised the water presses down the leather, and this
                <lb/>
              supports its weight; then the valve closes the box as a door closes an
                <lb/>
              entrance. </s>
              <s>The pipes are joined by two iron bands, one palm wide, one
                <lb/>
              outside the other, but the inner one is sharp all round that it may
                <lb/>
              fit into each pipe and hold them together. </s>
              <s>Although at the present time
                <lb/>
              pipes lack the inner band, still they have nipples by which they are joined
                <lb/>
              together, for the lower end of the upper one holds the upper end of the lower
                <lb/>
              one, each being hewn away for a length of seven digits, the former inside, the
                <lb/>
              latter outside, so that the one can fit into the other. </s>
              <s>When the piston-rod
                <lb/>
              descends into the first pipe, that valve which I have described is closed;
                <lb/>
              when the piston-rod is raised, the valve is opened so that the water can run
                <lb/>
              in through the perforations. </s>
              <s>Each one of such pumps is composed of two
                <lb/>
              lengths of pipe, each of which is twelve feet long, and the inside diameter is
                <lb/>
              seven digits. </s>
              <s>The lower one is placed in the sump of the shaft, or in a tank,
                <lb/>
              and its lower end is blocked by a round piece of wood, above which there are
                <lb/>
              six perforations around the pipe through which the water flows into it. </s>
              <s>The
                <lb/>
              upper part of the upper pipe has a notch one foot deep and a palm wide,
                <lb/>
              through which the water flows away into a tank or trough. </s>
              <s>Each tank is
                <lb/>
              two feet long and one foot wide and deep. </s>
              <s>There is the same number of
                <lb/>
              axles, “claws,” and rods of each kind as there are pumps; if there are three
                <lb/>
              pumps, there are only two tanks, because-the sump of the shaft and the drain
                <lb/>
              of the tunnel take the place of two. </s>
              <s>The following is the way this machine
                <lb/>
              draws water from a shaft. </s>
              <s>The wheel being turned raises the first pump­
                <lb/>
              rod, and the pump-rod raises the first “claw,” and thus also the second
                <lb/>
              pump-rod, and the first piston-rod; then the second pump-rod raises the
                <lb/>
              second “claw,” and thus the third pump-rod and the second piston-rod;
                <lb/>
              then the third pump-rod raises the third “claw” and the third piston-rod, </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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