Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <p type="caption">
              <s>
                <pb pagenum="190"/>
              of a palm, that it may be able to take the end of the pipe which
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              follows. </s>
              <s>And each length of pipe is fixed with iron clamps to the timbers of
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              the shaft, that it may remain stationary. </s>
              <s>Through this continuous series
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              of pipes, the water is drawn by the balls of the chain up out of the sump as
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              far as the tunnel, where it flows out into the drains through an aperture in
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              the highest pipe. </s>
              <s>The balls which lift the water are connected by the iron
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              links of the chain, and are six feet distant from one another; they are made
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              of the hair of a horse's tail sewn into a covering to prevent it from being
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              pulled out by the iron clamps on the drum; the balls are of such size that
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              one can be held in each hand. </s>
              <s>If this machine is set up on the surface of
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              the earth, the stream which turns the water-wheel is led away through open­
                <lb/>
              air ditches; if in a tunnel, the water is led away through the subterranean
                <lb/>
              drains. </s>
              <s>The buckets of the water-wheel, when struck by the impact of the
                <lb/>
              stream, move forward and turn the wheel, together with the drum, whereby
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              the chain is wound up and the balls expel the water through the pipes. </s>
              <s>If
                <lb/>
              the wheel of this machine is twenty-four feet in diameter, it draws water from a
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              shaft two hundred and ten feet deep; if thirty feet in diameter, it will draw
                <lb/>
              water from a shaft two hundred and forty feet deep. </s>
              <s>But such work requires
                <lb/>
              a stream with greater water-power.</s>
            </p>
            <p type="main">
              <s>The next pump has two drums, two rows of pipes and two drawing­
                <lb/>
              chains whose balls lift out the water; otherwise they are like the last pump.
                <lb/>
              </s>
              <s>This pump is usually built when an excessive amount of water flows into the
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              sump. </s>
              <s>These two pumps are turned by water-power; indeed, water draws
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              water.</s>
            </p>
            <p type="main">
              <s>The following is the way of indicating the increase or decrease of the
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              water in an underground sump, whether it is pumped by this rag and chain
                <lb/>
              pump or by the first pump, or the third, or some other. </s>
              <s>From a beam which
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              is as high above the shaft as the sump is deep, is hung a cord, to one
                <lb/>
              end of which there is fastened a stone, the other end being attached to a
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              plank. </s>
              <s>The plank is lowered down by an iron wire fastened to the
                <lb/>
              other end; when the stone is at the mouth of the shaft the plank
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              is right down the shaft in the sump, in which water it floats. </s>
              <s>This
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              plank is so heavy that it can drag down the wire and its iron clasp and
                <lb/>
              hook, together with the cord, and thus pull the stone upwards. </s>
              <s>Thus, as
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              the water decreases, the plank decends and the stone is raised; on the
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              contrary, when the water increases the plank rises and the stone is lowered.
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              </s>
              <s>When the stone nearly touches the beam, since this indicates that the water
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              has been exhausted from the sump by the pump, the overseer in charge of the
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              machine closes the water-race and stops the water-wheel: when the stone
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              nearly touches the ground at the side of the shaft, this indicates that the
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              sump is full of water which has again collected in it, because the water raises
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              the plank and thus the stone drags back both the rope and the iron wire;
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              then the overseer opens the water-race, whereupon the water of the stream
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              again strikes the buckets of the water-wheel and turns the pump. </s>
              <s>As
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              workmen generally cease from their labours on the yearly holidays, and </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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