Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
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          <chap>
            <p type="caption">
              <s>
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              method of grinding requires the millstone to be now raised and now
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              lowered, the timber in whose socket the iron of the pinion axle revolves, rests
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              upon two beams, which can be raised and lowered.</s>
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            <p type="main">
              <s>There are three mills in use in milling gold ores, especially for quartz
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              11
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              which is not lacking in metal. </s>
              <s>They are not all turned by water-power,
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              but some by the strength of men, and two of them even by the power
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              of beasts of burden. </s>
              <s>The first revolving one differs from the next only
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              in its driving wheel, which is closed in and turned by men treading it, or by
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              horses, which are placed inside, or by asses, or even by strong goats; the
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              eyes of these beasts are covered by linen bands. </s>
              <s>The second mill, both
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              when pushed and turned round, differs from the two above by having an
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              upright axle in the place of the horizontal one; this axle has at its lower end
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              a disc, which two workmen turn by treading back its cleats with their feet,
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              though frequently one man sustains all the labour; or sometimes there
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              projects from the axle a pole which is turned by a horse or an ass, for which
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              reason it is called an
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              asinaria.
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              </s>
              <s> The toothed drum which is at the upper end
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              of the axle turns the drum which is made of rundles, and together with it the
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              millstone.</s>
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            <p type="main">
              <s>The third mill is turned round and round, and not pushed by hand; but
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              between this and the others there is a great distinction, for the lower
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              millstone is so shaped at the top that it can hold within it the upper mill­
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              stone, which revolves around an iron axle; this axle is fastened in the
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              centre of the lower stone and passes through the upper stone. </s>
              <s>A workman,
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              by grasping in his hand an upright iron bar placed in the upper millstone,
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              moves it round. </s>
              <s>The middle of the upper millstone is bored through, and
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              the ore, being thrown into this opening, falls down upon the lower millstone
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              and is there ground to powder, which gradually runs out through its opening;
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              it is washed by various methods before it is mixed with quicksilver,
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              which I will explain presently.</s>
            </p>
            <p type="main">
              <s>Some people build a machine which at one and the same time can crush,
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              grind, cleanse, and wash the gold ore, and mix the gold with quicksilver.
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              </s>
              <s>This machine has one water-wheel, which is turned by a stream striking its
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              buckets; the main axle on one side of the water-wheel has long cams, which
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              raise the stamps that crush the dry ore. </s>
              <s>Then the crushed ore is thrown
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              into the hopper of the upper millstone, and gradually falling through the
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              opening, is ground to powder. </s>
              <s>The lower millstone is square, but has a round
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              depression in which the round, upper millstone turns, and it has an outlet
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              from which the powder falls into the first tub. </s>
              <s>A vertical iron axle is dove­
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              tailed into a cross-piece, which is in turn fixed into the upper millstone;
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              the upper pinion of this axle is held in a bearing fixed in a beam; the drum
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              of the vertical axle is made of rundles, and is turned by the toothed drum
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              on the main axle, and thus turns the millstone. </s>
              <s>The powder falls continually
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              into the first tub, together with water, and from there runs into a second tub
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              which is set lower down, and out of the second into a third, which is the
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              lowest; from the third, it generally flows into a small trough hewn out of a </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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