Agricola, Georgius, De re metallica, 1912/1950
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              rotates with it; therefore, when the axle revolves, the little axle and
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              the bronze tube in their turn raise the tooth and the stamp. </s>
              <s>When the
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              little iron axle and the bronze pipe have been taken out of the arms, the tooth
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              of the stamps is not raised, and other stamps may be raised without this one.
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              <s>Further on, a drum with spindles fixed around the axle of a water-wheel
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              moves the axle of a toothed drum, which depresses the sweeps of the bellows
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              in the adjacent fourth part of the building; but it turns in the contrary
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              direction; for the axis of the drum which raises the stamps turns toward
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              the north, while that one which depresses the sweeps of the bellows turns
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              toward the south.</s>
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              <s>Those cakes which are too thick to be rapidly broken by blows from
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              the iron-shod stamp, such as are generally those which have settled in the
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              bottom of the crucible,
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              9
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              are carried into the first part of the building. </s>
              <s>They
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              are there heated in a furnace, which is twenty-eight feet distant from the
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              second long wall and twelve feet from the second transverse wall. </s>
              <s>The three
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              sides of this furnace are built of rectangular rocks, upon which bricks are laid;
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              the back furnace wall is three feet and a palm high, and the rear of the side
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              walls is the same; the side walls are sloping, and where the furnace is open in
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              front they are only two feet and three palms high; all the walls are a foot and
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              a palm thick. </s>
              <s>Upon these walls stand upright posts not less thick, in order
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              that they may bear the heavy weight placed upon them, and they are covered
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              with lute; these posts support the sloping chimney and penetrate through
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              the roof. </s>
              <s>Moreover, not only the ribs of the chimney, but also the rafters,
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              are covered thickly with lute. </s>
              <s>The hearth of the furnace is six feet
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              long on each side, is sloping, and is paved with bricks. </s>
              <s>The cakes of copper
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              are placed in the furnace and heated in the following way. </s>
              <s>They are first of
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              all placed in the furnace in rows, with as many small stones the size of an egg
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              between, so that the heat of the fire can penetrate through the spaces between
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              them; indeed, those cakes which are placed at the bottom of the crucible are
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              each raised upon half a brick for the same reason. </s>
              <s>But lest the last row,
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              which lies against the mouth of the furnace, should fall out, against the mouth
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              are placed iron plates, or the copper cakes which are the first taken from the
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              crucible when copper is made, and against them are laid exhausted liquation
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              cakes or rocks. </s>
              <s>Then charcoal is thrown on the cakes, and then live coals;
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              at first the cakes are heated by a gentle fire, and afterward more charcoal is
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              added to them until it is at times three-quarters of a foot deep. </s>
              <s>A fiercer fire
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              is certainly required to heat the hard cakes of copper than the fragile ones.
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              </s>
              <s>When the cakes have been sufficiently heated, which usually occurs within
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              the space of about two hours, the exhausted liquation cakes or the rocks
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              and the iron plate are removed from the mouth of the furnace. </s>
              <s>Then the
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              hot cakes are taken out row after row with a two-pronged rabble, such as the
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              one which is used by those who “dry” the exhausted liquation cakes.
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              </s>
              <s>Then the first cake is laid upon the exhausted liquation cakes, and beaten by
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              two workmen with hammers until it breaks; the hotter the cakes are, the </s>
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