Agricola, Georgius, De re metallica, 1912/1950

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              into a dish placed underneath to prevent any of the metal from falling to
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              the ground. </s>
              <s>They break a hard vein loose from the footwall by blows with
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              a hammer upon the first kind of iron tool
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              13
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              , all of which are designated by
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              appropriate names, and with the same tools they hew away the hard hanging­
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              wall rock. </s>
              <s>They hew out the hangingwall rock in advance more frequently, the
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              rock of the footwall more rarely; and indeed, when the rock of the footwall
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              resists iron tools, the rock of the hangingwall certainly cannot be broken unless
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              it is allowable to shatter it by fire. </s>
              <s>With regard to the harder veins which are
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              tractable to iron tools, and likewise with regard to the harder and hardest
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              kind of hangingwall rock, they generally attack them with more powerful
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              iron tools, in fact, with the fourth kind of iron tool, which are called by their
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              appropriate names; but if these are not ready to hand, they use two or
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              three iron tools of the first kind together. </s>
              <s>As for the hardest kind of metal­
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              bearing vein, which in a measure resists iron tools, if the owners of the
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              neighbouring mines give them permission, they break it with fires. </s>
              <s>But if
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              these owners refuse them permission, then first of all they hew out the rock of
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              the hangingwall, or of the footwall if it be less hard; then they place timbers
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              set in hitches in the hanging or footwall, a little above the vein, and from
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              the front and upper part, where the vein is seen to be seamed with small
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              cracks, they drive into one of the little cracks one of the iron tools which
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              I have mentioned; then in each fracture they place four thin iron
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              blocks, and in order to hold them more firmly, if necessary, they place
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              as many thin iron plates back to back; next they place thinner iron
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              plates between each two iron blocks, and strike and drive them by
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              turns with hammers, whereby the vein rings with a shrill sound; and the
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              moment when it begins to be detached from the hangingwall or footwall
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              rock, a tearing sound is heard. </s>
              <s>As soon as this grows distinct the miners
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              hastily flee away; then a great crash is heard as the vein is broken and torn,
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              and falls down. </s>
              <s>By this method they throw down a portion of a vein weigh­
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              ing a hundred pounds more or less. </s>
              <s>But if the miners by any other method
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              hew the hardest kind of vein which is rich in metal, there remain certain
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              cone-shaped portions which can be cut out afterward only with difficulty. </s>
              <s>As
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              for this knob of hard ore, if it is devoid of metal, or if they are not allowed to
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              apply fire to it, they proceed round it by digging to the right or left, because
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              it cannot be broken into by iron wedges without great expense. </s>
              <s>Meantime,
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              while the workmen are carrying out the task they have undertaken, the
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              depths of the earth often resound with sweet singing, whereby they lighten a
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              toil which is of the severest kind and full of the greatest dangers.</s>
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              <s>As I have just said, fire shatters the hardest rocks, but the method of its
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              application is not simple
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              14
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              . </s>
              <s>For if a vein held in the rocks cannot be hewn
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              </s>
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