Agricola, Georgius, De re metallica, 1912/1950
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              <s>Now when a miner discovers a
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              vena profunda
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              he begins sinking a shaft
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              and above it sets up a windlass, and builds a shed over the shaft to prevent
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              the rain from falling in, lest the men who turn the windlass be numbed
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              by the cold or troubled by the rain. </s>
              <s>The windlass men also place their
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              barrows in it, and the miners store their iron tools and other implements therein.
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              </s>
              <s>Next to the shaft-house another house is built, where the mine foreman and the
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              other workmen dwell, and in which are stored the ore and other things which
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              are dug out. </s>
              <s>Although some persons build only one house, yet because
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              sometimes boys and other living things fall into the shafts, most miners
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              deliberately place one house apart from the other, or at least separate them
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              by a wall.</s>
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              <s>Now a shaft is dug, usually two fathoms long, two-thirds of a fathom
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              wide, and thirteen fathoms deep; but for the purpose of connecting with a
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              tunnel which has already been driven in a hill, a shaft may be sunk to a
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              depth of only eight fathoms, at other times to fourteen, more or less
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              3
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              . </s>
              <s>A
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              shaft may be made vertical or inclined, according as the vein which the
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              miners follow in the course of digging is vertical or inclined. </s>
              <s>A tunnel is a
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              subterranean ditch driven lengthwise, and is nearly twice as high as it is
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              broad, and wide enough that workmen and others may be able to pass and
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              carry their loads. </s>
              <s>It is usually one and a quarter fathoms high, while
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              its width is about three and three-quarters feet. </s>
              <s>Usually two workmen are
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              required to drive it, one of whom digs out the upper and the other the lower
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              part, and the one goes forward, while the other follows closely after. </s>
              <s>Each
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              sits upon small boards fixed securely from the footwall to the hangingwall,
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              or if the vein is a soft one, sometimes on a wedge-shaped plank fixed on to the
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              vein itself. </s>
              <s>Miners sink more inclined shafts than vertical, and some of each
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              kind do not reach to tunnels, while some connect with them. </s>
              <s>But as for
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              some shafts, though they have already been sunk to the required depth,
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              the tunnel which is to pierce the mountain may not yet have been driven
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              far enough to connect with them.</s>
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              <s>It is advantageous if a shaft connects with a tunnel, for then the miners
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              and other workmen carry on more easily the work they have undertaken;
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              but if the shaft is not so deep, it is usual to drift from one or both sides of it.
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              </s>
              <s>From these openings the owner or foreman becomes acquainted with the
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              veins and stringers that unite with the principal vein, or cut across it, or </s>
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