Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <pb pagenum="106"/>
            <p type="main">
              <s>I have spoken of shafts, tunnels, and drifts. </s>
              <s>I will now speak of the
                <lb/>
              indications given by the
                <emph type="italics"/>
              canales,
                <emph.end type="italics"/>
              by the materials which are dug out, and by
                <lb/>
              the rocks. </s>
              <s>These indications, as also many others which I will explain, are
                <lb/>
              to a great extent identical in
                <emph type="italics"/>
              venae dilatatae
                <emph.end type="italics"/>
              and
                <emph type="italics"/>
              venae cumulatae
                <emph.end type="italics"/>
              with
                <emph type="italics"/>
              venae
                <lb/>
              profundae.
                <emph.end type="italics"/>
              </s>
            </p>
            <p type="main">
              <s>When a stringer junctions with a main vein and causes a swelling, a
                <lb/>
              shaft should be sunk at the junction. </s>
              <s>But when we find the stringer inter­
                <lb/>
              secting the main vein crosswise or obliquely, if it descends vertically down
                <lb/>
              to the depths of the earth, a second shaft should be sunk to the point where
                <lb/>
              the stringer cuts the main vein; but if the stringer cuts it obliquely the
                <lb/>
              shaft should be two or three fathoms back, in order that the junction may
                <lb/>
              be pierced lower down. </s>
              <s>At such junctions lies the best hope of finding the
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              ore for the sake of which we explore the ground, and if ore has already been
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              found, it is usually found in much greater abundance at that spot. </s>
              <s>Again,
                <lb/>
              if several stringers descend into the earth, the miner, in order to pierce
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              through the point of contact, should sink the shaft in the midst of these
                <lb/>
              stringers, or else calculate on the most prominent one.</s>
            </p>
            <p type="main">
              <s>Since an inclined vein often lies near a vertical vein, it is advisable
                <lb/>
              to sink a shaft at the spot where a stringer or cross-vein cuts them both;
                <lb/>
              or where a
                <emph type="italics"/>
              vena dilatata
                <emph.end type="italics"/>
              or a stringer
                <emph type="italics"/>
              dilatata
                <emph.end type="italics"/>
              passes through, for minerals
                <lb/>
              are usually found there. </s>
              <s>In the same way we have a good prospect of finding
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              metal at the point where an inclined vein joins a vertical one; this is why
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              miners cross-cut the hangingwall or footwall of a main vein, and in these
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              openings seek for a vein which may junction with the principal vein a few
                <lb/>
              fathoms below. </s>
              <s>Nay, further, these same miners, if no stringer or cross­
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              vein intersects the main vein so that they can follow it in their workings,
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              even cross-cut through the solid rock of the hangingwall or footwall. </s>
              <s>These
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              cross-cuts are likewise called “
                <foreign lang="grc">κρυπταί,</foreign>
              ” whether the beginning of the
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              opening which has to be undertaken is made from a tunnel or from a drift.
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              </s>
              <s>Miners have some hope when only a cross vein cuts a main vein. </s>
              <s>Further,
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              if a vein which cuts the main vein obliquely does not appear anywhere
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              beyond it, it is advisable to dig into that side of the main vein toward which
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              the oblique vein inclines, whether the right or left side, that we may ascer­
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              tain if the main vein has absorbed it; if after cross-cutting six fathoms it
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              is not found, it is advisable to dig on the other side of the main vein, that
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              we may know for certain whether it has carried it forward. </s>
              <s>The owners
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              of a main vein can often dig no less profitably on that side where the vein
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              which cuts the main vein again appears, than where it first cuts it; the
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              owners of the intersecting vein, when that is found again, recover their title,
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              which had in a measure been lost.</s>
            </p>
            <p type="main">
              <s>The common miners look favourably upon the stringers which come
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              from the north and join the main vein; on the other hand, they look
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              unfavourably upon those which come from the south, and say that these do
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              much harm to the main vein, while the former improve it. </s>
              <s>But I think
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              that miners should not neglect either of them: as I showed in Book III,
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              experience does not confirm those who hold this opinion about veins, so now </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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