Agricola, Georgius, De re metallica, 1912/1950

Table of figures

< >
[Figure 161]
Page: 332
[Figure 162]
Page: 334
[Figure 163]
Page: 337
[Figure 164]
Page: 339
[Figure 165]
Page: 340
[Figure 166]
Page: 341
[Figure 167]
Page: 343
[Figure 168]
Page: 344
[Figure 169]
Page: 345
[Figure 170]
Page: 346
[Figure 171]
Page: 347
[Figure 172]
Page: 349
[Figure 173]
Page: 351
[Figure 174]
Page: 352
[Figure 175]
Page: 353
[Figure 176]
Page: 355
[Figure 177]
Page: 356
[Figure 178]
Page: 358
[Figure 179]
Page: 359
[Figure 180]
Page: 360
[Figure 181]
Page: 361
[Figure 182]
Page: 362
[Figure 183]
Page: 364
[Figure 184]
Page: 365
[Figure 185]
Page: 366
[Figure 186]
Page: 367
[Figure 187]
Page: 368
[Figure 188]
Page: 369
[Figure 189]
Page: 370
[Figure 190]
Page: 371
< >
page |< < of 679 > >|
    <archimedes>
      <text>
        <body>
          <chap>
            <p type="main">
              <s>
                <pb pagenum="128"/>
              avoid wearing away their clothes and injuring their left shoulders they
                <lb/>
              usually bind on themselves small wooden cradles. </s>
              <s>For this reason, this
                <lb/>
              particular class of miners, in order to use their iron tools, are obliged to bend
                <lb/>
              their necks to the left, not infrequently having them twisted. </s>
              <s>Now these
                <lb/>
              veins also sometimes divide, and where these parts re-unite, ore of a richer and
                <lb/>
              a better quality is generally found; the same thing occurs where the stringers,
                <lb/>
              of which they are not altogether devoid, join with them, or cut them crosswise,
                <lb/>
              or divide them obliquely. </s>
              <s>To prevent a mountain or hill, which has in
                <lb/>
              this way been undermined, from subsiding by its weight, either some natural
                <lb/>
              pillars and arches are left, on which the pressure rests as on a foundation, or
                <lb/>
              timbering is done for support. </s>
              <s>Moreover, the materials which are dug out
                <lb/>
              and which are devoid of metal are removed in bowls, and are thrown back,
                <lb/>
              thus once more filling the caverns.</s>
            </p>
            <p type="main">
              <s>Next, as to
                <emph type="italics"/>
              venæ cumulatæ.
                <emph.end type="italics"/>
              </s>
              <s> These are dug by a somewhat different
                <lb/>
              method, for when one of these shows some metal at the top of the ground,
                <lb/>
              first of all one shaft is sunk; then, if it is worth while, around this one many
                <lb/>
              shafts are sunk and tunnels are driven into the mountain. </s>
              <s>If a torrent or
                <lb/>
              spring has torn fragments of metal from such a vein, a tunnel is first driven
                <lb/>
              into the mountain or hill for the purpose of searching for the ore; then
                <lb/>
              when it is found, a vertical shaft is sunk in it. </s>
              <s>Since the whole mountain, or
                <lb/>
              more especially the whole hill, is undermined, seeing that the whole of it is
                <lb/>
              composed of ore, it is necessary to leave the natural pillars and arches, or the
                <lb/>
              place is timbered. </s>
              <s>But sometimes when a vein is very hard it is broken by
                <lb/>
              fire, whereby it happens that the soft pillars break up, or the timbers are
                <lb/>
              burnt away, and the mountain by its great weight sinks into itself, and then
                <lb/>
              the shaft buildings are swallowed up in the great subsidence. </s>
              <s>Therefore,
                <lb/>
              about a
                <emph type="italics"/>
              vena cumulata
                <emph.end type="italics"/>
              it is advisable to sink some shafts which are not sub­
                <lb/>
              ject to this kind of ruin, through which the materials that are excavated may
                <lb/>
              be carried out, not only while the pillars and underpinnings still remain whole
                <lb/>
              and solid, but also after the supports have been destroyed by fire and have
                <lb/>
              fallen. </s>
              <s>Since ore which has thus fallen must necessarily be broken by fire,
                <lb/>
              new shafts through which the smoke can escape must be sunk in the abyss.
                <lb/>
              </s>
              <s>At those places where stringers intersect, richer ore is generally obtained
                <lb/>
              from the mine; these stringers, in the case of tin mines, sometimes have in
                <lb/>
              them black stones the size of a walnut. </s>
              <s>If such a vein is found in a plain,
                <lb/>
              as not infrequently happens in the case of iron, many shafts are sunk, because
                <lb/>
              they cannot be sunk very deep. </s>
              <s>The work is carried on by this method
                <lb/>
              because the miners cannot drive a tunnel into a level plain of this kind.</s>
            </p>
            <p type="main">
              <s>There remain the stringers in which gold alone is sometimes found,
                <lb/>
              in the vicinity of rivers and streams, or in swamps. </s>
              <s>If upon the soil being
                <lb/>
              removed, many of these are found, composed of earth somewhat baked and
                <lb/>
              burnt, as may sometimes be seen in clay pits, there is some hope that gold
                <lb/>
              may be obtained from them, especially if several join together. </s>
              <s>But the
                <lb/>
              very point of junction must be pierced, and the length and width searched
                <lb/>
              for ore, and in these places very deep shafts cannot be sunk.</s>
            </p>
            <p type="main">
              <s>I have completed one part of this book, and now come to the other, in
                <lb/>
              which I will deal with the art of surveying. </s>
              <s>Miners measure the solid </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
Impressum