Mining and Scientific Press Volume 116

Mining and Scientific Press Volume 116

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 edition. Excerpt: ...3.5 lb. cassiterite per yard, and the dredge returned about 5 lb. per yard. This, of course, is on the safe side, but there are places were such differences might be sufficient to condemn a venture. The best way to avoid this inaccuracy is to drill more holes and to use a suction-pump. As soon as I suggested that possibly some of the Lena ground might be worked more advantageously by dredging, the Russian engineers on the property said it was impossible, because all the gold was in the bedrock. In order to test this statement, I requested A. J. Heindel to make a graphic presentation of the gold in each hole. This he did, and, as we had a cross-section of each line of holes, when the values were shown graphically on this section, one could see where the gold was concentrated. After having completed a few of these it was definitely settled that fully 98% of the gold was above bedrock. Even if it had been on the bedrock, there was no reason why the dredge should not have recovered it, as the bedrock is sedimentary just as in the Klondike and in Alaska. The drilling machines are numbered. A map on a scale of 175 ft. to the inch was used. On this each line of holes was marked, and also each hole. A pin with a number represented the machine. This pin marked the point where the machine was drilling. If a machine was in the repair-shop, or was being moved, it was indicated by a pin stuck in a card hanging on the wall. There was a black blank on this card, so that each 24 hours of work could be marked with chalk, indicating every day the site of each machine, and the progress made, so that anyone wishing to know anything in reference to the drills could walk into the room and see at a glance just how things were progressing. This is of great...show more

Product details

  • Paperback | 864 pages
  • 189 x 246 x 43mm | 1,510g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 123697834X
  • 9781236978349