Mining in California Volume 8

Mining in California Volume 8

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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. 1888 edition. Excerpt: ...two h_1I1dred feet lower down, and about six hundred feet above the reduction works, is the Day tunnel. This was also started in 1859, and penetrated the mountain to a depth of one thousand five hundred feet. This tunnel b?-S been prolonged outwardly by timber, in order to allow dumping facilities for the work above, that otherwise would have covered up the mouth of the _Day tunnel. The dump of the Myers tunnel above has accumulated and shdden down upon the prolongation until there are over one hundred feet, at the commencement of the Day tunnel, running under this waste roc. All these workings, from the top of the mountain to the Day_ tunnel, constitute the upper portion of the mine, and are connected with each other by various tunnels and upraises. About one hundred feet above the reduction works, and five hundred feet below the Day tunnel, is the Bell 'fi11DI1_e1, 91' lower workings, about four thousand feet in length. This t_1Il' nel is timbered almost throughout its entire length with closely sel/fll1l' b_ers, there being over three thousand sets, with lagging both on the roof and sides. Each set requires a log twenty feet long and ten inches in diameterThe telqllperature in this tunnel is high, and the atmosphere damp and PP1'e5$1Ve-Whether it is the efl'ect of the heat and moisture, of some gaseous exhalation of the formation, is not known; but the timbers decay P1 811 11I1_11s11ally short time, and two men are kept constantly emploled 1" replaclng the Old Ones by new. This rapid decay is more marked dill" mg sultry Weather, When the draft in the tunnel is almost nil, e"_1d the atmosphere 0 pressive. Timbers immersed in Water, or those which are kept constant y Wet by seepage, do not seem more

Product details

  • Paperback | 462 pages
  • 189 x 246 x 24mm | 816g
  • United States
  • English
  • black & white illustrations
  • 1236979311
  • 9781236979315