Gold And Silver Comprising An Economic History of Mining in the United States
Gold And Silver Comprising An Economic History of Mining in the United States
Walter R Walter Richard Crane
The book Gold And Silver Comprising An Economic History of Mining in the United States was written by author Walter R Walter Richard Crane Here you can read free online of Gold And Silver Comprising An Economic History of Mining in the United States book, rate and share your impressions in comments. If you don't know what to write, just answer the question: Why is Gold And Silver Comprising An Economic History of Mining in the United States a good or bad book?
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Tunnels as distinguished from drifts do not follow the vein but usually run normal to the stratification of the rocks and therefore cut the vein transversely. Shafts and drifts prove the vein-contents over a large area while tunneling is more in the nature of drilling in that respect. The special advantage of tunneling consists in exploring ground lying without the vein and locating the so-called " blind " deposits, i. E. , those that do not come to the surface. Drilling has all of the advantag...es of shafts, drifts and tunnels with respect to position as holes can be drilled in any direction, but the results obtained are lacking in definiteness and detail. The following comparison between shalt sinking and drilling as means of prospecting has been given: 1 A shaft can be sunk 100 feet in four months at a cost of $3, 000, while with the same expendi- ture 10 holes could be drilled with a diamond drill to the same depth and spaced 10 feet apart in about two and one-half months. In the latter case a block of ground x 100 feet square and deep will have been fairly well explored, while in the former case only the cubical contents of the shaft will be positively known.
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