This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...mostly by gravity. The disadvantage is that there is a limit to the depth at Figs. 74 And 75.--Lagging Arrangement, Old Ironsides Mine. which the ore can be excavated, because of the caving or falling in of the sides. On the deeper levels of the mine the usual method of underground development was carried out. The ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...mostly by gravity. The disadvantage is that there is a limit to the depth at Figs. 74 And 75.--Lagging Arrangement, Old Ironsides Mine. which the ore can be excavated, because of the caving or falling in of the sides. On the deeper levels of the mine the usual method of underground development was carried out. The system of mining the ore was very similar to that in vogue in the Le Roi, which has been already described. The timbers, however, were stouter, and the method of lagging was different. In arranging the lagging the object was to place it in such a way that the broken ore could be rolled into the chutes with the least possible amount of shoveling. To accomplish this, lagging about 10 ft. long was laid on the caps, close together, and, if the poles were weak, perhaps a double layer. A space two sets square had the poles laid parallel, and the adjacent squares were poled at right angles to these. The caps and collar braces were of the same dimensions, hence it did not matter which way the lagging was arranged. In this way the poles had a good support at both ends, because they reached well over two 5-ft. sets. When it was desired to remove the muck, all that was necessary was to move a pole so that the ore could drop through. As it rolled down, with the aid of a pick or bar, another and another pole could be rolled from beneath it. In this manner the writer has rolled into the chute 40 or 50 tons in four or five hours. Any very large boulders, of course, were smashed with a sledge hammer. Fig. 75 is meant to show the arrangement of the lagging. It is a plan of the floor immediately under the ore to be mined, while Fig. 74 is an elevation of the same. Fias. 76 And 77.--Chute Arkanciement, Old Ironsides Mine. A special method of chute building was adopt...
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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illus. GOOD only. 179pp. Owner's name FEP, 1 1/2" split on front hinge. "Gift to NMSM Library" stamp title page, stamped 'discard'. EX LIB, usual wear.
