Principles of mining : valuation, organization and administration; copper, gold, lead, silver, tin and zinc . Fig. 4. — Cross-sections showing entry to vertical or horizontal deposits. Case Fig. 5. — Cross-section showing alternative shafts to inclined deposit to be worked from surface. Case III. 63 64 PRINCIPLES OF MINING. struction, subsequent operation, and the useful life of the shaft,and these matters are largely governed by the degree of a shaft of the same size in either alternative, the com-parative cost per foot of sinking is dependent largely on thebreaking faciliti
Principles of mining : valuation, organization and administration; copper, gold, lead, silver, tin and zinc . Fig. 4. — Cross-sections showing entry to vertical or horizontal deposits. Case Fig. 5. — Cross-section showing alternative shafts to inclined deposit to be worked from surface. Case III. 63 64 PRINCIPLES OF MINING. struction, subsequent operation, and the useful life of the shaft,and these matters are largely governed by the degree of a shaft of the same size in either alternative, the com-parative cost per foot of sinking is dependent largely on thebreaking facilities of the rock under the different directions ofattack. In this, the angles of the bedding or joint planes to thedirection of the shaft outweigh other factors. The shaft whichtakes the greatest advantage of such lines of breaking weaknesswill be the cheapest per foot to sink. In South African experi-ence, where inclined shafts are sunk parallel to the beddingplanes of hard quartzites, the cost per foot appears to be infavor of the incline. On the other hand, sinking shafts acrosstight schists seems to be more advantageous than parallel to thebedding planes, and inclines following the d
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