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Show NEW IDEA IN EXCAVATING Hydraulic Mining Cartridge Is Said to Be the Most Powerful Yet Devised. It is often hard, and sometimes dangerous, dan-gerous, to use ordinary explosives for mining and excavating In confined spaces, a fact that has led to the development de-velopment of the hydraulic mining j cartridge as a safe and effective sub-.. sub-.. stitute. The cartridge consists of a j steel cylinder containing numerous small pistons that expand when water g is injected into them with a hand pump. After drilling a deep enough I- hole, the workmen insert the cylinder, a and then set to work at the hand e pump. The tiny pistons expand until their free extremities bear against the e mass of rock with constantly-increas-k ing force, and the rock is gradually 5 fractured under the tremendous pres-i pres-i sure. The operation, it is said, is not only cheaper than the ordinary blast but disintegrates a larger area of rock. |