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Progress report on investigation of detachable rock-drill bits
Hot milling of rock-drill bits at the mines of the Vinegar Hill Zinc Co., Platteville, Wis.
Progress report no. 2 on investigation of detachable rock-drill bits
Progress report 4 on investigation of detachable rock-drill bits
Progress report no. 3 on investigation of detachable rock-drill bits
Diamond-drilling blast holes, eastern Magnetite Mine A
Diamond drilling blast holes, Balmat Mine, St. Lawrence County, N.Y.
Shaft sinking by diamond drilling, Bellefonte mine, National Gypsum Co., Centre County, Pa.
Diamond-drilling blast holes, Bellefonte Mine, National Gypsum Co., Centre County, Pa.
Diamond-drilling blast holes, Eastern Magnetite Mine C
Lightweight fiberglass feed leg for hand-held pneumatic percussion rock drills