l French machine. en 600 feet into the mountain. This drill cut horizontally The machines used in driving tunnels bore fropi three to aided by a higher temperature than that commonly employed, through 417-J feet of very hard quartz and feldspar rock ; the five holes simultaneously, each in a… … LESCHOT'S DIAMOND-POINTED STEEL DBILL. " Twenty-four men were constantly employed in repairing Fig. 2 represents a " No. 1 Prospecting Drill," so called be eight machines." cause of its general use in testing the character and value of The Commission proceed to say, that, even admitting the mines…
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