Triumphs and wonders of the 19th century, a volume of original, historic and descriptive writings showing the many and marvellous achievements which distinguish an hundred years of material, intellectual, social and moral progress (1901)
Boyd, James Penny, 1836-1910 · Philadelphia, A. J. Holman & co · leaf 612
with the tents of speculators and geologists,has grown up a multitude of towns, filled with thousands of people whoselabors are performed at a depth of nearly a mile under ground. Thousandsmore transport the ore to the mills, separate the copper from the rock, andcut timber for the mines ; while… … THE SERGEANT ROCK DRILL. This district is the only one in the United States where the man-enginehas been used ; but as the shafts were sunk deeper and deeper, it was foundthat even this method was not sufficiently rapid, and the men are now low-ered into the mines by cages or skips. A cage is…
Progress · Inventions
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