ords kept.The boiler to furnish the necessary steam is provided,and one of the principal points of the machine is inthe peculiar form of drill used, which penetratesrapidly, bores a truly circular hole without a reamer,and can be sharpened readily at any time with ahammer. Principal among the… … greater number of blows in a given time is also ob-tained, and by the rotation of the tools in the samedirection, a round hole is made, and the wedging oftools prevented. The ability to withdraw and returnthe tools rapidly renders it possible to bore at a depthof 1,000 feet at the same cost per…
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