Compressed air . BLAST-HOLE DRILLERS OPERATING ON SIDE HILL WORK. stone, flint or quartz in the last fifteen feetof the deep drilling. After such a practical demonstration as thisof the advantages to be obtained by the useof well-drilling machines it was natural thatH. S. Kerbaugh, Inc., should adopt them inconnection with the work at Safe Harbor, al-though it was an entirely different propositionfrom the Enola work. The ground to bedrilled was hard rock of a gneiss mica schistformation with a small percentage of rock varied in hardness and the seamswere at varying angles to the perp
Compressed air . BLAST-HOLE DRILLERS OPERATING ON SIDE HILL WORK. stone, flint or quartz in the last fifteen feetof the deep drilling. After such a practical demonstration as thisof the advantages to be obtained by the useof well-drilling machines it was natural thatH. S. Kerbaugh, Inc., should adopt them inconnection with the work at Safe Harbor, al-though it was an entirely different propositionfrom the Enola work. The ground to bedrilled was hard rock of a gneiss mica schistformation with a small percentage of rock varied in hardness and the seamswere at varying angles to the perpendicular. The average drilling was nineteen feet sixinches per ten-hour shift, but the rate variedgreatly, according to the location. On thewest end of the work, the rate was sixty feetin ten iiours. while at Manns Run, where theholes were from seventy-five to one hundredand twenty-eight feet deep, the rate was elevenfeet per day. At Star Rock one hundred-footholes averaged fourteen feet per ten hours. AtBuzzard
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectcompres, bookyear1896
