Engineering and Contracting . y would cross the seams at a veryflat angle and as most of the seams had alittle soft material in them the drills wouldstrike the seams and run off at an angle andjam. thereby causing a lot of lost time. Therock also required a great deal more powderthan if it had-not been so seamy, as at timeswith holes only 2 ft. apart vertically a bedor two beds would be left in between themafter shooting. The rock would break clean-ly to the bottom of the holes, both above andbelow these beds, but they would remainundisturbed. To avoid this it was necessaryeither to use a lot
Engineering and Contracting . y would cross the seams at a veryflat angle and as most of the seams had alittle soft material in them the drills wouldstrike the seams and run off at an angle andjam. thereby causing a lot of lost time. Therock also required a great deal more powderthan if it had-not been so seamy, as at timeswith holes only 2 ft. apart vertically a bedor two beds would be left in between themafter shooting. The rock would break clean-ly to the bottom of the holes, both above andbelow these beds, but they would remainundisturbed. To avoid this it was necessaryeither to use a lot more holes or to loadthe holes considerably heavier. The latterwas the course followed. Wlien sinking theshaft where the drilling was at right angleswith the seams it required about 30 per centless powder per lineal foot of hole and fewerholes were drilled. In the tunnel several different kinds ofpowder were used. The 40 per cent Forcitegelatine dynamite gave fair results and verylittle more of it was required than of the .50. Section of Face
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicago, bookyear19
