Technical paper . ht be sug-gested for this device would be to makeit of hard wood rather than of are two dangers surrounding theuse of a metal instrument. First, nitro-glycerin may get around the pin wherethe jaws work against each other andso cause an explosion by friction. Sec-ond, the lowering of sticks repeatedlyinto the same hole may result in smallbits of dynamite being rubbed off on the Figure for lowering dyna. Walls of the hole or small particles rcmaill-mite into blast holes. . c , i • i mg on the jaws ot the instrument, andthese may be struck between the iron
Technical paper . ht be sug-gested for this device would be to makeit of hard wood rather than of are two dangers surrounding theuse of a metal instrument. First, nitro-glycerin may get around the pin wherethe jaws work against each other andso cause an explosion by friction. Sec-ond, the lowering of sticks repeatedlyinto the same hole may result in smallbits of dynamite being rubbed off on the Figure for lowering dyna. Walls of the hole or small particles rcmaill-mite into blast holes. . c , i • i mg on the jaws ot the instrument, andthese may be struck between the iron and the rock surface inhauling the device from the hole. PREPARATION FOR FIRING. As regards methods of blasting, the greatest danger in blasting isfrom delayed blasts, partly exploded charges, and misfires. If aseries of holes are shot at the same time, the failure of one or morecharges to explode may not be observed, and subsequent operationsmay cause the discharge of the explosive in the missed holes. In the. SAFETY IN QUARRY METHODS. 21 case of incomplete detonation, pieces of dynamite or some unexplodedpowder may be scattered among rock fragments and thus constitute agrave danger if struck by metal tools. Where explosions are delayed^there is risk in a too hasty approach to the danger zone. Conse-quently the methods emphasized relate to complete detonation andavoidance of misfires. ELECTRIC AND FUSE FIRING. Electric firing is to be preferred to fuse as the results are instan-taneous and there is no waiting in suspense; moreover, there is prac-tically no danger of delayed explosions. In order to obtain completedischarge the use of detonators is recommended. If fuse is employed,it should be inserted gently into the detonator and crimped with aproper tool. The rate of burning of the fuse should be known approxi-mately, and sufficient length allowed to permit escape to a safedistance. Fuse should be kept dry and handled carefully, it shouldnot be bent suddenly when stiff from
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
