Bulletin . he gangwajT of the lift both the retreating and advancing methods the pillars betweenbreasts are withdrawn after a certain number of pillars have beendriven to their limits. In the breast and pillar system, as well as in the chute and pillarsystem, chutes from 6 to 8 feet wide are driven from the gangwayto the first counter; where this is above the gangway, as it com-monly is, the chutes are continued narrow for the first 12 to 20 feetabove the counter. At this point, if the breast is to be wide, it iscustomary to begin widening and to continue gradually until thefull width
Bulletin . he gangwajT of the lift both the retreating and advancing methods the pillars betweenbreasts are withdrawn after a certain number of pillars have beendriven to their limits. In the breast and pillar system, as well as in the chute and pillarsystem, chutes from 6 to 8 feet wide are driven from the gangwayto the first counter; where this is above the gangway, as it com-monly is, the chutes are continued narrow for the first 12 to 20 feetabove the counter. At this point, if the breast is to be wide, it iscustomary to begin widening and to continue gradually until thefull width is reached. The breast is then carried at its full widthto the limit of the lift. Faults are sometimes encountered and anarrow place about the width of the chute is driven through thefaulted ground, with a manway on one side and a coal chute on theother. The method of timbering the chutes at one mine is shown inFigure 12. The boarding on the side, commonly the inby side, of ? Hoisting mngino |»- -£P %_. O^ 3CX
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
