Bulletin . Sca/e200 30O 4O0 500 ft. Figure 27.—One method of working Roslyn bed in Roslyn field; also arrangement of surface Buildings. EASTERN WASHINGTON. 63 enough to make impossible the separation of impurities coal breaks in rather large lumps and has a bright, -lean surface;therefore it finds a ready market in competition with other coalsof less pleasing appearance. The smaller sizes are washed and arereadily sold in the steam and gascoal markets. The general plan of operationin this field is shown in Figure slope is usually sunk on thefull dip of the bed. Parallel
Bulletin . Sca/e200 30O 4O0 500 ft. Figure 27.—One method of working Roslyn bed in Roslyn field; also arrangement of surface Buildings. EASTERN WASHINGTON. 63 enough to make impossible the separation of impurities coal breaks in rather large lumps and has a bright, -lean surface;therefore it finds a ready market in competition with other coalsof less pleasing appearance. The smaller sizes are washed and arereadily sold in the steam and gascoal markets. The general plan of operationin this field is shown in Figure slope is usually sunk on thefull dip of the bed. Parallel tothe slope and separated from it bya pillar about 100 feet wide isthe return airway. Crosscuts aredriven every 50 or 60 feet. Figure 28 shows the dimensions ofslopes as ordinarily driven and also indicates that single tracksare Figure 28.—Dimensions of single slope,Roslyn bed, Roslyn field. GANGWAYS OR ENTRIES. Coal ?8- rz Coal Figure 29.—One method of driving gang-way or entry. Roslyn bed. Roslyn field. Gangways or entries are turnedfrom the main slope at intervalsof 300 to 500 feet. These entriesare from 8 to 11 feet wide and aredriven to the height of the coalseam. The method of driving themis shown in Figures 29 and or two and one-half sticks of a permissible explosive areplaced in each hole, which is then tamped with clay. The shotsare fired by shot fixers at the close of the shift. Safety fuses are used when gas is present. _ It was formerly the custom to ^S^TTI^g^:::::::::::^^drive entries 16 feet wide and touse one side for gobbing the wasterock, leaving a clearance of 8 feetfor haulage purposes. Under the method now followed,the cap rock is removed from themine when it is taken down. Re-turn entries are driven parallel to the main entries or gangways, usually on the dip side, and sepa
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
