Bulletin . r rib, le spacebetwen la large nervure et les beingused la voie pour le stockage des déchets. Recoupe6 pieds de largeur sont entraînés betweenrooms à intervalles de 60 pieds. La méthode de traitement des voitures dans les chambres dépend de la chute du lit. Où le dip rangesfrom 0° à 4° les voitures sont pusheddirectly au visage, mais thedip où est de 4° à 18°, Cordes-andsheaves McGinties ou-sont utilisés, l'ordre décroissant les pullingup wagon chargé vide. Figure 31 illustratesthe la disposition des pistes, andFigure 32 donne les détails de thesheave et de sa fixation. Lorsque le pendage du lit est plus environ 18° feuille-fer à repasser

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Bulletin . r rib, the wide spacebetwen the rib and the track beingused for storing refuse. Crosscuts6 feet wide are driven betweenrooms at intervals of 60 feet. The method of handling cars inthe rooms depends on the dip ofthe bed. Where the dip rangesfrom 0° to 4° the cars are pusheddirectly to the face, but where thedip is from 4° to 18°, ropes andsheaves—or McGinties—are used, the descending loaded car pullingup the empty. Figure 31 illustratesthe arrangement of the tracks, andFigure 32 gives the details of thesheave and its fastening. When the dip of the bed is morethan about 18° sheet-iron chutesare built along one rib and wing chutes direct the coal from theother side of the working face to the chute, Figure 33. Four lines ofprops are set on 4-foot centers. The air is carried to the workingface by means of a brattice cloth fastened to the props. The bestresults are obtained by carrying the face in a direction diagonal tothe dip of the bed, the work being easy and little powder being. <b Entry Figdee 31.—One method of mining rooms, using cars to face. EASTERN WASHINGTON. 65 required. The coal is undercut for a depth of 3 feet, and one smallshot is placed in the upper left-hand corner of the room. CUTTING THE COAL AND SHOT FIHING. Most of the coal produced in this county is mined with picks. Postpunchers have been tried, but they are less satisfactory than handwork. In 1917 only 0.33 per centof the total coal mined was under- ^ma^ ^°^ cut by machines, 77.86 per cent wasmined by hand, and 21.81 per centwas shot off the solid. The ex-plosives used were: 56.2 per centblack powder, 1.8 per cent dyna-mite, and 42 per cent permissibles.When the coal is cut with picksbefore shooting the mining is madein either the top or bottom of thebed and the coal is shot down orup, as seems preferable. When thecoal is shot off the solid from fiveto six holes are usually placed inthe face, bored 5 or 6 feet in depth. Since gas is found in some mines, precautions are taken

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