Official documents, comprising the department and other reports made to the Governor, Senate and House of Representatives of Pennsylvania . e^a-ieuj-t^y qcc^H^-V-a.^ Longwall in steps. Faces advancing on level course. FIG. 2. <i. Crpss (^af^u>^y. CtoZ% Qa2e/iSTxy. Longwall in steps. Faces advancing to full rise. No. 10. BUREAU OF MINES. 13 down which the tubs are lowered to a cross gateway along which theyare taken to a main incline. The following diagrams, Figures 1 and2, illustrate these methods of working: In some of the comparatively flat parts of the seams, a system ofpillar ~u ork
Official documents, comprising the department and other reports made to the Governor, Senate and House of Representatives of Pennsylvania . e^a-ieuj-t^y qcc^H^-V-a.^ Longwall in steps. Faces advancing on level course. FIG. 2. <i. Crpss (^af^u>^y. CtoZ% Qa2e/iSTxy. Longwall in steps. Faces advancing to full rise. No. 10. BUREAU OF MINES. 13 down which the tubs are lowered to a cross gateway along which theyare taken to a main incline. The following diagrams, Figures 1 and2, illustrate these methods of working: In some of the comparatively flat parts of the seams, a system ofpillar ~u ork is in vogue; levels are driven atoout 11 yards apart, centreto centre, leaving a pillar of about 8f yards between them. Thesepillars are worked off in portions (lifts) 13 feet wide at a time. The main roadways were well lined by masonry, steel or timber,and were in excellent order; here there was very little chance of any-one being injured by a fall. It is more important to consider thebranch roadways and working faces, the latter especially being sub-ject to accidents from falls of roof or side. The chief points to be con-sidered are: Mateiial employed, method of setting the timber, methodof drawing the timber, cost of timb
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherslsn, bookyear1887
