This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 Excerpt: ...Levick, and the hydraulic slotting machine of Oarrett, Marshall, and Co.; but it would be premature to expross an opinion on their general applicability. CHAPTER XII. AND LONG WOEK. Is the general form in which the colliery is to be laid out determined on, the position of the shafts, main levels, and direction of the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 Excerpt: ...Levick, and the hydraulic slotting machine of Oarrett, Marshall, and Co.; but it would be premature to expross an opinion on their general applicability. CHAPTER XII. AND LONG WOEK. Is the general form in which the colliery is to be laid out determined on, the position of the shafts, main levels, and direction of the working faces settled by local conditions, we have next to solve the question of the best mode of the working away exploitation) of the coal. The most simple and natural method would appear to be, to open ranges of working-places, each as wide as the nature of the floor and roof will admit of with safety, and each divided from its neighbour by masses of coal broad enough to sustain the pressure from above. This is in fact the rudimentary idea of the system of post-and-stall, or bord-and-pillar, stoop-and-room of Scotland). In fullest opposition to this method is that of removing the whole breadth of coal over a long continuous face, supporting the roof at the immediate "face " by temporary props, and allowing the superincumbent strata to break down bodily at a few feet distance behind the workmen--long-wall or long-work. Other modifications there are, which partake more or less of the character of one or other of the above two systems, and which are in vogue in special districts. The post-and-stall work is most largely practised in the Northern collieries; but in one form or another is met with in most coal districts, and is sometimes called for by particular conditions, such as thickness of seam, tenderness of coal, or position of workings beneath sea, rivers, or other surface which must not be disturbed. In the earlier stages of coal mining, it is apt to be the case that the working-spaces (stalls or bards) driven across the grain o...
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