328 



In forming the pillars and carrying forwards the boards with regularity, especially 

 where the backs and cutters are very distinct and numerous, it is of importance to 



1507 



1508 



1509 



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ICED 



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D DEE P EEEiaia 

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work the rooms at right angles to the backs, 

 and the thirlings in the direction of the cutters, 

 however oblique these may be to the backs, as 

 the rooms are by this means conducted with 

 greatest regularity with regard to each other, 

 kept equidistant, and the pillars are strongest under a given area. At the same time, 

 however, it seldom happens that a back or cutter occurs exactly at the place where a 

 pillar is formed ; but this is of no consequence, as the shearing or cutting made by the 

 miner ought to be in a line parallel to the backs and cutters. It frequently happens 

 that the dip-head level intersects the cutters in its progress at a very oblique angle. In 

 this case, when rooms and pillars are set off, the face of the pillar and width of the 

 room must be measured off an exact breadth in proportion to the obliquity, as in jig. 

 1508. By neglect of this rule much confusion and irregular work is often produced. 

 It is, moreover, proper to make the first set of pillars next the dip-head level much 

 stronger, even where there is no obliquity, in order to protect that level froni being 

 injured by any accidental crush of the strata. 



We shall now explain the different systems of working : one of the simplest of which 

 is shown in fig. 1509 : where A represents the engine-pit; B, the bye-pit; c, D, the 

 dip-head levels, always carried in advance of the rooms ; and B, the rise- or crop- 

 gallery, also carried in advance. These galleries not only open out the work for the 

 miners in the coal-bed, but, being in advaace, afford sufficient time for any requisite 

 operation, should the mines be obstructed by dykes or hitches. In the example before 

 tis, the room or boards are worked from the dip to the crop ; the leading rooms, or 

 those most in advance, are on each side of the crop-gallery E ; all the other rooms 

 follow in succession, as shown in the figure : consequently, as the rooms advance to 

 the crop, additional rooms are begun at the dip-head level, towards c and D. Should 

 the coal work better in a level-course direction, then the level rooms are next the 

 dip-head level, and the other rooms follow in succession. Hence the rooms are 

 carried to the crop or rise in the one case, till the coal is cropped out, or is no 

 longer workable ; and in the other, they are extended as far as the extremity of the 

 dip-head level, which is finally cut off, either by a dyke or slip, or by the boundary of 

 the coal-field. 



Fig. 1-510 represents a part of a colliery laid out in four panels, according to the 

 improved method of the north of England. To render it as distinct as possible, 

 the line of the boards is at right angles with the dip-head level, or level course of 

 the coal. A is the engine-shaft, divided into three compartments, an engine-pit and 

 two coal-pits, like fig. 1493. One of the coal-pits is the down-cast, by which the atmo- 

 spheric air is drawn down to ventilate the works ; the other coal-pit is the up-cast 

 shaft, at whose bottom the furnace for rarefying the air is placed. B c, is the dip- 

 head level ; A E, the rise- or crop-gallery ; x, K, the panel-walls ; F, o, are two panels 

 completed as to the first work ; D, is a panel, with the rooms a, a, a, in regular pro- 

 gress to the rise ; H, is a panel fully worked out, whence nearly all the coal has 

 been extracted : the loss amounting in general to no more than a tenth, instead of 

 a third, or even a half, by the old method. By this plan of Mr. Buddie's also, the 

 pillars of a panel may be worked out at any time most suitable for the economy of the 

 mining operation. 



In Mr. Buddie's system the pillars are very large, and the rooms or boards narrow ; 

 the pillars being in general 12 yards broad, and 24 yards long; the. boards 4 yards 

 wide ; and the walls or thirlings cut through the pillars from one board to another, 

 only 5 feet wide, for the purpose of ventilation. In the figure, the rooms are rep 

 sented as proceeding from the dip to the crop, and the panel-walls act as barrie 

 thrown round the area of the panel to prevent the weight of the superincumbent 

 strata from over-running the adjoining panels. Again, when the pillars of a panel 

 are to be worked, one range of pillars, as at i (in H), is first attacked ; and, as the 

 workmen cut away the furthest pillars, columns of prop-wood are erected betwixt the 



