MINE. 



355 



Ft ATE 



ircxcii 

 K.,.4. 



SlWTord- 



ttlMfot gtound-coal first, of from three to five feet thick, the 

 <^>1- _ length of the pillar and thirling, and then returning to 

 ^""""Y~"*" the fac?, work the upper part of the coal overhead. 



When the coal is free, and ready to crumble by the 

 pressure and effect of the air, the upper portion of the 

 coal is first wrought, then a scaffolding of coal is left, 

 from two to three feet thick, according to the texture 

 and quality of the coal ; and the lower part of the 

 coal is then wrought as represented in Fig. 4. Plate 

 CCCXCII. When the workings are completed to the 

 proposed extent, the scaffoldings of coal are wrought 

 way, with the part of the pillar* that can be removed 

 with safety. 



A* the using of propwood in coal of so great a height 

 i* not found practicable, and a* falls in the roof would 

 be so exceedingly fatal to the workmen, if the roof is 

 in the leas* decree tender, it is the practice in such 

 cases to leave a roof of coal from two to three feet in 

 thickness. This of it.-elf not only makes an excellent 

 roof, but when it is breaking, gives warning by the 

 noise it makes, so very different from the noise of roof- 

 stones when they are giving way. 



One of the thickest coals in Great Britain which ia 

 *j *** wrought as one bed from roof to pavement, i* the rery 

 remarkable coal in Stafford-hire, close to the town of 

 known by tlie name of the ten-yard coal, a 

 in of which, with the accompany ing strata, is given 

 in the preceding part of this treatise : thi* wonderful 

 bed of coal is in extent about seven miles long, and 

 four broad. No coal similar to it ha* been found in the 

 island, and the mode of working it is altogether singu- 

 lar. It i* wrought in a kind of pannel work, but al- 

 tngctlier different from the improved Newcastle sys- 

 Isjn. 



Numerous pit* are used in working a coal-field even 

 of moderate extent at Dudley : and in place of one pit 

 with one carve ascending and another descending al- 

 ternately, a* in other collieries, two pit* are always 

 sunk, from ten to thirty feet apart, and from MX to 

 seven feet diameter, of a round form : for these two 

 pits, one coal-drawing engine is employed, having a 

 rope into each pit, the object being to draw the coals 

 with a very slow motion, but a great weight of coals 

 each time. A funnel or compartment formed in work- 

 ing the coal, is named a side of work ; and in each 

 side of work sometimes only two pillars are formed. 

 In other cases there are four, six, nine, or twelve, but 

 the last number is very seldom adopted ; two or four 

 pillars in a side of work left for the support of Un- 

 roof is the common practice, and what is most ap- 

 proved of. As the whole operation of working tin- 

 coal is performed in one of the compartment*, named a 

 side of work, it will be proper to explain the mode of 

 working out the coal from one of these, before describ- 

 ing the whole extent of the workings of a pit. 

 PLATC 'iff. 1. Plate CCCXC1II. represent* a side of work ; 



A, the ribs or wall* of coal left around, and form- 

 ing the side of work; a the pillars, 8 yards square; c the 

 stalls, 1 1 yards in width ; d the cross openings or 

 through puts, also 1 1 yards wide; e the bolt-hole cut 

 through the rib from the main road, by which bolt- 

 hole the side of work is opened up, and all the coals 

 carried out. There are two, three, or four bolt-holea 

 opening into a side of work, according to its extent ; 

 they are about eight feet wide, and nine feet high. 

 A* the coal i divided into subordinate beds by com. 

 mon coal partings, or by bands of stone termed batt, 

 of from an inch to above a foot in thickness, though in 

 ome instances bands are many feet thick, the work- 



< rirm. 



ing i* in a great degree regulated by these divisions. Mines ot 

 Although the coal is 30 feet thick, the lower band, 

 which is 2 feet 3 inches thick, is wrought first, the 

 workmen choosing to confine themselves within this 

 narrow opening, in order to gain the greater advantage 

 afterwards in working the coal immediately above ; 

 as soon as the workmen cut through the bolt-hole, they 

 open up the work by cutting a mine forward, four feet 

 in width, as represented by the dotted lines. Attlte 

 sides of this mine, next the bolt-hole, each workman 

 in succession breaks off a breast of coal, two yards 

 broad, as ntff, by means of which the sides of the 

 rib-walls A, are formed, and the area of the pillars. In 

 this manner each collier follows another, as in one 

 of the systems of the Shropshire method before de- 

 scribed. When the side of work is opened out along 

 the rib-wall*, and the faces and sides of the pillars 

 formed off, the upper coals are then begun to be 

 wrought next the rib-wall, which is done by shearing 

 up to a bed .next the bolt-hole, and on each side, 

 then the head coals arc brought regularly down in 

 large tabular masses, of such thickness as suits best 

 with the free partings or subordinate divisions of the 

 coals and bands, the shearings are made very wide 

 when they require to be put up five or six feet, as in 

 this case they must admit the head and shoulders of 

 the miner. For the security of the workmen, props of 

 wood are used to support the first of the upper coals, 

 and temporary pillars of stone are also built at conve- 

 nient distances ; these are termed cogs. Besides the? e 

 safeguards, if the mass of coal to be brought down i 

 great, square spurs or spurns of coal are left, about 10 

 inches thick at the lower part of the shearing, and at 

 various distances, until the shearing is completed ; 

 the props and cogs are then withdrawn, the Kick 

 spurns are cut awr.y in succession, until the front 

 ones are also cut away, then the cogs and props at 

 the lip of the hanging coal are driven out, \vhen the 

 coal falls in a body, breaking off by the ends of the 

 shearing. Boides the main pillars represented in the 

 figure, temporary and intermediate pillars are formed, 

 of from two to three yards square; these are tcr 

 mt o/'unr. In the fir*t workings of the 10 yard > 

 the*e temporary pillars were formed when carrying 

 forward the work in the coal next the pavement," but 

 this was found not only a hindrance in carrying for- 

 ward the work in the first opening, but as the sides 

 of work were extended, a certain degree of pressure 

 came upon the work, when these pillars, or men of war 

 instantly gave way and were of no use. Experience 

 ha* taught the miners a remedy for this, which is, to 

 form none of these pillars until the first of the upper 

 coal* begins to be wrought, when square basement* of 

 stone are formed on the pavement at the places where 

 the men of war are to be, of an area some inches or a 

 foot larger than the intended size of the pillar ; and 

 when the building is within three or four inches of 

 the coal, that space is filled up with pieces of wood, 

 mode moderately firm ; the effect of this is, that when 

 the pressure of the superincumbent strata begins to 

 bear upon the whole of the pillars, the pieces of wood 

 and under-building yield by degrees, and prevent the 

 pillar of coal above from giving way. This principle 

 is found effectual, and could only have been discover- 

 ed in the course of much previous practice ; it is a 

 principle which is applicable in many instances to 

 mining operations, when a degree of yielding to the 

 pressure is more efficient as to ultimate reirtance, 

 than a rigid resistance at once applied. In this man- 



