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continued parallel with the main level as soon as there is room enough to give 5 yards of coal on the rise side. This cross-cut (not shown in Fig. 251) is ripped and packed precisely the same as the levels. Its chief use is as an intake for the air going inbye.

Two colliers work in one place. The air, after circulating round the face, passes into a higher district or by a cross-measure drift or branch into the overlying seam, called the Thorofare, on which, the roof being excellent, the returns are carried.

The Upper and Little Toad Veins are worked in a manner similar, differing chiefly in the length the hatchens are carried, which are 80 yards in the former, and 60 yards in the latter seam.

The roof of the Great Vein is so bad that the main roads are carried in the Little Toad Vein, and these roads are connected to the Great Vein workings by cross-measure drifts of 120 yards in length as occasion requires, the roads on the Great Vein being then abandoned and allowed to fall.

At the Allanshaw Colliery, Hamilton, Scotland, the Ell Coal Seam is worked by the Pillar and Stall or Stoop and Room" method.

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Fig. 252.-ALLANSHAW COLLIERY, HAMILTON, SCOTLAND. SECTION OF THE ELL COal Seam.

The colliery has been working since about 1876, and consists of an upcast and a downcast shaft, each being 234 yards deep to the Ell Coal Seam. The shafts are circular in form, although the usual practice in Scotland is to sink rectangular pits, and then to divide them into two compartments, one for each cage; or if a set of pumps is to be placed in the shaft, it would have three compartments, the additional one being for the pumps. The Allanshaw pits are each 13 feet 6 inches in diameter. In 1881 the downcast solely was used for winding, although a pair of horizontal, high-pressure winding engines, with 26-inch cylinders and 5-foot stroke, had been placed at each shaft. In 1890 each shaft was used for winding. Single-decked cages, each carrying one tub or hutch which holds a ton, are used.

A Guibal fan 20 feet in diameter and 5 feet wide, exhausts the air at the upcast, and runs 40 revolutions per minute. At this speed it gives 40,000 cubic feet per minute with 5-inch water-gauge. About 450 tons of coals are landed in a 10hour day.

Fig. 252 shows a section of the Ell Coal Seam. There are 7 feet of coal, which parts badly from roof and thill or pavement. Over the coal are 4 feet of indurated fireclay, above which are 20 feet of rock. The pavement is composed of fireclay 6 feet thick.

Fig. 253 shows the method of working. The pillars are 20 yards wide by 30 yards long. The openings round them are 9 feet wide the short way and 12 feet wide the long way. The short way of the pillar faces the cleavage or cleat. The seam lies very flat, the dip being 1 in 20 to the North.

In the solid workings on a 12-foot wide place, a row of props or trees is set up,

The collier puts up these

the props being 5 feet apart, on each side of the roadway. props, and he is obliged to place them so that they are not more than 5 feet apart, whether the roof is good or bad. The trees or props are 4 inches in diameter at the

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Fig. 253. ALLANSHAW COLLIERY, HAMILTON, SCOTLAND. PLAN SHOWING PILLAR AND STALL
METHOD OF WORKING THE ELL COAL SEAM.

thin end, and cost at the colliery 7s. 3d. for 100 lineal feet. Two men work together in one place. Their practice, after the coal is holed, is to shear down one side of the coal and put a shot in the other, blowing out the coal. Open lights are used in the solid workings, and the colliers fire their own shots. They receive a tonnage rate for large coal, and another for dross or small, which includes payment for the timbering.

In the broken mine, the pillars are worked off in lifts of 5 yards. Three men work together in a lift. They hew the coal, place it in the hutches, and set up all

the timber. The colliers working off the pillars, or "stooping," as it is called in Scotland, use "Scotch gauze" lamps, and no blasting is allowed. The rails are laid in the road to about 3 feet from the coal, and a row of props set 3 feet apart, between the rails and the coal. On the waste side of the road are placed rows of props 14 inches apart, and about 3 feet between the rows. These trees are 4 inches in diameter and have small lids, 6 inches square and 1 inch thick, over them. Three men draw the timber from a lift, one of whom must be the fireman. In compliance with the Special Rules, he draws the props in the afternoon when his examinations are completed. Two of the men strike out the trees by blows from a hammer, whilst the third removes them to a place of safety on a timber tub made for the purpose. In a lift containing 300 trees, it takes about 3 hours

to draw the timber.

At the Cowdenbeath Collieries, in Fifeshire, the Dunfermline Splint Coal Seam is worked on the Longwall system.

The collieries have been in operation since about 1851, the work at present being carried on at three shafts, the Nos. 3, 7, and 8. The last two are downcasts,

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Fig. 254.-COWDENBEATH COLLIERIES, SCOTLAND. SECTION OF THE DUNFERMLINE SPLINT COAL SEAM.

and the No. 3 an upcast. The upcast is of a mile distant from Nos. 7 and 8 which are within 120 yards of each other. All the pits are of a rectangular form; No. 7, being 17 feet x 10; No. 8, 14 feet x 6; and No. 3, 14 feet x 5. The No. 3 Pit is 216 yards deep to the Dunfermline Splint coal, whilst No. 7 Pit is 270 yards deep to the same seam; and No. 8 Pit is 180 yards deep to the Lochgelly Splint and Parrot Seam.

A Guibal fan, 24 feet in diameter and 8 feet broad, is placed at the upcast shaft. It is driven at 60 revolutions per minute, and gives 50,000 cubic feet of air with 13 inch water-gauge.

Heavy pumping machinery is erected at both Nos. 7 and 8 Pits. The No. 7 Pit pumping-engine raises 800 gallons of water per minute, and that at No. 8 Pit raises 600 gallons. All the shafts are used to wind coal in, the total landings being about 800 tons a day. In 1881 the following seams were worked at the No. 7 Pit: the Dunfermline Splint 4 feet 6 inches thick; Fivefeet, 4 feet 8 inches thick; Mynheer, 4 feet thick; and the Lochgelly Splint and Parrot Seam, 12 feet thick. The strata dip to the North at an inclination varying from 1 in 6 to 1 in 3.

Fig. 254 shows a section of the Dunfermline Splint Seam. There are 4 feet 10 inches of coal. Resting on it are 15 inches of "Cash," or soft shale, used by the colliers to hole in. Above this is the roof, composed of shale, which is 12 feet

thick, and over this is rock. The pavement is freestone, about 6 feet thick. The shale over the seam makes a bad roof.

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Fig. 255.-COWDENBEATH COLLIERIES, EAST SCOTLAND. PLAN SHOWING LONGWALL WORKING OF THE DUNFERMLINE SPLINT COAL SEAM.

Fig. 255 shows the method of working this seam.

The levels are driven on

end, or nearly parallel with the planes of cleavage, and the faces advance against the cleavage. The roads to the rise are driven at right angles to the levels, and they are turned every 14 yards from the level. Level roads cut off the rise roads every 60 yards.

The men draw the coals from the faces to the wheel-braes or inclines, thence they reach the shaft by self-acting incline planes. Cutchain inclines (fully described in Chapter IX. of this work) are used to let the coals down from the upper levels to the main wheelbraes.

Scale. 49% feet to 1 Inch.

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LINE OF DIP

It is found better in working the seam, to step the wall faces, keeping them 5 yards in advance of each other as shown in Figs. 255 and 256, on account of the heavy bad roof. The weight is thus confined to the limit of each wall, and the roof settles down more gradually than when a straight line of face is kept.

Fig. 256.-Cow DENBEATH COLLIERIES, EAST SCOTLAND.
PLAN SHOWING FACE OF LONGWALL WORKING IN THE
DUNFERMLINE SPLINT COAL SEAM.

Two men work in a place, and besides hewing the coal, they put up all props, chocks and build the packs. They send out about 5 tons in a day of 8 hours, and receive 2s. a ton on large or round coal. Powder is not used in working this seam. Under the direction of the fireman, the colliers set their props where they think they are most required, there being no specified distance between them. The roof is so bad that withdrawing the props is dangerous and

most of them are left in. The props are 3 inches in diameter, the lids over them being of broken props. The "cash" obtained in holing is used to build the packs, but it makes poor buildings, and, to strengthen the packs, chocks, 6 feet square, made of props and filled inside with rubbish, are placed on the sides of the roads, as shown in Fig. 256. When the roads are finished and abandoned, these chocks are taken out.

The fireman visits each place three times during his shift, and although he sets up no timber himself, directs the colliers to do so where he thinks they are necessary. The main roads are secured by props and sets of timber, or gears placed at no specified distance apart, but at distances considered necessary. The roof being bad makes the cost of timbering high. The cost per ton on round coal 5d., the price of pit timber at the colliery being 5s. per ioo lineal feet.

In the working of THIN SEAMS the most advantageous system is the Longwall, and an arrangement of roads should be designed to suit the inclination of the

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Fig. 257.-No. 1 MODE OF WORKING THIN COAL SEAMS IN NORTHERN FRANCE AND BELGIUM,
ADOPTED WHERE THE INCLINATION DOES NOT EXCEED THIRTY DEGREES,

seam or seams to be worked. The cost of working must of necessity be higher than in the case of thicker seams. Still, thin seams are successfully and remuneratively worked both in Great Britain and in other countries.

In Northern France and Belgium three different systems of working thin seams are employed.* No. 1 system, shown in Fig. 257, is an arrangement for seams in which the inclination does not exceed 30 degrees. Roads are carried to the full rise out of the chief level, the distance between these rise-roads being from 12 to 14 yards. The faces follow each other in step-like order, as shown on the drawing. At first the coal is taken down each of these rise-roads by means of a small self-acting inclined plane. When the faces have advanced a certain distance a new level is turned, which cuts off all the longer inclined planes, except one or two, which are retained as main roads. The lower level is at the same time advancing and opening out fresh ground, thus supplying more working faces. The main roads are ripped, and on the inclined planes tubs carrying 10 cwt. are used. A full description of the self-acting inclined plane in operation here is given in Chapter IX. of this work.

No. 2 system, shown in Fig. 258, is suitable for seams whose inclination ranges from 30 degrees to 60.

In this case, a succession of faces, in step-like order, are driven. These faces advance in the direction of the strike of the seam, not towards the rise, as in the No. 1 system. Where the seams are so highly inclined and the face advances to * See Transactions, North of England Institute of Mining Engineers, vol. xxvii., pp. 174-180.

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