the stall-man, who also draws them out, using a "dog" and chain (as previously described and shown in Fig. 163).

The pack-walls are added to every 5 feet. Where the roof is tender, a chock made of broken timber and set on small coal is put in. As shown in Fig. 225, a sheet is fixed at intervals extending from the face several feet back into the waste lying between any two of the packs, the object of which is to cause the air to travel back into the goaf. Safety lamps are used in the workings, the responsibility of examining which rests with the fireman, who superintends the stall-men, but does no timbering.

In that part of the main level now being carried in the gob, little timber is required, but in that section of it situated nearer the shaft where the pillars remain, there is great side pressure, necessitating much timber.

The sets put in consist of props 8 inches at top and 7 inches at bottom, 6 feet 6 inches long, notched with the Welsh notch (shown in Figs. 181 and 182) into an 8-inch collar, which is notched to receive the props. The sets of timber are placed from 3 to 4 feet apart. Over them, reaching from collar to collar

3-inch props are laid in the direction of the road and laggings are laid across these. Two men work together in main-road timbering, the notches having been cut before the timber is brought underground. In fixing the sets of timber, the men use an iron bar called a dog. It has prongs at both ends, and when one prop is put in place the dog is used to steady it. The other prop is then placed in its position and the collar put on. When the parts are nicely adjusted the whole is struck with a hammer. Many ingenious contrivances are practised at this colliery for repairing the sets of timber. One is a set of timber in the form of an upright "cocker," as shown in Fig. 226. The props are 5 feet 6 inches apart at the bottom, and 4 feet at the top, while the rise of the span is 8 inches. Again, where the Welsh timbering is broken, a diagonal strut is notched into the prop and the collar as shown in Fig. 227.

As a third instance of repairing, where collars have been notched into the coal without the use of upright props and afterwards broken or partly broken by the weight on them, a short strut is put up under the point of fracture and wedged tightly to the collar, as shown in Fig. 228. The roads are dusty, but as watering causes the floor to rise, it is not carried out.

The roof over the seam, although soft and loose, does not require a large quantity of timber.

At the Great Fenton Collieries, Stoke-upon-Trent, in North Staffordshire, the Great Row Coal Seam is worked on the Longwall system. It is the same seam as that worked at the Florence Colliery, last described. The colliery comprises four pits, two, named the Pender and the Bourne, having been in operation since 1876, working the Blackband Ironstone and the Great Row Coal Seam; the other

two, called the Homer and Sutherland, are sunk to the Ash Coal and Littlemine Ironstone. These two have been working since about 1880. The pits are about of a mile apart. The Pender Pit is 13 feet in diameter, the Bourne Pit 8 feet, both reaching the Great Row Coal Seam at a depth of 308 yards.

The ventilation is produced by a furnace in the Pender Pit, which is fitted with wire-rope guides, two ropes passing through the outside of each of the two cages. At meetings, there is a clearance of 15 inches between these cages. The Pender Pit winding engine has a 36-inch vertical cylinder, with a 6-foot stroke, and 20-foot drum. About 500 tons a day are landed.

The seam dips at an inclination of 1 in 10. A section of it is shown in Fig. 229. The 3 feet 6 inches of top coal is left for a roof in the roads. Immediately over it are 5 yards of moderately strong shale, above which again is a bed of coal 7 inches thick. Resting on this thin bed of coal is shale. This 7-inch bed of coal emits a large quantity of fire-damp. Forming the thill under the coal are 4 feet of hard "sagger," or fireclay, which rests on grey metal. In the Long

Fig. 229.--GREAT FENTON COLLIERIES, STOKE-UPON-TRENT. COCKERSPRAG, SPRAG, PROPS, AND CHOCKS AT A WORKING FACE IN THE GREAT ROW SEAM.

wall method here adopted, there are 100 yards between the gate-roads. A "Butty contracts to put the coal into the waggons on the surface for a certain rate per ton or per score. The proprietor supplies all labour and materials. In a face of 100 yards, there are 9 or 10 holers, 4 loaders, and 2 buttockers. The buttockers break out the coal for the loaders, removing the sprags from under the coal for the purpose. There are also four packers whose duty is to build the packs. Each butty has a man specially appointed to take charge of the timber. The duties of this man are to set the chocks and draw the timber out, but the holers set all the props necessary for their safety. The holers and packers work during the night, but the fillers work in the daytime from 6 A.M. to 3 P.M., while coal is being wound in the pit.

Explosives are used to break down the coal, but no shots are fired till after 10 o'clock P.M. Fig. 230 is a plan showing the method of building the packs, timbering, &c. The roads are made 9 feet wide, and have built on both sides of them a pack-wall 4 yards wide. There are, besides these, other packs built in the waste, parallel to the roads, these packs being also 4 yards wide and separated by 8 yards of space. There is no ripping in the roads, so that stones for all the packs have to be obtained from the waste. Before commencing to hole, the cockermegs, shown in Fig. 229, are placed all along the face. They consist of two 3-foot props, and an old 6-foot prop, the latter being held in a horizontal position against the middle of the coal by the former, which are slightly notched into the roof and floor. The holing is then begun and holed 5 feet in, and as the holing

advances along the face, sprags are placed under the coal every 6 feet as shown in Fig. 229, in addition to the cockermegs already fixed. The packs are kept up within 6 feet of the face, as required by the Special Rules in force, but interposed between the packs and the face, and placed parallel with it, are set two rows of 8-inch props, having 6-foot spaces between the props, the two rows being 4 feet 6 inches apart. The rails are laid along the face between these rows. Besides this double row of props, two rows of timbering are placed between the pack-walls in the waste, these being set 6 feet apart under the top coal. Each of these rows of timbering comprises three props and a chock. The collier shears the top coal which is supported by these props, then draws the timber out, allowing the top coal to fall. He next sets props with a lid and a sill on the rubbish (see Fig. 162), thus securing the roof from which he has just taken down the top coal, and he is Scale. 49% feet to 1 Inch

Fig. 230-GREAT FENTON COLLIERIES, STOKE-UPON-TRENT. PLAN OF LONGWALL FACE IN THE GREAT ROW COAL SEAM, SHOWING PROPS AND CHOCKS.

now able to work at that portion of the top coal remaining over the packs. To obtain this coal, he holes in on the 4-yard packs, for 2 yards on each side, thus allowing the coal to drop. All the coal over the packs is not got, but as much of it as it is prudent to take without running risk from the roof. The props set on the sills over the rubbish are now withdrawn with a dog and chain, by the man specially appointed for the purpose, the chocks preventing the breaking of the roof, which immediately follows, from reaching the face. The top coal is not taken down in the roads, nor from over the packs formed at the sides of the roads. See Fig. 230. In time, however, as the roof sinks, this top coal is ripped in an arched form, leaving a good road which requires little timbering.

There is nothing special at this colliery in the manner of timbering the main roads. Props 8 inches in diameter are used, having lids 6 inches by 5, and 2 feet 6 inches long. In some of the main roads 7-inch collars are notched into the coal on one side and supported by a short 3-foot prop resting on the coal at the other. The roads are dusty and are watered as they require it. The roof generally is very good and safe to work under, requiring little timber.

At the Cannock and Rugeley Colliery, Hednesford, South Staffordshire, the Deep Coal Seam is worked on the Longwall system. The colliery has been in

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operation since 1865, and in 1881 was working both the Shallow and Deep seams, the former being 22 yards above the latter. The Deep Seam is the lowest of the series in this district, and is only separated from the Silurian measures below by a distance of 46 yards. A peculiarity of the South Staffordshire coalfield is the fact that the Coal Measures repose on the Silurian Rocks, the Old Red Sandstone, the Carboniferous Slates, the Mountain Limestone and the Millstone Grit being absent. Another peculiarity which may here be mentioned is the existence of the "Ten-Yard," or Thick Coal Seam, which is 30 feet thick.

The Cannock and Rugeley Colliery consists of the Cannock Wood Pits and the Pool Pits, the two concerns being separated by a distance of about 1 miles. At the Pool Pits are two shafts, each 15 feet in diameter and having 70 yards of metal tubbing in it, preventing feeders of water equal to 3,000 gallons per minute finding their way into the shafts. The depth here to the Shallow and Deep seams is 326 yards and 348 yards respectively. Coals are wound in one shaft, 4 tubs, each holding 13 cwts., being placed in the cage each time of winding. The engines used for winding are a pair of horizontal high-pressure cylinders, 32 inches in diameter. As much as 1,051 tons of coal have been landed during a day of

Fig. 231.--CANNOCK WOOD COLLIERIES, Hednesford, SOUTH STAFFORDSHIRE. SECTION OF DEEP SEAM, AND MODE OF PROPPING AND SPRAGGING IN A WORKING FACE.

8 hours, but about 900 tons is the average daily output. A 40-foot Guibal fan, 12 feet wide, running 33 revolutions per minute, produces a current of 150,000 cubic feet per minute, with 15 inch water-gauge, at the other, or upcast shaft.

The Cannock Wood pits comprise 3 shafts, 2 of which, 12 feet in diameter, are downcasts, the other, 16 feet in diameter, the upcast. The 3 shafts, after passing through the Shallow Seam at a depth of 178 yards, reach the Deep Seam 200 yards from the surface. The two downcasts are used to wind coal, 800 tons being landed in a day of 8 hours. Two tubs, each holding 13 cwts., are placed in the cage to be wound at one time. All coal is hand-picked, for which purpose the trams are run alongside the waggons, where the coal is sorted into 7 different qualities. Some 50 men on the pit-head sort and place 800 tons daily into the waggons. The sorting is let by contract, the price paid being 3d. per ton. A Guibal fan 40 feet in diameter and 12 feet wide produces the ventilation. The fan has 2 engines, each having a 36-inch cylinder with a 36-inch stroke, and working the fan alternately for a month at a time. The fan runs 36 revolutions per minute, exhausting 180,000 cubic feet of air per minute, with a 15-inch water gauge. The colliers use the Williamson Safety Lamp. A borehole 30 feet in the coal of the Deep Seam showed a pressure of gas of 35 lbs. to the square inch.

The Cannock Wood pits are situated on an anticlinal axis, the coal dipping on either side of the shafts at an inclination of from 1 in 24 to 1 in 18. The Shallow and the Deep Seams are both worked by the Longwall system. The practice is to keep the workings of the lower seam 300 yards in advance of those in the upper. This plan is found to work better than either advancing them together or keeping the upper seam workings in front of the lower.

Fig. 231 shows a section of the Deep Coal Seam at Cannock Wood, and the mode of timbering at the face there. The coal is 6 feet 7 inches thick. Immediately over the coal are 3 inches of black bat, then 18 feet 6 inches of dark shale with thin ironstone in it, above the shale being 21 feet of white rock. Under the coal is fireclay.

Fig. 232 shows the method of working adopted. The gate-roads are from 30 to 35 yards apart, cross-roads cutting them off every 100 yards.

Fig. 232.-PLAN SHOWING LONGWALL METHOD OF WORKING THE DEEP COAL SEAM AT THE

Fig. 233 is an enlarged plan showing two gate-roads, with the manner of building the packs, and setting the timber. On each side of the roads the packs are built 8 yards wide. Next these packs are 5 yards of vacant waste, then built parallel to the roads is a central pack 6 yards wide. The road is carried 11 feet wide, having a plate at the road-head, and the rails laid along the face.

Besides the Special Rules in force in the district, regulations are issued by the manager, stating distinctly the distance props are to be set apart, as follow:"The distance for props to be apart on the face must not exceed 3 feet, and each prop must have a suitable lid on it. The distance between the props for a tram

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