The stables at Eppleton Pit are most elaborate. Each pony stands in a distinct arch, 5 feet 6 inches wide by 6 feet long, the brickwork between each stall being 18 inches thick. A passage is provided behind the mangers with communications to each stall, through which the horse's food is introduced, thereby not only facilitating the work, but removing all source of danger to the attendant through the kicking

of the horses. The floors are laid with blocks cast out of furnace slag, on such an inclination that sock readily drains away, a gutter for this purpose being placed in the centre of each stall, which in its turn passes into the main channel running down into the central arch, out of which the stalls branch on either side. The mangers are also constructed of specially shaped bricks. Water troughs are not provided in each stall, but a large one is placed in the main arch near the entrance. The ponies dink on their entry to and exit from the stables.

At

Cost of Horse Haulage.-Given a considerable output and long life, there can be no doubt of the economy of mechanical haulage, but the saving is not so apparent if limited quantities are dealt with. small collieries, the capital outlay with interest and upkeep is so large and the quantity dealt with so small, that horse haulage compares most favourably with mechanical means, especially where the gradients are in favour of the load. An instance of this is given by Mr. H. F. Bulman* where the cost of leading 4407 tons an average distance of 1870 yards was 47d. per ton, or 4'4d. per ton per mile.

Upon the relationship of gradient to load the success or otherwise of horse haulage entirely depends. On level roads, or where the inclination is slightly out-bye, the amount of useful work performed by a horse is in strange contrast to that where the conditions are reversed, and the gradient is against the load. Lye Cross Pit supplies a very good instance of this. One stage measures 125 yards long, the first 35 yards being practically level, the remaining 90 rise outbye at an inclination of 1 in 12. Two horses are employed to haul coal this distance, each one making 42 journeys a day, a total distance travelled of 5.96 miles. The load of coals taken each time is one ton; the useful effect of each horse for this stage is, therefore, one ton led 2.98 miles-i.e., half the distance travelled. The stage immediately succeeding the foregoing one is 200 yards long, and practically level. *Brit. Soc. Min. Stud., xi., 176.

One horse serves this distance, making 21 journeys per day, travelling 477 miles. The load of coal is 4 tons, so that the useful effect is 4 tons led 2.38 miles, or 9:52 tons led 1 mile. A better illustration is afforded by another stage, where a horse makes 38 journeys per day, travels 4'75 miles, the load of each full set being 7 tons. The useful effect is therefore 7 tons led 2:37 miles, or 16.59 tons led 1 mile. The road had a slight gradient in favour of the load. At this pit, when the average distance each ton was led by horses was 480 3 yards, the cost per ton was 4.195d., equal to a cost per ton per mile of 15·37d.; when the average distance was 7747 yards the cost per ton per mile was 11.25d.

At Cwmaman Colliery* on a total of 12,615 tons, the absolute cost varied from 4'9d. to 6'4d. per ton, equal to an average over the whole pit of 16 2d. per ton per mile.

Messrs. Forster and Simpson † have taken out the costs of "putting" and "driving" at twelve collieries in the North of England, six worked on the bord and pillar system, and six on the longwall method, and with a fair proportion of thick and thin seanis. "Putting" is understood to mean the conveyance of single tubs from the face to certain collecting points; and "driving," the haulage by a horse or large pony from such collecting points to the engine planes, the tubs in this case being drawn in small sets. In working out the costs, all maintenance (comprising feeding, attendance, shoeing, veterinary surgeon and harness), wages to putters and drivers, and interest and depreciation on capital, was taken into account. With putting, the average of the twelve cases gave 27 tons per day led 180 yards, by each pony, at a cost per ton of 1584d. for wages, o 5od. for maintenance, and o'068d. for interest, &c., total 2.152d. With driving, an average of 30 tons per day were led a distance of 423 yards at a cost per ton of 0.531d. for wages, o615d. for maintenance, and o087d. for interest, &c., total 1.233d. The average total cost of putting and driving an average distance of 603 yards, therefore worked out at 3.385d. per ton. These figures may be taken as representing the cost under the favourable conditions of easy gradients and good roads which exist in the Northern coalfield.

Not only is the useful effect reduced by adverse gradients, but the lives of the horses are considerably shortened; in a short space of time they become worthless, and the cost of up-keep is a serious matter. A little consideration will explain the reason why gradients have such influence in haulage on rails, far more so than in surface work with ordinary carts. With well lubricated bearings and wheels on rails, the resistance to motion is slight, and a horse easily moves heavy loads under favourable circumstances. Down-hill gradients are therefore favourable to a good performance of useful effect, but where the inclination is against the load, the small resistance is against large weights being moved, as the load has a greater tendency to run back than if the surface on which it rolls was rough like an ordinary road. In the former case, the friction is so small that the horse has practically to contend with the full weight of the load divided by the gradient, while in the latter, the greater friction reduces the strain. Mechanical haulage therefore becomes a necessity with heavy gradients, as even where these are in favour of the load, the strain of *So. Wales Inst., xx., 347. + Fed. Inst., xv., 137.

returning the empties becomes so great that the advantage gained with the load is nullified.

Semi-Portable Engines.-When the gradients are against the load, the employment of some form of engine power becomes essential. As the direction and length of the roadways are continually changing, and as the situations in which they have to work are confined, small and compact self-contained semi-portable engines are generally employed. They usually consist of a pair of short stroke engines, geared down, and driving one or two drums on the second motion shaft. The drums are provided with foot brakes, and can generally be thrown in and out of gear by clutches. As a rule, they are arranged so that they can be mounted on wheels of the same gauge as the colliery railroads to allow of their being run from point to point. The motive power is generally compressed air; steam is inadmissible, and electricity does not so conveniently lend itself to the continual starting, stopping, and reversing which must take place.

The use of such engines is far more general on the Continent than in Great Britain, especially in the working of the thicker seams, where the greater portion of the coal is got to the dip. These small winches pull the full tubs up from the workings on to the level, and also lower the tubs containing the gobbing material to the face.

At Llanbradach Colliery, Mr. Galloway used portable winches, and dispensed with horses altogether, when the cost, under by no means favourable conditions, amounted to 4.310d. per ton hauled an average distance of 581 yards. This cost included all wages underground, wear, and renewal of ropes, coal burnt beneath boilers on surface, stoker, engine-driver of air compressor, stores, oil, &c., and general repairs, but did not include interest on capital and amortization, which was given at £313 48. per annum. *

SELF-ACTING INCLINES.-With mines having the necessary inclination, gravity supplies the motive power for the haulage, and self-acting inclines, or jig brows, are employed, the principle of which is that the loaded tubs running down-hill will haul the empty tubs up. A certain gradient is necessary, as the weight of the full set has to overcome the friction of the two sets, the drum and rollers, plus the weight of the empty set and rope; the latter is variable and greatest at the start. Roughly speaking, a gradient of 1 in 36 is required with wheels and axles of ordinary size; but the length of the road plays an important part, owing to the greater weight of the rope, therefore, as the plane gets longer, the gradient must also increase, to overcome the increased resistance. A flat part has to be provided, both at the top and the bottom, to make up the sets, and it is advisable that the gradient at the top of the incline should be greater than it is at the bottom, as the set then easily gets into motion.

Arrangement of Rails.-Nothing gives better results than two lines of rails completely from the top to the bottom, which is only possible when the roof is sufficiently good to allow of a double way being kept. If it will not stand such a width, three rails are carried from the top and bottom, with four in the middle where the tubs pass each other. These are the common arrangements, but rails may be arranged in many different ways.

Where the roof is so bad that a double road cannot be made, even

* Fed. Inst., xii., 273.

in the middle, two lines of rails are used, one inside the other. The tubs run on the outer line, and haul up a dead weight travelling on the inner gauge. At the point of meeting, the rails of the outer gauge are raised up and those of the inner depressed, and the dead weight passes underneath the tubs.

The weight of the balance must be less than that of the full set, but more than that of the empty one. The working capacity of such an arrangement is one-half that of a road laid with a double line of rails. For inclines where intermediate landings are worked, this arrangement gives excellent results, and in many cases, under such conditions, as much mineral can be jigged down with this system as by any

other.

Fig. 286.

In stall roads going into the working place, the common practice in steep mines is to make a full set going down one road haul up the empty set in the next adjoining roadway. (above 35°) the tubs have to be placed on special carriages (Fig. 286) to throw the coal into a horizontal position. If this were not done the load would be emptied as it passed down the incline.

Where the inclination is great

Rail.

Fig. 287.

Blocks or Stops.-Arrangements are always made at the top of inclines to prevent the tubs prematurely running down before the set is made up. The common form of blocks is shown in Fig. 287, but where the inclination is steep, the top part, a, is stretched across the whole width of the rails, and the two wheels of the tub rest against it. A much stronger construction is necessary where the tubs are gathered together to form sets, as severe blows are often delivered which the ordinary stop is incapable of withstanding. In such cases the block illustrated in Fig. 288 is employed at Lye Cross Pit, where there is a double road, but only half the arrangement is needed for a single way. Two round bars of iron, a a', are pivoted at b b', and when shut are held in the jaws, c c', which, in their turn, can describe the arc of a circle about the centres, d d'. The stops, a a', are fixed at such a height that the wheels (h) of a tub cannot jump over them. The blocks are opened by moving the jaw, c, about its centre, when the weight of the tubs pushes the bar right over. The jaws are kept at the proper level to receive the bar when it is brought back by a stirrup of iron, e, and in order that the bar may slide into the jaws, and not hang below them, two short pieces of rail, not shown in the figure, are set in the middle of the way on a slight inclination, so that the bar may ride easily on them. The bars have to be brought back into position, and closed on the jaws, after the tubs have passed, which a man easily does with his foot. The whole of the ironwork is firmly bolted to strong pieces of timber framed together. If the sets are

always jigged on the same side a balance block can be used (see Fig. 309). Mr. A. R. Sawyer describes a good block arrangement which

*

is opened and shut by hand at a distance, the working of which will be easily understood from Figs. 289 and 290.

Drums and Pulleys.-In permanent situations, and on long inclines, drums similar to those on winding engines are fastened on a shaft, the empty rope coiling on one, and the full rope on the other. A brake has to be provided to retard the descent, and to keep the velocity from getting too great. These drums occupy a considerabie * Miscellaneous Accidents in Mines, 1889, 153.