Coal shed

“ It has been ascertained that some coal-seams must have originated from the deposition of drift-wood in the mud and ooze of the sea-bottom, while others undoubtedly arose from the decay and entombment of vegetation in swampy plains of the land. That the latter mode of formation has been the usual one in most of our coal-fields has been generally acknowledged since Sir William Logan's announcement that each coal-seam, for the most part, rests upon a bed of fire-clay, which, with its embedded roots, marks the site of an ancient soil. ”

“ When, however, the accumoulation of the vast quantity of vegetable matter necessary for the production of the Thick coal was nearly completed, a very partial and local subsidence took place in one or two localities, bending down the previously formed beds into a hollow or pool of water, sufficiently deep for 128 feet of shale and sandstone to be accumulated, and thus another level floor formed for the growth of the upper bed of coal, which grew partly on the shale and sandstone, and partly on the undepressed coal. ”

“ It is their duty to pick out the pieces of slate, stone, or bone, from the stream of coal which passes under them, and throw this refuse into a trough at the side of the shute, from which point it slides rapidly away. The coal as it comes from the mine is full of waste material, so that the boy who sits first or highest on the shute has no trouble in finding plenty to do, and, work as hard as he may, much of the unfit material must still escape him. ”

“ Wherever a coal-field now exists, there must formerly have been free access for a great river, or for a shallow sea, bearing sediment in the shape of sand and mud. When the coal-forest area became slowly depressed, the waters must have spread over it, and have deposited their burden upon the surface of the bed of coal, in the form of layers, which are now converted into shale, or sandstone. ”

“ When the plants and trees died, their remains fell to the ground of the forest, and these soon turned to a black, pasty, vegetable mass, the layer thus formed being regularly increased year by year by the continual accumulation of fresh carbonaceous matter. By this means a bed would be formed with regularity over a wide area; the coal would be almost free from an admixture of sandy or clayey sediment, and probably the rate of formation would be no more rapid in one part of the forest than another. Thus there would be everywhere uniformity of thickness. ”

“ There will be cracks in the roof, small pieces of slate will drop to the floor, the distance between floor and roof will grow perceptibly less, pillars will bulge in the middle and little fragments of coal not larger than peas will break from them with a crackling sound and fall to the floor, until a deposit of fine coal is thus formed at the base of each pillar in the infected district. ”

“ So, too, the enormous hills of anthracite-coal dirt, that in the coal regions of our State have for years borne silent but eloquent testimony to the crudity and wastefulness of our methods of mining coal, now bid fair soon to disappear beneath boilers supplied with ingenious dust-burning devices, or in the form of lumps of artificial fuel. ”

“ Any experienced miner can tell when the face of the breast is approaching the outcrop; the coal becomes softer, changes in color, breaks into smaller pieces, sometimes water runs down through. It is obviously unsafe to erect buildings on the line of this outcrop, or immediately inside of it, where the roof is thin. There is no assurance that the body of coal left will not slip down the breast; and the pillars of coal near the surface are so soft that any disturbance of this kind may cause them to give way and let down the entire thickness of strata above them. ”

“ The conditions favourable to the production of coal seem therefore to have been—forest growth in swampy ground about the mouths of rivers, and rapid oscillation of level, the coal produced during subsidence being covered up by the sediment brought down by the river forming beds of sand or clay, which, on re-elevation, formed the soil for fresh growths, the alternation being occasionally broken by the deposit of purely marine beds. We might therefore expect to find coal wherever strata of estuarine origin are developed in great mass. ”

“ As it is, we must cross on the surface from the outcrop to the place where the corresponding seam enters the earth. In the southern and eastern anthracite coal districts of Pennsylvania decapitation of folds to a point below the coal [30] measures is general; the coal seams dip into the earth with a very sharp pitch, and the coal basins are often very deep and very narrow, striking into the earth almost like a wedge. In the northern or Wyoming district decapitation is not so general, the angle of inclination of strata is mild, and the basins are wide and comparatively shallow. ”

“ These "coal-pipes" are much dreaded by our miners, for almost every year in the Bristol, Newcastle, and other coal-fields, they are the cause of fatal accidents. Each cylindrical cast of a tree, formed of solid sandstone, and increasing gradually in size towards the base, and being without branches, has its whole weight thrown downwards, and receives no support from the coating of friable coal which has replaced the bark. ”

“ And when we consider the thicknesses of sandstone and shale which intervene beneath the coal-seams, we can realise to a certain extent the vast lapses of years which must have taken place between the existence of each forest; so that although now an individual passing up a coal-mine shaft may rapidly pass through the remains of one forest after another, the rise of the strata above each forest-bed then was tremendously slow, and the period between the growth of each forest must represent the passing away of countless ages. ”

“ When, therefore, adjacent or underlying excavations cause earth movements in a neighbor's property, litigation is likely to ensue and the geologist is likely to be called in. The long-wall method of coal mining, extensively practiced in certain parts of the United States, is slowly withdrawing support from the ground overlying the coal seams, resulting in damages to surface structures and in some cases to overlying mineral deposits. ”

“ The forests of the coal swamps accumulated in their woody tissues the energy which they received from the sun in light and heat, and it is this solar energy long stored in coal seams which now forms the world’s chief source of power in manufacturing.
The western area. On the Great Plains beyond the Missouri River the Carboniferous strata pass under those of more recent systems. Where they reappear, as about dissected mountain axes or on stripped plateaus, they consist wholly of marine deposits and are devoid of coal. The rich coal fields of the West are of later date. ”

“ These facts prepare us for the statement, of the truth of which good proof can now be given, that the change in the grouping of the beds was originally much more complete, even within the limits of the coal-field, and that the beds of coal which, coming together in the southern part of the field, form the Thick coal, are the very same beds, or some of them, which are worked now at Essington and Wyrley, and are there all more or less separated from each other by interposed shales and sandstones, so as to make a total thickness of over 300 feet. ”

“ But the driving of the stalls themselves is a work involving no little waste of coal and insecurity to the colliers; the mass of coal of eight yards wide having to be undercut, or holed about a couple of yards in, a large amount of coal is cut up into slack by the "pike," or collier's pick, and the men are exposed to continual risk from falls of coal. As the various portions of the seam are successively "cut" at the side of the stall, and brought down, the colliers have to mount on heaps of slack or light wooden stages, and are necessarily exposed to still greater danger. ”

“ When the surface of the coal country is mountainous and intersected by deep ravines, as in South Wales, the mineral deposites are approached by holes driven into the sides of the hills; but the common access to them is by vertical shafts, or well-holes, from the bottoms of which horizontal roadways are extended in long and confined passages through the coal strata, to bring all that is hewn to the "pit's eye," or bottom of the shaft, for winding up. It is requisite to have more than one shaft in the same workings ”

“ And though erect stems do not exist in every coal-field, we seldom fail to detect the not less important occurrence of the fire-clays and hardened shales that support the coal-seams and prove by their embedded rootlets their identity with ancient soils. Thus we arrive at the inference that while in certain localities coal-seams have resulted from drifted vegetable matter, they have nevertheless for the most part been formed from plants that flourished where the collier now excavates, amid damp and dripping caverns, their carbonized remains. ”

“ Thus a core or pillar of hard sandstone would be formed, which might do to the collier of the future what they are too apt to do now in the Newcastle and Bristol collieries. For there, when the coal is worked out below, the sandstone stems—“coal-pipes” as the colliers call them—in the roof of the seam, having no branches, and nothing to hold them up but their friable bark of coal, are but too apt to drop out suddenly, killing or wounding the hapless men below. ”

“ In rich fields, there are from three to ten of these rich layers or beds of coal, one above another. It often happens that the thickest and best layer is the lowest, and when this is the case, it is usually mined first, regardless of the fact that some, and possibly all, of the higher beds are dislocated and broken or filled with deadly gases. Nearly all this loss could be avoided by simply mining the upper stratum first. ”

“ It may indeed be hard to see how a practical method for drawing on this vast reserve of heat can be devised, but it is at least conceivable that it may be rendered available when the coal and other more accessible sources have become exhausted, or even when their yield has considerably lessened.
The coal of England may last a century or two; the coal in other parts of the globe may supply our cellars for a few centuries more, but the exhaustion of this truly marvellous product is proceeding at an accelerated pace. ”

“ The most modern mines use fewer supporting pillars of coal, and these are of larger size, so that there is less danger of accidents. Wherever possible they use timbers of wood instead of these smaller pillars of coal. They also mine as near the top of the seam of coal as can be done safely, and so regulate the blasting that much less slack is made than by the heavy discharges. These changes in mining methods save a far larger proportion of coal, and also prevent many accidents, which are the most unfortunate feature of coal mining, and the one which should receive most careful consideration. ”

“ The price is advancing each year as the supply is getting scarcer and the wood brought from greater distances. There is no way by which coal or wood could be brought here from other places. The recent discovery of a deposit of coal in the Paloo region, two days’ journey from Harput, aroused hopes that this problem might be partially solved, but the coal has proved to be of inferior quality and hardly worth bringing here. ”

“ Much power will always be needed where no stream for power is available. But the lesson is plain that where water can be used it should be, both in order to save the coal and because it can be produced more cheaply. The 30,000,000 horse-power now available, if produced in our most modern electric plants, would require the burning of nearly 225,000,000 tons of coal, and if in the average plant run by steam-engines, more than 650,000,000 tons of coal, which is fifty per cent. more than all the coal that is now produced in this country. ”

“ Long-wall work is best suited for thin coals, and those having a good roof, i.e. one that gives way gradually and fills up the excavation made by removing the coal without scaling off suddenly and falling into the working faces, when practically the whole of the coal may be removed. Against these advantages must be placed the difficulties attending the maintenance of roads through the goaves, and in some cases the large proportion of slack to round or large coal obtained. ”

“ Coal seams crop up above the ground in many places, and wherever this is the case, large frame conservatories are built which are lighted, not from the roof, but by wide double windows reaching from the eaves to the ground, and heated by numerous stoves into which the coal just taken from the ground is thrown. ”

“ It is estimated that sixteen per cent. of the material which goes into the breaker to be prepared comes out as waste, and is sent to the refuse dump. It can readily be supposed, therefore, that in the course of a few years these waste heaps will grow to an enormous size; and as a matter of fact they do. The dirt or culm, which includes all material [190] finer than buckwheat coal, is usually dumped on a separate pile from the rock, slate, and bony coal, since it is not wholly without at least prospective value. ”

“ For the coal merchants it's the same as for the woodcutters, said the Engineer, they only cut the trees we tell them to cut, and in this way they don't damage the forest. The best thing is that most coal is obtained without cutting any trees. ”