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sages are cut in
of coal, and are a natural result of the mode of working the coal. If the whole of a seam of coal were worked
away at once, the cavity left would be so large that the earthen roof, failing of support, would fall, burying all beneath it. There are portions left, therefore, called “pillars," to support the roof; and the self-interest of the coal-owner leads him to limit the size of these pillars as much as is consistent with safety. Passages lead between and around and among these pillars; and iron tramways are laid along the passages, to make it easy to move the tubs of coal from the workings to the shaft.
With regard to working the coal, the pitmen are obliged to adopt different methods according to the thickness of the seam. In ordinary cases the hewer cuts with his pick a horizontal line at the bottom of the seam, to an extent of twelve or eighteen inches in front of him, and to this extent the coal is severed from the ground beneath. He then makes a few cuts upwards, to isolate the coal into huge blocks, which still adhere at the back and top to the general mass. The driving in of a few weages, or the application of gunpowder as a blast, soon brings down these blocks, in a more or less broken state.
The seams of coal, and the apertures where such seams have been, often give out gases which, when mixed with common air, become very explosive. Hence, it is important to drive these gases out of the mine as quickly as possible, and
this can only be effected by sending a constant current of air through the working. A complete system, as now adopted at the best collieries, comprises the downcast-shaft, for the descent of fresh air; the upcast-shaft, for the ascent of vitiated air ; well-planned galleries, doors, and valves throughout the whole of the mine ; and a furnace at the bottom of the upcast-shaft to heat the ascending air, and make it ascend more rapidly. In some collieries the air is made to traverse an extent of thirty miles of galleries and passages. In former times, the dangerous contan.inated passages were lighted only by sparks struck from a small instrument called a "steel mill,” but the beautiful safety-lamp, or “ Davy,” as the miners familiarly term it, has superseded this. In this lamp there is a lamp-flame surrounded by a wire-gauze having very fine meshes, through which the air must pass to feed the flame; if the air be inflammable, the flame is confined within the gauze envelope. If the lamp be properly tended, it is one of the most precious boons that science ever gave to industry; if it be neglected, as it often is by the miners, those explosions take place which so frequently give rise to such fearful results.
The hewer is the actual coal-digger. Whether the seam be so narrow that he can hardly creep into it on hands and knees, or whether it be tall enough to stand upright in, he is the responsible workman who loosens the coal from its bed.
The putter drags the coal from the working to the passages, where horses are able to be employed in the work. The crane-man manages the crane by which the great baskets of coal are transferred to the waggons.
The viewer is the officer who is responsible for the work, and so on ; for as the reader has here means of observing, the colliers are not merely blackened - faced diggers and shovellers, who attack the coal wherever they meet with it, and roam about in a dark pit to seek their coaly fortunes. All is pre-arranged and systematic; every one knows exactly whither he is to go, and what he is to do.
" The Land we Live in."
The means employed by Nature, the great planter, to effect the dispersion of seeds, and by which the young plants are separated and sent out into the world from their seed-cup homes, are as various and curious as the forms of the seed-cups themselves.
as the seed is ripe," Gerard quaintly remarks, “ Nature taketh several methods for its being duly sown. For first, the seeds of many plants which like a particular soil or situation are heavy and small enough, without further care, to fall down directly
6 So soon
into the ground. But if they are so large and light as to be exposed to the wind, they are often furnished with one or more hooks to stay them from straying too far from their proper place. On the contrary, many seeds are furnished with wings or feathers, partly with the help of the wind 'to carry them when ripe off the plant, as of ash, sycamore, maple, mahogany, and trumpet-flower, and partly to enable them to make good their flight more or less abroad, so that they may not, by falling together, come up too thick, and that if one should miss a good soil or bed, another
hit. So the kernels of the pine have wings, yet short, whereby they fly, not into the air, but only flutter upon the ground. But those of the dandelion, and most of the thistle kind, have long, numerous feathers, by which they are wafted every way.
Other seeds are scattered, not by flying about, but by being spurted, or darted away by the plant itself. The wood-sorrel has its seed-vessel constructed in such a way, that when dry it bursts open, and in a moment is violently turned inside out. When oats are ripe, the grains are thrown from the flower-cup with a crackling noise, which may be heard in passing near an oat-field on a fine day. If the touch-me-not balsam is touched, it instantly fires a discharge of seeds at the intruder. Spencer Thomson, in his book on “Wild Flowers," says many must have remarked this fact about various seeds themselves, when, under the heat of a July sun, their wanderings have led them through
Path with tangling furze o’errun,
When bursting seed-bells crackle in the sun, and they have wondered what could be the meaning of the incessant crack, crack, which seems momentarily to occur on every side, as if some fairy-folk were firing off little guns to celebrate the fine weather. At last the eye detects one of the black pods of the broom in the very act of firing; in one moment each pod-valve has twisted itself into a spiral, and sent its seeds flying all around.
Nature has several other methods of planting. The screw-like appendages of the crane's seeds assist them to roll into some chink in the earth, and then screw them into it. The poppy has little pores at the summit of the seed-cup; and the pimpernel splits off a little lid, and discloses its well-hoarded treasury, while the cross-flowers, like the wall-flower, quietly lift up their sides to let the seeds fall. The willow herb opens elegantly at the top to let its beautifully arranged and winged germs take flight. The ivyleaved toad-flax carefully buries its seed. The mignonette seed escapes easily by the little bell in which it is contained, opening and permitting it to fall as soon as perfected.
Nature has ensured the preservation of many vegetable species by the truly astonishing number of seeds she produces. It has been calculated that there are about thirty thousand seeds in every