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thin. They are wide enough, stretching under a large tract of country, but are often only a few inches deep and (with a single exception) never more than six or eight feet. There is a seam in Staffordshire thirty feet in thickness. The beds of grit and shale between the coal seams are a great deal thicker than the coal itself; many different seams of coal, however, lie, one under another, at the same spot.
The great northern coal-field of Northumberland and Durham supplies London, and all the east and south coast towns with coal, as well as a good deal of the continent. It reaches from the Tees to the Coquet; there it ceases, and re-appears further north, having a length of eighty miles in all, and a breadth of from ten to twenty.
Bishop Auckland, Brancepeth, Durham, and Chester10-Street are the centres of the coal-mining in Durham, and they all have mining villages round them.
Newcastle, Warkworth, Morpeth, Throckley, Wallsend, whence the famous Wallsend coal comes, Hartley, Willington, and many other villages and towns in Northumberland, are the homes of the pitmen who work in the neighbouring mines. From the Tweed to the Tyne, the coal extends along the coast, and even dips below the German Ocean ; the miners at work in some of these pits may hear the sea rolling over-head.
GEOLOGISTS can tell, by the sort of rock which appears at the surface, whether coal is likely to be found underground.
Let us suppose a Coal Master is going to open a new pit: he chooses a likely spot for coal, but at present, perhaps, sees nothing but a grass field or a furzy common.
The first thing to be done is to bore a hole deep down into the earth, with a sort of chisel at the end of an iron rod; as the hole is not large enough for a man to follow the chisel, it is driven by a machine. If the boring tool passes through many coal seams, the Coal Master knows that he has found the right place for
Then a shaft is sunk; that is, a hole deep enough to reach a good thick coal seam, and wide enough to allow men and horses and carts to be lowered to the coal. The shaft is a round opening, which is sometimes carried down to a depth of five hundred yards before it touches a coal seam.
When they reach a good seam, the miners drive a broad passage through it, from top to bottom, from roof to floor. This is called the mother-gate: gate is the north-country word for a road or way; and this is the mother-gate because many passages are driven from it on either side. When all the gates have been driven, the coal-mine is a little like a town with many streets, some wide, and some narrow, with great pillars of coal here and there, like buildings.
The men who hew the coal are lowered into this underground town, where the darkness is so black, that it would make the darkest night seem bright; and all the light they have is from the little candle or lamp which each man carries in his hat. Every man has his own place in the mine, and each sets to work with his pick to hew out the walls of coal. The coal is thrown into baskets, or into trucks, which horses draw
along tramways to the great shaft: there it is put into wagons, and these are raised to the surface by an engine. Large underground stables are often to be seen in a coal-pit.
The collier often works in galleries so low and narrow that he cannot stand upright, or even sit. He labours in a stooping posture, sometimes lying on his side, for-save for a short interval--eight or ten hours together. His work is done by the glimmer of a small candle, five or six hundred yards down in the bowels of the earth. Often he must make his way through two or three miles of underground passages to get to his work.
Nor is this all; the roof of his gloomy workshop may break in and crush him; and often does so when he is careless and does not put in a prop of wood from time to time to uphold it. Then again, the earth's crust is always more or less full of water, and, though engines are kept at work, pumping, to keep the pits dry, a sudden rush of water may burst in at any time, fill the galleries, and drown the hewers. The air, too, is close and bad in these deep pits; often bad enough to poison a man, though great pains are taken to make a constant draught through the mine.
There is another more terrible danger. A great fire may break out suddenly and fill the pit with death, and, in the most fearful manner, the miner may be scorched and shrivelled to a blackened mass, shattered to pieces against the sides of the mine.
We all know that the gas with which our houses are lighted is made from coal, and that, if this gas
be allowed to escape so as to fill a room, a lighted candle taken into such a room would cause an explosion.
Coal, especially Newcastle coal, gives off a great deal
THE STORY OF A PIECE OF COAL.
of this inflammable gas in the pit. The gas
mixes with the air, and moves along with the current, or draught, of air towards the shaft. Every now and then, the collier lays open with his pick a hole in the coal which is quite full of this gas, or, as the workmen call it, fire-damp, which rushes out with a blowing noise.
If a hewer with his lighted candle come in the way of such a blower sending out a torrent of gas,
gas blazes up, the flame spreads like lightning to other gas all over the mine, and, battered by the explosion, and shrivelled in the fierce heat, horses and men come to a terrible end.
The only way of preventing these disasters seems to be to keep the mines well ventilated; that is to say, to keep the air that is in a mine always moving towards one shaft, and to get in a supply of fresh air by another. In this way, the fire-damp, instead of lodging in holes and corners about the roof, is swept out through the mine, and goes up the shaft as up a chimney.
THE STORY OF A PIECE OF COAL.*
Many long ages ago, this piece of coal was part of a waving forest of tree-ferns and gigantic club-mosses. The climate of England was very different then from what it is now-never too hot nor too cold, and very soft and balmy.
This great forest grew by the seaside, and the land was slowly, slowly sinking. Every now and then the
* Adapted from Dr. Taylor's 'Geological Stories.'
tide came in among the trees and went out again, leaving much sand behind. In fact, many of the forests were actually buried thus, and their strong trunks are now met with, standing upright, in solid sandstone rock.
After a forest had been buried in this way, other trees could not grow very well on sandbanks; but as ages went on, soil gathered on the sand, and another forest grew in the place of the first, to be buried up
in its turn.
During countless ages, this growth and covering up went on, until, in some places, as in the South Wales coal-field, there are no fewer than one hundred different seams of coal, under each of which you may see a clay full of the roots of those ancient forests.
After the trees had been long buried and pressed down in the depths of the earth, changes began to take place. The mass heated, and turned black, just as a stack of hay does when it has been packed in a damp state. By-and-by, it was changed into a sort of pulp, so that you could not tell leaves from branches; and, at last, it became hard, and black, and bright—the very coal you
all know so well. These ancient forests grew by means of the ligḥt and heat of the sun, so that a piece of coal is really so much fossil sunshine! And when you warm yourselves by the fire, you are really enjoying the heat of the sun, which was poured down on some forest of those old, old days, and was stored away by its leaves.
Map Questions. 1. What sea washes these counties? On which side? What islands lie off the coast? To what countries do the opposite shores of this sea belong?
2. Name in order the rivers which flow into this sea? Which of