Mining is the term applied to the underground engineering process by which minerals are excavated and brought to the earth's surface. That this process in a crude form was known to the ancients is shown by references in the book of Job, the records of the Phoenicians and Egyptians, and the signs of supposed Roman excavations found in Britain. The first important historical record of mining operations in England is found in the charter to dig for coals, granted in 1259 by Henry III to the freemen of Newcastle-on-Tyne. Then, again, in the reign of Henry VII a commission was empowered to dig and search for metals; while during Elizabeth I's reign German miners were induced to visit England, and extensive privileges granted to the 'Society of Mines Royal.' Begun thus early, the development of mining has been greatly advanced by the introduction of gunpowder and other explosives for blasting; by the use of steam-engines for pumping water from the mine and bringing material to the surface; by improved ventilation, which enables mines to be carried to deeper levels; by the use of electricity, etc.
Metalliferous mining (mining for metals) has to deal with a mineral which is found in lodes or veins irregularly imbedded in rock-fissures, the trend of which is uncertain and the thickness variable. In preparing to excavate this irregularly distributed mineral two shafts are sunk in the vicinity of the lodes, one of which is used for pumping and ventilating the mine, the other for drawing the material to the surface. From these two shafts horizontal galleries are driven at distances of 10 or more fathoms apart, an additional gallery being driven at intervals of 10 or 15 fathoms as the mine is increased in depth. The galleries are driven as far as possible on the course of the lode, and if the lode is going down on a slope, the galleries in such case are not vertical above one another. These galleries are connected by vertical passages or 'winzes;' and in this way they are ventilated, and the material to be excavated is divided into rectangular blocks.
The metal ore after being excavated is broken up by the miner, put into a barrow, wheeled to one of the main galleries, thence transported in cars drawn on rails formerly by men, mules, or, and in modern times engines, to the main shaft. There it is hoisted to the surface in an iron 'kibble' or a wooden 'skip' which travels up and down in guides fixed to the side of the shaft. Access to many metalliferous mines was right up to at least the Great War obtained by means of ladders fixed almost vertically in the sides of the shaft. This toilsome method was averted in some mines by what was called a 'man-engine,' which consisted of two rods with platforms attached which moved up and down reciprocally the distance between two platforms, the miner ascending or descending from the platform of one rod to that of another alternately. Besides the shafts there is usually an entrance to the mine called an 'adit' or 'day-level' which is driven straight into the mine from the nearest convenient depression or valley and is mainly used for purposes of drainage. Adits are sometimes of great length.
Coal-mininy has to deal with a mineral which is deposited in scams or beds, sometimes nearly horizontal, at other times nearly vertical. These seams are interstratified with layers of sandstone, shale, clay, etc, and when the beds are tilted the coal has been frequently found outcropping at the surface. In the chief coal-fields of the United Kingdom this outcropcoal had been exhausted by the start of the 20th century, and it was then found necessary to approach the coal-seams by means of shafts, of a rectangular or circular shape, sunk into the earth. The rectangular shape, commonly 18 feet by 6 feet was that which was used most frequently in Scotland, while the circular shaft obtained in the large mines of Northumberland and Durham. Before sinking the shaft it was expedient to bore down through the strata in order to test the thickness and direction of the coal-measures. The bore-hole was usually begun by digging a small pit about 6 feet deep, and the old method was to pierce the rock by means of a cutting-tool attached to long rods and worked by a lever with hand-power. Various improvements on this slow method were made, as where hydraulic or steam power was used to drive the boring-rods, and diamond drills employed instead of the steel tool.
When this boring test had been found satisfactory the shaft was then sunk. One
shaft not infrequently intersecting a number of workable coal-seams, these being generally separated by shale, sandstone, and limestone. Seams of coal vary in thickness from 2 inches up to 30 feet as formerly found in Staffordshire, or even to 90 feet as once found in a small coal area at Johnstone, near Glasgow.
The coal having been reached, the mining engineer has to devise the safest and most economical method of cutting the coal and sending it to the surface. There are two commonly adopted methods of working out coal-seams: the 'pillar-and-stall' or 'stoop-and-room' system, and the 'longwall' or 'long-work' system. The former method consists in excavating 'rooms' in such a manner as to divide the coal into rectangular pillars or 'stoops.' In the early days of coal-mining the stalls were made large and the upholding pillars left small, no attempt being afterwards made to recover the coal in these pillars. When the floor of the mine was of soft clay or lime the weight of the roof drove the pillars down, causing the floor to rise in the centre between the pillars, and establishing an undulating movement throughout the underlying strata called by miners 'the creep'.'To prevent this the coal was left in wide barriers or 'pannels' which divide one part of the workings from another. The pillars of coal which were left were recovered by a second operation, which consisted in cutting them out after a division or pannel had been excavated to its boundary, or by working them out when the stalls had been driven the length of two or three pillars. These pillars were, in most cases, about 20 yards square, and in one pannel of the mine there were often 600 such pillars.
In the ' longwall' method the miner cuts into, or 'holes' into, the underpart of the coal-bed for two or three feet, and then, with the aid of wedges driven in atop, he loosens and extracts the mass of coal which has been 'holed.' By this system the entire coal-seam is at once extracted, while the empty space or 'goaf' is filled in with waste material as the work advances.
One of the most important matters connected with coal-mining is ventilation. To facilitate this there are two openings into the mine, which are technically called the 'intake ' and 'return' air-passages. The necessary supply of pure air is maintained either by the natural heat of the mine causing a constant inrush of cold air; by pumps or fans forcing the air down the 'downcast' shaft or drawing it up the 'upcast' shaft; or by furnace ventilation. This latter mode is considered the most efficient. The furnace by its heat causes a constant current up the upcast shaft, thus drawing the vitiated air away from the workings. Connected with ventilation is the dangerous accumulation of fire-damp which may take place in a mine, to guard against which safety-lamps were introduced.
The pumping of water out of the workings is also an essential part of mining. Research Mining
Nur and Spel was an old game played in Northern England. In Lincolnshire it was played with a 'kibble', a 'nur', and a 'spell'. By striking the end of the spell with the kibble, the nur, of course, rises into the air, and the art of the game was to strike it with the kibble before it fell to the ground. He who drives it the greatest distance wins the game.
Strutt describes this game as 'Northern-spell', played with a trap, and the ball is stricken with a bat or bludgeon. The contest between the players is simply who shall strike the ball to the greatest distance in a given number of strokes. The length of each stroke is measured before the ball is returned, by means of a cord made fast at one end near the trap, the other being stretched into the field by a person stationed there for that purpose, who adjusts it to the ball wherever it may lie. Research Nur and Spel
Abbreviations
Research Kibble
