The Subterranean World

by G. Hartwig

Several attempts have recently been made to diminish the dangers of blasting, by substituting gun-cotton or nitroglycerine for gunpowder; or by firing charges by means of the electric battery, but hitherto without much success.

An enormous quantity of gunpowder is consumed for blasting in many of the larger mines. In 1836, 64,000 pounds were used in the Consolidated Mines in Cornwall, and 90,100 pounds in the Fowey Consolidated Copper Mines. The total amount of gunpowder consumed in the Cornish and Devonian Mines in the year 1837 reached 300 tons, which cost 13,200l. This one item may serve to give some idea of the enormous working expenses of a large mining concern.

Sometimes the rock is so tenacious as to render boring too tedious and expensive an operation, and fire becomes necessary for subduing the solidity of the stone. In this manner the ancient mine of Rammelsberg, near Goslar, is forced to yield its treasures, and whole forests are annually consumed in order to loosen the hornstone and indestructible spar of its metalliferous veins. Every Saturday morning the fire is applied to the numerous piles of billets and faggots that have been distributed throughout the course of the week. Those in the upper floors of exploitation are first burned, in order that the inferior piles may not obstruct by their vitiated air the combustion of the former. Thus at four o’clock in the morning the fires are kindled in the upper ranges, and then from pile to pile the firemen descend towards the lower floor, which occupies them till three o’clock in the afternoon. The vaults of Rammelsberg now afford a truly magnificent spectacle. The rising flames, flickering against the walls of the vaults, and ascending in broad sheets towards their roof; the dense clouds of smoke rolling towards the air vents; the crackling of the wood; the loud detonations of the stones rent by the expansive force of heat from the primitive rock; the lurid glare of the conflagration; the naked workmen with their mighty stirring-poles, flitting like dark spirits before the blazing pile; the intense heat, and the air loaded to suffocation with sulphurous fumes,—all combine to produce a picture worthy of Dante’s ‘Inferno.’ During the Sunday the noxious vapours engendered by the conflagration have time to disperse; and on the Monday morning the workmen detach, with long forks of iron, the ores that have been loosened by the flames.

The ore being extracted from its bed, it becomes necessary to bring it to the light of day, an operation which is of course of the greatest importance, and not seldom requires the aid of complicated machinery, particularly in coal mines, where large masses have to be conveyed as economically and speedily as possible to the upper world.

A great improvement has been effected of late years in the facility of transporting minerals underground, by the introduction of small tramroads, and the saving of expense thus effected sometimes amounts to one-half the former cost. Many of our larger mines are provided with miles of this subterranean railroad, and the advantage is greater, because for the most part there is a slight descent from the workings to the bottom of the shaft, to allow of a more complete system of drainage than could otherwise be attained. But frequently where the galleries are low, narrow, and crooked, the carriage is still effected by means of sledges, barrows, or little waggons, which are with difficulty dragged or pushed along, over planks or uneven and muddy roads; and sometimes even the interior transport of the ore is executed on the backs of men—a most disadvantageous practice, which is gradually wearing out.

CONVEYANCE OF MINERALS UNDERGROUND.

In great mines, such as the coal and salt mines of Great Britain, the salt mines of Wielitzka, the copper mines of Fahlun, the lead mines of Alston Moor, horses have long been introduced into the workings, to drag heavier waggons, or a train of waggons attached to one another. In some cases these animals are brought to the surface at stated intervals, but generally when once let down the pit they for ever bid adieu to the light of day. Strange to say, this unnatural mode of existence, which would soon undermine the vigour and spirits of man, agrees admirably well with their health, of which the greatest care is taken, as their useful services are duly appreciated by their owners. They are abundantly fed with hay and oats of the best quality; their stalls are large and well ventilated; and as they labour in a mild and equable temperature, they remain free from many complaints to which horses are liable. Their good condition and sleek, shining coats prove that they have no sentimental longing for green fields or the bright sunshine. In a few of the largest collieries it has been found advantageous to establish underground stationary engines, which bring the trains of waggons, by means of an endless rope, along the galleries to the bottom of the shaft. In other mines, such as those of Worsley in Lancashire, subterranean canals are cut, upon which the mineral is transported in boats.

In the European mines, the ores are usually lifted from the bottom of the shaft to the surface by steam-power, or horse-gins; but in Spanish America, men, and even women, are employed for this purpose. The steep ladders which they ascend with heavy weights upon their backs, consist merely of the thick trunks of fir-trees, into which, at intervals of every ten or eleven inches, deep notches have been cut; but these rude steps are mounted with perfect security and ease by the sure-footed Indians.

In many European mines, where the workmen are let down or raised by means of ropes, wire cables, or chains, they sometimes sit on transverse round pieces of wood or in a kind of chair, consisting of two strong leather belts, one of which serves as a seat, and the other for supporting the back. In Wielitzka ten of these chairs are attached to the cable at distances of seven or eight feet one from another. The persons seated in the uppermost and lowest chairs direct the descent, and take great care to prevent the conveyance grazing against the sides of the shaft, for were it to be hooked fast by a nail or any other projection, a fall into a deep precipice of several hundred feet would be the almost inevitable and fatal consequence. The old method of descending into a colliery was by a corf or strong basket, hooked on by a chain to the rope that hung down the shaft. Stepping into this, the men would swing down the dark hollow, gaily and readily, but not always safely.