CHAPTER XLII.

BELOW THE SURFACE.

In order that the reader may get a proper idea of the underground works of a mine, I shall now give a detailed description of all that is worthy of special mention. Drifts are openings or galleries from four to six feet in width, and from six to eight feet in height, opened along the course of the vein. They are generally run along one of the walls of the vein, in the “country rock,” (rock outside of the vein) as that contains no lime, and therefore stands best, and does not swell and crush the timbers. In some drifts the rock stands without being timbered. The main north and south drift, generally the first reached after leaving a station in a mine, is the highway of the level in which it is opened. It has a car-track running through its whole length, and, in some cases, as in the main drift on the 1500-foot level of the consolidated Virginia and California mines, contains a double car-track.

The cross-cuts are the same kind of openings as the drifts, but they are smaller and run across the course of the vein—run east and west. They start from the main drift, and are pushed out into the vein and ore-body, if ore-body there be. Pushed out in this way from the main drift at intervals of about 100 feet, they cut through and “prospect” the vein. The progress of the cross-cuts on a new level in a leading mine on the Comstock is always watched with great interest by all the “mining experts,” “stock sharps,” and mining men generally.

Car-tracks are laid in all of the cross-cuts, and connect with the track of the main drift by means of turn-tables. The cross-cuts are pushed through the vein to its opposite wall, in order that the whole of the ground may be thoroughly explored and its boundaries defined. In order to secure a free circulation of air on the level, they are frequently connected at various points by cross-drifts.

Winzes are small shafts sunk from one level to another in the mine. They are sunk in any place where they may happen to be required. Some are sunk vertically, but many follow the foot-wall of the vein, and thus go down at an angle of from thirty-five to forty-five degrees. All are of great use for the purpose of ventilation, and those that are sunk at an angle are very frequently properly planked up, and used as chutes through which to send ore or timbers to a lower level. In all mines will be found a great number of these chutes. Sometimes the men fall into them. When this happens they are always to be found at the bottom, on the level below, immediately after. Generally, men are not very badly hurt by sliding through an ordinary chute, yet not a few have been killed by such a fall, and many have had bones broken.

In going down a chute much depends upon the angle of the opening—the steeper, the more danger there is in making the trip. On the surface of the earth all the vertical winzes would be called shafts, and what are called drifts and cross-cuts below would be called tunnels, were they where their mouths came out on the surface. An “upraise” is where the miners begin on a lower level and dig upward toward a higher. While it is going up, it is an upraise, but when it is connected with the level above it is a winze. Should it never reach the level for which it was started it remains an upraise for all time.

Winzes are very often thus made—one set of miners being engaged below at digging up, while above another set are digging down. The progress made by the men below is always much more rapid than that of the men above, as every ounce of dirt loosened at once falls down out of the way.

When the ore-body has been properly opened, explored, and ventilated by means of drifts, cross-cuts, and winzes, the work of extraction is commenced.

The first opening is made on the “track-floor” of the level—the floor on which are run the drifts and cross-cuts wherein are laid the car-tracks—and in the bottom of this opening or chamber are put down the sills for the first “square-set” of timbers.

The timbers used as supports in a mine are from twelve to fourteen inches square. The posts are six feet, and the caps five feet, in length. The upper ends of the posts are framed in such a manner that the ends of four caps may rest upon each, and leave a mortise in the centre, in which to insert the tenon of the post of the next “set”; on the top of this is a place for another post, and so the work of building up sets goes on to any height that may be required.

As the ore is extracted at the sides of the first set, the same squares of timbers are built up in those places, and there is formed a sort of pyramid of cribs, rising constantly as the work of extracting the ore proceeds. The top sets of this pyramid are secured closely against the ore, by means of large wooden wedges, and the side sets are also wedged up against the ore in the same way, as they are carried up. In this way the mass of ore overhead is supported at all points by the cribs of timbers, except here and there where chambers are being excavated in the ore-body for new sets.

Thus are squares of timbers constantly added, and the pyramid carried up till the ore has been worked out to the level above. If the level above has been worked out, it is already filled with the same square sets as are being built up from below, and the latter rise into their proper places and fit as neatly as the squares on a checker or chess-board.

The sets are six feet in height by five feet in width, and as they rise, floors of strong plank are laid upon each set. Thus there are seen floors some six feet apart from the bottom to the top of the level.

In these floors are square openings as for trap-doors, with short flights of steps leading from floor to floor. The floors are pushed out against the breasts of ore on all sides as the stope is extended. A light blast of giant-powder being exploded in the face of the ore-breast, the mass is shattered, and is then easily pulled down by the picks of the miners.

As the ore is dug down it falls upon the floors, from which it is easily shovelled into the wheelbarrows, by means of which it is carried to the chutes. These chutes lead down to ore-bins on the track-floor, where the cars are loaded which carry the ore to the main shaft and finally up to the surface, and out along a track which leads to the ore-house, from which it is sent to the mills. This is the method of timbering mines that was invented by Mr. Philip Deidesheimer, in the early days of Washoe, when he was superintendent of the old Ophir mine. The building up of timbers in square sets or cribs is found to be exactly what is required, as a cavity of any size, however great, can by this plan be filled up and its roof supported.

In order to still further secure the mine, it is usual to plank or timber up a section of four of these square sets, and fill them in from bottom to top with waste rock. Thus is provided a large column of stone reaching up to and supporting the roof of the mine. Such columns are constructed in a number of places, at suitable intervals throughout each level of the mine, and they are found to stand more strain than would all of the timber that could be piled into a level. Being built up of loose rocks they gradually yield for a time, but still stand as firmly in their places as before, whereas a solid column of stone would be crushed into a thousand fragments, and would let down the whole upper part of the mine.

In some mines many blocks of porphyry and other barren rock are found with the ore, making it necessary to do a great deal of assorting, but in the Consolidated Virginia mine there is no work of this kind to be done, at least not on the 1500-foot level, where they are sloping out in the bonanza. There is nothing to do but dig down the rich masses of black sulphuret and chloride ores, shovel them into the cars, and send them to the surface to be taken to the mills, and the same is the case in the California mine.

Samples are taken from each car-load of ore down in the mine, when it reaches the main shaft; at the surface other samples are taken, and at the mills samples are taken of the pulp, every hour, as it runs from the batteries—in short, the ore is sampled everywhere, and at all stages in the handling, from the ore-breasts till it has passed through the mills, and finally appears in the shape of large, shining silver bricks, each weighing a hundred pounds or more. All the samples thus taken are carefully assayed, and the results compared and noted.

An incline is simply an inclined extension of the main shaft, from some convenient point below, or rather at or near the point where the shaft strikes the west wall of the vein. The Comstock lode dips to the eastward at an angle of from thirty-five to forty-five degrees, and as the main working shaft of a mine is always sunk to a considerable distance—a thousand feet or more—to the eastward of the croppings [_i. e._ that part of the lode which comes to the surface of the earth], the west wall is not reached until the shaft has attained a depth of from 1000 to 1500 feet, depending upon how far east of the croppings it was sunk.

The main incline of a mine is of about the same dimensions as the main shaft, and is timbered in much the same way. In the Consolidated Virginia mine there is as yet no incline, but at the Crown Point mine is to be seen one that is a model in every respect. This incline starts at the 1100-foot level, from the bottom of the vertical shaft, and goes down with the dip of the vein (at an angle of about thirty-five degrees), to the 1700-foot level, its present terminus. A track is laid on its bottom, of ordinary railroad iron, and as neither cages nor a car of the usual pattern can be used in an incline, recourse is had to another device. A kind of car called a “giraffe” is used for hoisting through an incline. It has low wheels in front and high ones behind; thus the body of the giraffe stands level, the same as a common ore-car on an ordinary track.

The giraffe is capable of carrying eight tons of ore—more than eight ordinary car-loads. It is lowered down the track to the bottom of the incline, and hauled up to the foot of the shaft by means of a round steel-wire cable which runs upon a reel at the surface.

The cable passes over a large iron pulley at the top of the vertical shaft, and _under_ a second pulley of the same kind at its bottom. The cable is also supported by rollers, placed in the centre of the track, as it travels up and down the incline, otherwise its great weight would cause it to drag upon the ground. From the upper side of an incline, stations are made, the same as they are made at intervals along a vertical shaft; drifts are then run, and the work of cross-cutting and prospecting the vein goes on in the same way as when the ore-body is approached by means of a shaft. The giraffe has in front and on the “outside” two seats, facing each other, on which six passengers can ride very comfortably. Sometimes there is hitched behind the giraffe a second car of the same pattern, called the “back-action.”

There is not a little of novelty in a ride up an incline on a “giraffe.” The conductor of the “train,” who is seated by our side, gives the signal for starting by pulling a wire and striking upon the engineer’s bell—far away up the incline and up the vertical shaft, and some distance beyond that again in the engine-house—a certain number of strokes. Instantly we start, and soon are darting up the steep iron way at a terrific rate of speed. Lamps are placed at intervals on the sides of the incline; besides, we carry lanterns, and there are lights burning at all the stations. Thus our underground railroad is well lighted up. We have a good view of the track, and can see the rails glistening far ahead of and above us.

We rush up this steep road so rapidly that the posts along the sides of the incline resemble a fine-toothed comb. To look ahead and see before you, and high above you, a hundred yards or more of semi-vertical railroad, up which you are thundering at whirlwind speed, is strikingly the reverse of natural. Going down does not in any way interfere with your notions of the “eternal fitness of things,” for it is quite natural for anything that is loose to run down hill, but this fierce darting up the steep iron rails somewhat unsettles you.

Up this queer railroad you are hurled through the caverns of the gazing Troglodytes, till you reach the foot of the vertical shaft, when they transfer you to a cage, and you are shot out at the top, much as the “Red Gnome,” in the play, is shot up through the trap in the stage-floor of a theatre.

A giraffe is provided with a safety-apparatus somewhat similar to that on a cage. A large wooden rail runs the whole length of the track. Extending from the side of the giraffe, and almost clasping this rail, are two toothed, eccentric wheels. Should the cable break, these wheels would instantly grasp and clasp the rail, and the greater the weight upon the car the more fiercely they would bite into the wood, and retain their hold upon it. This invention has been the means of saving scores of lives.

The “sump” is the well or hole sunk below the bottom of a shaft, for the purpose of holding the water flowing in from above. In this is placed the “suction” of the pump, and into it is collected the water from all parts of the mine. Although “sump” is now considered an English word, it was doubtless derived from the German word, “sumpf,” which means a marsh, pool, bog, or fen. When miners fall down a shaft it is frequently necessary to fish their mangled remains out of the sump with grappling irons.

As some persons may desire to know how sinking can be carried on in the bottom of a shaft where there is a strong influx of water, it may be well to explain the matter. On the end of the pump-column or tube which comes down near to the bottom of the shaft, is a piece of flexible hose, the same as the “suction” of a fire-engine, and this is moved about from side to side in the shaft, always keeping the end of it in the low places where the water collects.

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