CHAPTER XXIII.
HOW THE MINES ARE WORKED.
When the upper line of bonanzas had been worked out, and the shafts were sunk to greater depths in search of new bodies of ore, they eventually attained such a depth as brought them down upon the barren syenite forming the west wall. The shafts were then deflected from the vertical and passed down along the syenitic foot-wall to the eastward, in the shape of an incline. At length it was seen that these inclines were becoming too long to permit of their being worked through to advantage with the machinery then in use, and company after company moved to the eastward, a distance of a thousand feet or more, and then established a new line of shafts, over which they set up new and more powerful machinery than had yet been seen on the lead. These shafts did not strike the lead until they had been sunk to the depth of one thousand or one thousand two hundred feet, whereas the first line of shafts were either sunk on the lead, or at such a distance in front of the croppings as to tap it at the depth of from two to five hundred feet.
A third line of shafts had been commenced in 1875, and one of these, which is now being sunk by the Savage, Hale, & Norcross, and the Challar-Potosi Companies combined, is nearly a mile east of the croppings. This is intended to be a shaft for all time. It will be of vast size, containing several spacious compartments for hoisting and pumping purposes, and will be supplied with the most powerful machinery that can be manufactured. It will require some years to sink this shaft to a point where it will intersect the vein; meantime the several companies will continue to work through their present shafts and inclines.
[Illustration:
WASTE ROCK DUMPS. (_Challar, Potosi, Savage, Hale & Norcross Mines._) ]
The Savage Company are prepared to sink the incline of their present shaft to the great depth of four thousand feet. For this purpose they have set up new hoisting machinery of novel construction and of the most powerful description. The reel on which the hoisting-cable winds is a novelty for the first time introduced on the Comstock lode, and a brief description of it and the cable used upon it may not be without interest for the general reader.
The reel is fifteen feet in length, and at the larger end is twenty-two feet in diameter, while at the smaller end the diameter is but thirteen feet. It is suspended upon a wrought iron shaft about sixteen inches in diameter, the ends of which revolve in ponderous bearings supported by foundations of cut stone reaching into the earth to solid rock. The shell of the reel is covered with thick wooden staves, and the whole somewhat resembles a great tapering cask. Over the staves are securely bolted heavy iron plates forming a strong armor outside of the wooden structure. In this iron armor is a deep groove which, starting at the smaller end of the great conical drum, runs in a spiral manner to the larger end; just as the groove between the threads of a screw is seen to run. In this groove winds the cable as the incline-car (“giraffe”) is let down into or drawn up out of the mine.
When the car is at the bottom of the incline, the greater part of the cable is off the reel, and when the hoisting begins it is wound up on the smaller end of the drum, where the engines have greater purchase on the load. As the hoisting proceeds, and the weight to be raised becomes momentarily lighter, on account of the heavy steel cable being wound up, the lifting force is steadily moved toward the larger end of the drum, and each revolution adds to the swiftness of the ascent of the car that is being raised. The cable is round, and is made of the best steel wire. It is 4,000 feet in length, and weighs 25,190 pounds. The upper part, for a distance of 1,500 feet down, is two inches in diameter; for the remainder of its length, 2,000 feet, it gradually tapers till at the lower end its diameter is one and three-quarter inches. The taper is not made by dropping wires in the several strands of the rope, but by drawing each wire (as it is manufactured) slightly tapering for the last 2,500 feet of its length.
The incline hoisting-works stand a short distance from the building in which is contained the hoisting machinery of the vertical shaft, and the cable, after entering the latter building, is carried over a large iron pulley or sheave that is placed over the main shaft. Thence it passes down a compartment of the main shaft a vertical distance of 1,300 feet, when it passes _under_ a second sheave and continues down the incline to its bottom.
The car used in the incline runs on an iron track, holds about five tons of rock, and is capable of hoisting (easily) from 480 to 500 tons per 24 hours. The car is made wholly of iron and steel.
When this incline car has been hauled up as far as the bottom of the vertical shaft, that is, to within 1,300 feet of the surface, it there dumps its load by means of a self-acting gate in its bottom. The rock thus dumped from the incline-car is then taken in smaller cars and sent to the surface on cages that ply up and down the hoisting-compartments of the main vertical shaft.
The engines for driving the huge reel, and thus hoisting this iron car or “giraffe,” with its load of ore and the 25,000 pounds of cable, are two in number and of 200-horse power each. A precisely similar hoisting apparatus has since been set up at the Ophir mine; indeed, the drawings for this powerful machinery were first made for the Ophir Company. The length and weight of cable at the Ophir is the same as that in use at the Savage mines.
Some of the old shafts opened on and about the first or upper line of bonanzas have quite gone to decay. They still stand, but the timbers in many places, far down in the bowels of the earth, are racked and rotten; while the timbers built up in the mine to support the chambers from which ore was extracted, and set up in the galleries, drifts, cross-cuts, and chutes, millions on millions of feet in all, have quite gone to decay. It is perilous to undertake the exploration of these old worked-out levels. In many places they are caved in every direction, the old floors are rotten, water drips from above, a hot musty atmosphere and almost stifles the explorer, and in places, the air is so foul that his candle is almost extinguished.
Down in these deserted and dreary old levels, hundreds of feet beneath the surface, are encountered fungi of monstrous growth and most uncouth and uncanny form. They cover the old posts in great moist, dew-distilling masses, and depend from the timbers overhead in broad slimy curtains, or hang down like long squirming serpents or the twisted horns of the ram. Some of these take most fantastic shapes, almost exactly counterfeiting things seen on the surface. Specimens of these are to be seen in most of the cabinets of curiosities in Virginia City. Some of the fungi that grow up from the bottoms of old disused drifts are wholly mineral and are composed of minute crystals of such salts as are contained in the earth from which they spring.
These old, decaying places breed all manner of gases, some of them, as the firedamp (carburetted hydrogen gas), dangerous to human life.
One winter night, in 1874, some of the residents of the western part of Virginia City were startled by seeing what seemed a column of flame fifty or sixty feet in height, shooting up from the mouth of an old shaft near the old upper works of the Ophir Company. It was at first thought that the timbers in the old mine were on fire, and three or four men ran to the spot to see what could be done toward smothering the flames.
On reaching the shaft, however, they found that there was no smell of smoke, and also that the supposed fire was a light unlike anything they had ever before seen, in its weird whiteness and the strange coruscations of its component particles, the light shed about by the flame, the faces of the men were of a corpse-like pallor. Their clothing and hair also partook in some degree of the same ghastly and unnatural hue. The light came up the full size of the large square shaft, and seen at a distance, as it rose through the falling snow, closely resembled one of the shooting spires of the aurora borealis, and it exhibited something of the same waving and inconstant motion.
Although the men felt creeping over them a sort of superstitious awe, they still had sufficient courage to approach the shaft and gaze into it. A strange sight was there seen. The whole interior of the shaft seemed to be at a white heat, and glowed like a furnace. The timbers on the sides were particularly brilliant. Each splinter, excrescence, or bit of fungus seemed darting dazzling rays that streamed steadily out in all directions. A warm, strange current of air ascended from the sweltering regions below, and there was observed a musty, sickening smell. All of those who looked into the shaft afterwards felt a severe pain in the temples, and two or three were made sick at the stomach.
This strange appearance lasted over half an hour, and before it ended a crowd of a dozen or more miners returning from their work had collected about the shaft. The light died out from the top downwards, and protuberances from the sides of the shaft continued to glow for some minutes after the light was no longer visible at its top. This remarkable phenomenon was undoubtedly caused by the belching forth of a highly phosphurated gas of some kind from the deep, underground chambers of the old abandoned works. The rush of this gas was probably caused by an extensive cave in a place where the timbers had rotted away. One of the men who witnessed the spectacle was of the opinion that the mingling of the gas from the mine with the atmospheric air had something to do with intensifying the light. He observed in the ascending current of pseudo-flame myriads of small particles of some substance of a floss-like texture, which appeared to flash and glow as they darted upward, and which presented in the general column of light much the same appearance as motes moving about in a sunbeam.
In February, 1874, some miners at work in the Utah mine, just north of Virginia City, were all made temporarily blind by certain water or gases which they encountered. They were running a drift at the depth of 400 feet to connect with some old, flooded works. When the end of the drift neared the old works, the water they contained began to be drained off. The water had attained a great height, and the pressure was so strong that it sent streams darting and hissing from every hole and crevice in the rock in which the drift was being run. In places, these streams of water spurted out with as much force as though they had been thrown by a hydraulic pipe.
The water, or the steam and gases from it, poisoned all who worked in the drift. Their heads and faces were so swollen that their eyes were closed, and all were thus rendered blind for some days. A few years before, the same thing occurred in the Savage and the Yellow-Jacket mines, when drifts were run to tap old flooded works in which rotten timbers were soaking. Quite recently, all the miners at work in the Sutro Tunnel were poisoned, and had their eyes closed for some days by the tapping of a shaft which had been filled with water for two or three years. All who are thus poisoned speedily recover by remaining above ground for three or four days.
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