Chapter 2

The Sutro drain tunnel (nearly four miles in length) connects with the shaft at a depth of 1,600 ft., up to which point all the water encountered below is pumped. The shaft was sunk to the depth of 2,200 ft. before more water was encountered than could be hoisted out in the "skips" with the dirt. At the 2,200 level two Cornish pumps, each with columns fifteen inches in diameter, were put in. At the 2,400 level the same pumps were used. On this level a drift was run that connected with the old Hale & Norcross and Savage shafts, producing a good circulation of air both in the shaft and in the mines mentioned. At this point, on account of the inflow from the mines consequent upon connecting with them by means of the drift, they had more water than the Cornish pumps could handle, and introduced the hydraulic pumps, which pumps are run by the pressure of water from the surface through a pipe running down from the top of the shaft, whereas the Cornish pumps are run by huge steam engines.

By means of the hydraulic pumps they were enabled to sink the shaft to the 2,600 level, and extended the Cornish pumps to that point, where another set of hydraulic pumps was put in. They then sunk the shaft to the 2,800 level, when they ran another drift westward, and tapped the vein. The prospects at this depth in the Hale & Norcross and Chollar mines were so encouraging that the management decided to sink the shaft to the depth of 3,000 ft. On reaching the 3,000 level, they ran a third drift through to the vein. The distance from the shaft to the east wall of the vein was found to be only 250 ft. At the depth of 3,000 ft. they put in one of the pair of hydraulic pumps that is to be set up there. The second pump is now arriving from San Francisco, and as soon as the several parts are on the ground, it will be at once put in place alongside its fellow on the 3,000 level. This additional pump will increase the capacity from 600,000 to 700,000 gallons in twenty-four hours, or about forty-five miners' inches.

Owing to the excellent showing of ore obtained on the 3,000 level by the Hale & Norcross Company, and to the continuation of the ore below that level (as shown by a winze sunk in the vein), the management determined to sink the shaft to the vertical depth of 3,200 ft. It is now 3,120 ft. deep, and it is safe to say that it will reach the depth of 3,200 ft. early in September, when it will lack but eighty feet of being as deep as the shaft at Przibram was at the time of the great festival. Although the shaft is of great size--about thirty feet by ten feet before the timbers are put in--the workmen lower it at the rate of about three feet a day, in rock as hard as flint.

The hydraulic pump now working at the 3,000 foot level of the shaft is the deepest in the world. In Europe the deepest is in a mine in the Hartz Mountains, Germany, which is working at the depth of 2,700 feet. It is, however, a small pump not half the size of the one in the Combination shaft. Although these pumps were first used in Europe, those in operation here are far superior in size, and in every other respect, to those of the Old World, several valuable improvements having been made in them by the machinists of the Pacific coast.

The capacity of the two Cornish pumps, which lift the water from the 2,900 foot level to the Sutro drain tunnel (at the 1,600 level), is about 1,000,000 gallons in twenty-four hours, and the capacity of the present hydraulic pumps is 3,500,000 gallons in the same time. They are now daily pumping, with both hydraulic and Cornish pumps, about 4,000,000 gallons, but could pump at least 500,000 gallons more in twenty-four hours than they are now doing. The daily capacity with the hydraulic pump now coming, and which will be set up as mate to that now in operation at the 3,000 foot level, will be 5,200,000 gallons.

The water which feeds the pressure pipe of the three sets of hydraulic pumps is brought from near Lake Tahoe, in the Sierra Nevada Mountains. The distance is about thirty miles, and the greater part of the way the water flows through iron pipes, which at one point cross a depression 1,720 feet in depth. The pressure pipe takes this water from a tank situated on the eastern slope of Mount Davidson, 3,500 feet west of the shaft. At the tank this pipe is twelve inches in diameter, but is only eight inches where it enters the top of the shaft. The tank whence the water is taken is 426 feet higher than the top of the shaft, therefore the vertical pressure upon the hydraulic pump at the 3,000 foot level is 3,426 feet. The pressure pipe is of ordinary galvanized iron where it receives the water at the tank, but gradually grows thicker and stronger, and at the 3,000 level it is constructed of cast iron, and is 2½ inches in thickness. The pressure at this point is 1,500 pounds to the square inch.

In the early days of hydraulic mining in California the miners thought that with a vertical pressure of 300 feet they could almost tear the world to pieces, and not a man among them could have been made to believe that any pipe could be constructed that would withstand a vertical pressure of 1,000 feet; but we now see that a thickness of two and a half inches of cast iron will sustain a vertical pressure of over 3,400 feet.

There is only one pressure pipe for all the hydraulic pumps. This extends from the tank on the side of the mountain to the 3,000 foot level. It is tapped at the points where are situated the several sets of hydraulic pumps. The water from the pressure pipe enters one part of the pump, where it moves a piston-back and forth, just as the piston of a steam engine is moved by steam. This water engine moves a pump which not only raises to the surface the water which has been used as driving power, but also a vast quantity of water from the shaft, all of which is forced up to the Sutro drain tunnel through what is called a return pipe. Each set of hydraulic pumps has its return pipe; therefore there are three return pipes--one from the 2,400, one from the 2,600, and another from the 3,000 level.

Some idea may be formed of the great size of these hydraulic engines when it is known that the stations excavated for them at the several levels where they are placed are 85 feet long, 28 feet wide, and 12 feet high. All this space is so filled with machinery that only sufficient room is left to allow of the workmen moving about it. One of these stations would, on the surface, form a hall large enough for a ball room, and to those who are unacquainted with the skill of our miners it must seem wonderful that such great openings can be made and securely supported far down in the bowels of the earth; yet it is very effectually done. These great subterranean halls are supported by timbers 14×16 inches square set along the walls three feet apart, from center to center, and the caps or joists passing overhead are timbers of the same size. The timber used is mountain spruce. Not one of these huge stations has thus far cost one dollar for repairs. The station at the 2,400 level has been in use five years, that at the 2,600 three years, and the one at the 3,000 level eight months. Room for ventilation is left behind the timbers, and all are still sound. Timbers of the same kind are used in the shaft, and all are sound. The shaft has cost nothing for repairs. Being in hard andesite rock from top to bottom, the ground does not swell and crowd upon the timbers.

If it shall be thought advisable to go to a greater depth than 3,200 feet, a station of large size will be made on the east side of the present shaft, and in this station will be sunk a shaft of smaller size. The reason why the work will be continued in this way is that in a single hoist of 3,200 feet the weight of a steel wire cable of that length is very great--so great that the loaded cage it brings up is a mere trifle in comparison. In this secondary shaft the hoisting apparatus and pumps will be run by means of compressed air. As it is very expensive to make compressed air by steam power, the pressure pipe will be tapped at the level of the Sutro tunnel, and a stream of water taken out that will be used in running a turbine wheel of sufficient capacity to drive three air compressors. As there will be a vertical pressure upon the turbine at this depth of over 2,000 feet, a large stream of water will not be required. The water used in driving the wheel will flow out through the Sutro tunnel, and give no trouble in the shaft.

By means of this great shaft and its powerful hydraulic and Cornish pumps the crust of the earth will probably yet be penetrated to far greater depth than in any other place in the world. It has been only a little over ten years since the work of sinking it was begun, whereas in the mines of the Old World they have been delving since "time whereof the memory of man runneth not to the contrary." The work on the Combination shaft has been by no means continuous. There have been long stoppages aside from those required at such times as they were engaged in running long drifts to the westward to tap the vein, and at times for many months, when the several companies interested in the shaft were engaged in prospecting the various levels it had opened up.

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REMARKABLE WELLS AND CAVERNS.

Yucatan is one of the most interesting States of Mexico, owing to the splendid ancient palaces and temples of once grand cities, now hidden in the forests. That country also presents great attractions for geologists and botanists, as well as naturalists, who there find rare and beautiful birds, insects, and reptiles.

There are no rivers on the surface of the land, but in many parts it is entirely undermined by extensive caverns, in which are basins of water fed by subterranean currents. The caverns are delightfully cool even at midday, and the fantastic forms of some of the stalactites and stalagmites are a never-ending source of interest. There are long winding passages and roomy chambers following one after another for great distances, with here and there some chink in the stony vault above, through which a sunbeam penetrates, enabling us to see to the right and left openings leading to untrodden places in the bowels of the earth. As few of these caves have been explored, the wildest accounts are given by the natives concerning the dark recesses where only wild beasts seek shelter. Before venturing far in, it is advisable to secure one end of a ball of twine at the entrance, and keep the ball in hand; nor is it safe to go without lanterns or torches, lest we step into some yawning chasm or deep water. The leader of one party suddenly saw a very dark spot just before him; he jumped over, instead of stepping on it, and told the others to halt. Examination proved the dark patch to be a pit that seemed bottomless.

Awe-inspiring as are the interiors of some of these caves, they are frequently most beautiful. The natural pillars are often grand in dimensions and sparkling with various hues, while stalactites and stalagmites sometimes resemble familiar objects with astonishing perfection. It is, however, not advisable to place implicit confidence in accounts of the natives, for the reality, no matter how beautiful, can hardly be equal to what the vivid imagination of the Indian has pictured. Anything bearing the least resemblance to a woman is called "a most beautiful Virgin Mary." Fantastic flutings become "an organ," and a level rock "an altar." Only once we were not disappointed, when, having been told to look for a pulpit, we found one that appeared as if man must have fashioned it, supported on a slender pyramidal base, the upper part very symmetrical, and ornamented with a perfect imitation of bunches of grapes and other fruit.

As I have already said, in these caves are sheets of water, some very large, others only a few feet in circumference, fed by subterranean currents. When the water is clear and sweet, it is peopled by a kind of bagre, a blind fish called by the natives _tzau_, also a species of _Silurus_. But there are likewise medicinal and thermal waters, by bathing in which many people claim to have been cured of most painful and obstinate diseases.

Strange stories are told of some of these waters. Of one it is said that those who approach it without holding their breath fall dead. People who live near the place swear it is so, and say the water appears to boil on such occasions. From the thermal waters, in some cases 100 feet below the soil, and without means of access except by buckets let down through an opening in the rock, warm vapors issue at early morn, but when the sun is high the water is cool and pleasant to drink.

The name _senote_ is given to all these deposits of water, also to some immense natural circular wells from 50 to 300 feet in diameter. The walls are more or less perpendicular, generally covered with tropical vegetation. The current in some is swift, but no inlets or outlets are visible. The water is deliciously pure and sweet, much better than that of wells opened by man in the same country. These enormous deposits generally have a rugged path, sometimes very steep, leading to the water's edge, but daring natives throw themselves from the brink, afterward ascending by stout roots that hang like ropes down the walls, the trees above sucking through these roots the life-sustaining fluid more than a hundred feet below.

In the west part of Yucatan is a village called _Bolonchen_ (nine wells), because in the public square there are nine circular openings cut through a stratum of rock. They are mouths of one immense cistern, if natural or made by hand the natives do not know, but in times of drought it is empty, which shows that it is not supplied by any subterranean spring. Then the people depend entirely on water found in a cave a mile and a half from the village; it is perhaps the most remarkable cavern in the whole country. The entrance is magnificently wild and picturesque. It is necessary to carry torches, for the way is dark and dangerous. After advancing sixty or seventy feet we descend a strong but rough ladder twenty feet long, placed against a very precipitous rock. Not the faintest glimmer of daylight reaches that spot; but after a while we stand on the brink of a perpendicular precipice, the bottom of which is strongly illuminated through a hole in the surface rock more than 200 feet above. Standing on the verge of this awful pit in the dim light, the rocks and crags seem to take on most weird shapes. We go down into the great hole by a ladder eighty feet high and twelve wide, and, reaching the bottom, are as yet but at the mouth of the cave, which, by the bye, is called _Xtacunbi Xunan_ (the hidden lady), because, say the Indians, a lady was stolen from her mother and hidden there by her lover. Now, to our right, we find a narrow passage, and soon another ladder; the darkness is intense and the descent continuous, though irregular, like a series of hills and dales, ladders being placed against the steepest places.

After an exhausting journey we reach a vast chamber, from which crooked passages lead in various directions to wells, seven in all, each named according to the peculiar kind of water. One, always warm, is called _Chocohá_ (hot water); another, _O[c]ihá_* (milky water), and _Akabhá_ (dark water). About 400 paces away from the chamber, passing through a very narrow, close passage, there is a basin of red water that ebbs and flows like the sea, receding with the south wind, increasing with the northwest.

*Transcriber's note: [c] denotes upside-down 'c' in original.

To reach the most distant well, we go down yet one more ladder, the seventh. On one side of it there is a perpendicular wall, on the other a yawning gulf, so when one of the steps, merely round sticks tied with withes, gave way beneath our feet, we tightly grasped the stick above. Having reached the bottom of the ladder, we crawl on our hands and feet through a broken, winding passage about 800 feet long, then see before us a basin of crystalline water, and how thirsty we are! This basin is 1,400 feet from the mouth of the cave, and about 450 feet below the earth's surface. Several hundred people during five months in every year depend entirely on that source for all the water they use. With their frail pitchers and flaring torches they wend their way, gasping for breath, through the intricate passages, and reaching the water, are so profusely perspiring that they must wait before quenching their thirst. The way back is even harder, and they are tired and loaded; yet these people are such lovers of cleanliness that on their arrival at their poor huts, before tasting food, they will use some of the water that has cost them so much, to bathe their smoke-begrimed skin. As several women once fainted in the cave, men generally fetch the water now.

Yucatan is, and has been for ages past, quite free from earthquakes, while all surrounding countries are from time to time convulsed. This immunity may be due to the vast caverns and numerous great wells existing throughout the land. Pliny the Elder was of opinion that if numerous deep wells were made in the earth to serve as outlets for the gases that disturb its upper strata, the strength of the earthquakes would be diminished, and if we may judge by Yucatan, Pliny was right in his conjectures. After him, other scientists who have carefully studied the subject have expressed the same opinion with regard to the efficacy of large wells.

ALICE D. LE PLONGEON.

Brooklyn, July 15, 1885.

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Cholera failed to strike a single one of the 4,000 women employed in the national tobacco factory at Valencia, Spain, though the disease raged violently in that city, and the _Medical World_ recalls that tobacco workers were also noticed to enjoy exemption from attack during an epidemic at Amsterdam.

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THE CABBAGE BUTTERFLY.

A patch of eggs and the minute caterpillars or larvæ nearly emerged from them are seen on the leaf. These tiny eggs are at first quite white or pale yellow, and form an object for the microscope of remarkable beauty, which is worthy of the examination of all who take an interest in the garden and its insect life. An egg magnified is drawn at the bottom left-hand corner of the woodcut. When the eggs are near the hatching point they darken in color, and a magnifying glass reveals through the delicate transparent shell a sight which fills the observer with amazement; the embryo caterpillar is seen in gradual course of formation, and if patience and warmth have permitted it, the observer will witness slight movements within the life-case, and presently the shell will break and a black head with moving jaws will be thrust out; the little caterpillar unfolds and slowly crawls away from the egg-shell, and inserts its jaws into the green leaf. It is curious to witness how judiciously the little creatures avoid crowding together, but strike out in different directions, and thus they make sure of a plentiful supply of food, and distribute the effects of their depredations. These caterpillars eat continually, and hence rapidly increase in size, until they present the appearance shown in our drawing at the bottom of the illustration, which is a full grown caterpillar.

It will be observed that this insect is composed of thirteen segments from head to tail, which is a distinctive characteristic of all insects both in the larval and perfect states; but in the case of this and most other caterpillars these segments are sharply defined and readily recognized. It will also be noticed that the three segments or "joints" nearest the head bear a pair of legs each; these are the real feet, or claspers, as they are sometimes termed, which develop into the feet of the future butterfly. There are four pairs of false feet or suckers, which adhere to the ground by suction, and which disappear in the butterfly. On the last or tail end is a fifth pair of suckers also, which can attach themselves to a surface with considerable force, as any one can attest who has noticed the wrigglings of one of these caterpillars when feeling for new feeding ground.

The caterpillar now ceases to eat, and quietly betakes itself to a secluded corner, where in peace it spins a web around its body, and wrapt therein remains quiescent, awaiting its change into the butterfly. Although so dormant outwardly, activity reigns inside; processes are going on within that chrysalis-case which are the amazement and the puzzle of all naturalists. In course of time the worm is changed into the beautiful winged butterfly, which breaks its case and emerges soft and wet; but it quickly dries and spreads its wings to commence its life in the air and sunshine. The chrysalis is represented in the figure on the left. The butterfly, it will be recognized, is one of the common insects so familiar to all, with strongly veined white wings, bearing three black spots, two on the upper and one on the lower wing, and dark coloring on the corner of the upper wings. The antennæ, as with all butterflies, are clubbed at the extremity--unlike moths', which are tapering--and the large black staring eyes are the optical apparatus, containing, we are told, thousands of lenses, each a perfect, simple eye.

The wings derive their chief coloring from the covering of scales, which lie on like slates on a roof, and are attached in a similar manner. A small portion of the wing magnified is represented at the bottom right hand corner, and detached scales more highly magnified next to it, exhibiting somewhat the form of battledoors.

THE PEACOCK BUTTERFLY.

Another well known insect is illustrated in the figure in the upper portion--the peacock butterfly (Vanessa Io). The curious spiked and spotted caterpillar feeds upon the common nettle. This beautiful butterfly--common in most districts--is brilliantly colored and figured on the upper side of the wings, but only of a mottled brown on the under surface, somewhat resembling a dried and brown leaf, so that it is no easy matter to detect the conspicuous, brightly-decked insect when it alights from flight upon foliage, and brings its wings together over its back after the manner of butterflies. At the left-hand corner is seen the head of the insect, magnified, showing the long spiral tongue.

This is a curious structure, and one that will repay the trouble of microscopic examination. In the figure the profile is seen, the large compound eye at the side and the long curved tongue, so elephantine-looking in form, though of minute size, is seen unrolled as it is when about to be inserted into flowers to pump up the honey-juice. This little piece of insect apparatus is a mass of muscles and sensitive nerves comprising a machine of greater complexity and of no less precision in its action than the modern printing machine. When not in use, the tongue rolls into a spiral and disappears under the head. A butterfly's tongue may readily be unrolled by carefully inserting a pin within the first spiral and gently drawing it out.--_The Gardeners' Chronicle._

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THE BHOTAN CYPRESS.

(CUPRESSUS TORULOSA.)