Ar-tesian well.
Artesian wells are so called because it was generally supposed that they were first used in the province of
Artois, France.
They appear, however, to have existed in
Egypt at a very remote date, and are said to be found in the province of On-
Tong-Kiao, in
China, of the depth of from 1,500 to 1,800 feet. The principle of their action is this: water percolating through pervious strata, such as sand, gravel, or chalk, is finally arrested in its downward course by an impervious stratum of rock or clay, causing it to accumulate in the pervious stratum above as in a reservoir, and when the source of supply is higher than the level of the ground at the place where the well is bored, the water will rise to the surface, or even considerably above it; in many cases issuing from the mouth of the well with sufficient force to throw a jet of the water to a great hight, or admit of its being carried high enough for distribution to the upper stories of buildings.
The term “artesian” is only properly applied to wells in which the water rises to or above the surface, so that in case a large number are collected in a single neighborhood, some or all of them, particularly those toward the higher part of the basin, may become converted from artesian into ordinary wells.
In the
London basin, where a great number of artesian wells have been bored, the general level of the water has been very much diminished.
It generally happens that more than one, frequently many, water-bearing strata are penetrated before one is reached which has a sufficient head to cause an overflow at the surface; in such cases others besides the lower one may be made available, if thought advisable.
The wells of the
London basin will perhaps afford as good an illustration of the theory and action of artesian wells as any other example; the character and succession of the beds having been more carefully studied and worked out than almost any others where such wells are located.
These wells derive their supply from the pervious strata of the plastic clay and chalk.
These strata are covered in part by the formation called the
London clay, which is, in most of its beds, tough and impermeable to water, so that the rain falling on those parts of the porous chalk and other pervious strata below it, which are not covered by the superjacent impervious clay, percolates through them till its farther progress downward is stopped by the “gault,” another stratum of impervious clay, and accumulates tween it and the overlying clay, which acts as a cover to this vast subterraneous reservoir to the level of the line
B A. The water, reaching points, as C, at the lower levels of the junction of the chalk and clay, the pervious and the impervious strata, comes to the surface in the form of springs which act as dischargeoutlets.
In this case a horizontal line, as
A B, drawn through
C, indicates the general level of the water in the basin, unless disturbed by faults or shifts in the strata permitting a part to be carried off at a lower level.
In the latter case, if the outlet had an area of capacity for carrying off an amount in excess of the supply received from the clouds, it would determine the water-level; if less; the level would fluctuate somewhere between this lower point of discharge and the line
A B, in proportion to the amount of rain falling on the exposed portions of the pervious strata.
If a boring be made anywhere through the overlying clay beds, it is evident that the water will rise by hydrostatic pressure until it has attained the same level as in the chalk beds below, and if the surface of the ground at that point be below this level, the water will rise to the surface and overflow as at
G or
H, which it did a few years ago in the
valley of the Thames between
London and Brentford, though it is said that latterly there has been an average fall of about two feet per year in the wells of the
London basin, so that in many of those wells
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Section of the London basin. |
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Well of St. Ouen. |
which formerly overflowed the water is now raised by pumps.
At St. Ouen, in
France, water is brought up from two strata at different levels, the ascending force of the water from the lower stratum being greater than that in the upperThis is effected by means of two pipes, one within the other, with a sufficient interval between them to allow the free passage of water.
The smallest pipe brings up the water from the lower stratum
B to the level of the highest part of the fountain
baa, while the water from the upper stratum, which does not attain so high a level, passes up through the outer pipe to
aa; by this means, should the water from the lower stratum be pure and that from the upper impure, the former may be brought up and discharged separately without being mingled with or contaminated by the former.
Both these streams are used for supplying the canal basin at St. Ouen, which is above the level of the Seine.
The well at
Calais is 1,138 feet, and that at Douchery, in the
Ardennes, France, 1,215 feet, in depth.
The English wells are of less depth, varying from 70 or 80 to 620 feet. The fountains in Trafalgar Square,
London are supplied by wells of this kind, 393 feet deep.
Those of
London are all in the chalk, and it is believed that by deeper boring, so as to reach either the upper or lower green-sand formations, a more ample supply of water could be obtained.
The essential apparatus for boring as generally practiced consists of an auger or borer attached to rods (which are successively screwed on to each other as the work progresses, and which afford a measure for the depth of the boring), and tubes of an exterior diameter equal to that of the well, which are pushed down one after another to prevent the caving in or filling up of the well by earth or rock.
One of the most celebrated artesian wells is that at
Grenelle, a suburb of
Paris, which took nearly seven years and two months of difficult labor to complete; it is 1,802 feet in depth, and when the water-bearing stratum of green-colored sand was reached, the water was discharged at the rate of upwards of 880,000 gallons in 24 hours; the force was such that the water could be carried to a hight of 120 feet above the surface.
The temperature of the water from the depth of 1,802 feet was considerably higher than the mean temperature at the surface.
In the cellars of the
Paris Observatory, at a depth of 94 feet, the thermometer was found constantly to remain at 53°, 06 Fah.; in the chalk, at a depth of 1,319 feet, it marked 76°. 3; in the gault, at 1,657 feet, 79°. 6; and the water flowing from the well has a uniform temperature of 81°. 8, indicating a rate of increase of 1°.7 for each 100 feet below the limit of constant temperature.
The springs which supply the
King's Bath, at
Bath, England, have a temperature of 117°, and the spring of Orense, in Gallicia, has a temperature of 180° Fah.
The artesian Brine-well of Kissingen, in
Bavaria, was begun in 1832, and in 1850 water was reached at 1,878 feet. The depth reached by farther boring was about 2,000 feet. The water has a temperature of 66° Fah., and issues at the rate of 100 cubic feet per minute.
The ejecting force is supposed to be derived from a subterranean atmosphere of carbonic-acid gas, acting with a force of 60 atmospheres.
The tubings are concentric, water rising between the outer and middle tubes, passing down between the middle and inner tubes to the bed of rock salt, where it is saturated, and then raised in the middle tube to the surface.
The artesian well at
Passy, near
Paris, is probably the largest well of the kind that has ever been sunk.
It is carried through the chalk into the lower green sands, which were reached at a depth of 1,913 feet, the bore finishing with a diameter of two feet.
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Six years and nine months were occupied in reaching the water-bearing stratum, when the yield was 3,349,200 gallons per day of 24 hours, subsequently increased to 5,582,000 gallons, and then continued at 3,795,000 gallons per day. The total cost of the well was £ 40,000. It was lined with solid masonry for a depth of 150 feet, then wood and iron tubing was introduced to 1,804 feet from the surface, and below that there was a length of copper pipe pierced with holes.
The variety of boring tools which have been employed in making artesian wells is very great, and the utility of some of those figured and described in works on the subject, if one may be allowed to judge from their shape and appearance, is very questionable.
The mode adopted by the Chinese, who have for many ages been in the habit of boring for salt or fresh water is one of the most primitive.
Their wells are often from 1,500 to 1,800 feet deep, and bored in the solid rock.
A wooden pipe five or six inches in diameter inside is sunk into the earth, and covered with a stone having the same aperture as the pipe.
A steel tool weighing 300 or 400 pounds, concave above and rounded beneath, is suspended by a cord from the extremity of a lever and lowered down the tube; by leaping on the end of the lever, the piece of steel is suddenly elevated about two feet and allowed to fall by its own weight, being partially rotated at each movement.
When three inches of rock have been crushed, the steel is raised by means of a pulley, bringing with it the material which has accumulated on its upper concavity.
Should the attachment of the steel head be broken, another steel head is employed to break the first, an operation perhaps requiring months.
Under favorable circumstances it is said nearly two feet of rock may be penetrated in 24 hours.
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Rock-drill. |
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Well-boring. |
A modification of the above has been employed in
Europe, in which the upper part of the tool is inclosed in a cylinder (see
Fig. 377). These are suspended by a rope, the twisting and untwisting of which imparts a sufficient circular motion.
When the apparatus is withdrawn from the hole, the lower end of the tool closes the bottom aperture of the cylinder, which brings up the mass of comminuted rock to the surface.
A common mode of boring is shown in
Fig. 378. Two men walk around and turn the handle of the boring-tool, which is screwed into an iron rod. In moderately soft ground the weight of the two men and the rotation of the handle will cause the boring-chisel to penetrate, but in rock it requires to be hammered down, the men shifting its position from time to time to enable it to act on a fresh portion of the rock.
This operation is greatly facilitated by suspending the boring-rods from a beam, fixed at one end and worked by a man at the other, assisting by its elasticity the efforts of those below in alternately raising and depressing the tool to give it the necessary pounding motion.
When the hole has by this means been opened as far as the length of the tool will allow, it is withdrawn, and a valved cylindrical anger (
Fig. 379) introduced, which being turned, the valve is opened by the pressure of the comminuted rock or earth below, and fills the cylinder, which is then withdrawn.
See auger, earth-boring.
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Hole-clearer. |
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Rod-claw. |
For raising and lowering the apparatus, a tripod formed by three poles is erected over the mouth of the pit, from which a block and attached tackle is suspended; this is made fast to a claw, represented at
Fig. 380, which is passed under the shoulders of the upper rod. When this is raised sufficiently, a fork is passed under the shoulders of the section below, the upper one is detached by means of a suitable wrench, and the lifting again proceeded with.
Instead of the springing beam, a windlass is sometimes employed for giving the percussive motion to the tool; several turns of the suspending rope being taken around the windlass, the friction of the rope will be sufficient, when aided by the strength of a man having hold of the end of the rope, to prevent it from slipping when the windlass is turned, the man taking up the slack and aiding the upward motion.
When the whole apparatus is raised a short distance in this way, the rope is slacked, and the apparatus falls with its whole weight, penetrating and crushing the rock below.
The windlass is kept constantly in motion in one direction, and the percussive motion is maintained by alternately holding fast and slacking the end of the rope.
In
Fig. 381,
a is a plan and elevation of an auger used for boring in clay or loam.
b is an “S” chisel for hard rock.
c exhibits a hollow valved auger for boring through sand or bringing up rock previously pulverized by the chisel.
d is a spring reamer for enlarging a hole previously bored; this is passed down through the pipe, and, on reaching its bottom, expands to a distance regulated by the screw and swivel connecting the two spring cutters, the cutting edges of which are placed reversely.
Figs. 382 and
383 exhibit different kinds of tools for earth and rock.
The rods frequently break in boring, and for raising the portion broken off below, various devices have been contrived, one of the most simple of which is represented in
Fig. 384. It consists merely of a worm, which screws around the rod, which is only retained by friction when lifting.
This is only available when the weight of the broken part is insufficient to overcome the friction.
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Well-boring tools. |
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Well-boring tools. |
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Well-boring tools. |
The forms of boring and elevating tools which have been employed have been much modified by the experience in boring the oil-wells of the petroleum region.
A great impetus was given to the exercise of ingenuity in this line by the exigencies of this branch of industry; the inventions including boringtools, toolgrabs, tool-jars, derricks, rodcouplings, reamers, welltubes and couplings, tube — packing, “seed-bags,” ejectors, and engines specifically adapted to sinking the shaft and raising the oil.
The boring of the artesian well at
Belcher's Sugar Refinery,
St. Louis, was effected by a simple wedgeshaped drill, the size of which varied according to the diameter of the bore; this drill was screwed to a wrought-iron bar 30 feet long and about 2 1/2 inches diameter, weighing several hundred pounds. To the bar was screwed a pair of slips, so that the drilling was effected by the weight of the bar alone.
To this were fastened the poles, each of which was 30 feet long.
These were screwed together, and were made of two pieces of split hickorywood joined and riveted in the center.
To the last pole was fastened a chain, the other end of which was attached to a spring-beam worked by a steam-engine running with a speed of about 80 revolutions per minute and having 14 inches stroke.
The boring-apparatus was constantly turned by hand-power.
The boring was commenced in the spring of 1849, and continued at intervals till March, 1855.
For performing all the work connected with the boring, the labor of four men was, in general, daily required.
This well was finished at the expiration of 33 months steady work, and attained a depth of 2,197 feet, at a cost of $10,000; that at
Grenelle, 400 feet less in depth, was more than seven years in boring, and is said to have cost about $70,000. From this depth of 2,197 feet the water can be carried to a hight of 75 feet above the surface.
It is a
mineral water, having a salty taste and a strong odor of sulphur, and possesses great medicinal virtues.
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Rod-lifter. |
The well bored at the county buildings of
St. Louis Co., Missouri, has reached a depth of 3,235 feet without obtaining a flow of water.
The artesian wells at
Chicago are 700 feet deep, and discharge about 1,250,000 gallons daily, with a head of 125 feet above the surface of
Lake Michigan.
The water is very pure and cool for the depth from which it comes, having a temperature of 57°.
The well at
Louisville, Kentucky, is even deeper than this, and yields a medicinal water allied in quality to the
Blue Lick and Big-Bone Lick, springs of the same state.
Some years ago a boring was commenced in the public square surrounding the
State House at
Columbus, Ohio, with the intention of endeavoring to obtain a head of water which could be carried to the upper part of that building for its ordinary supply, as well as in case of fire, etc. A depth of rather more than 2,700 feet was penetrated, mostly, if not entirely, through Silurian strata, but none was reached where the water had a sufficient head to rise to the surface.
Artesian wells were made in ancient times in the Oasis of El-Bacharich, and were described by
Olympiodorus, a native of
Thebes, who lived in the fifth century A. D. Their depth is said to be from 200 to 500 cubits, and the water issues at the surface.
They have been noticed by
Arago.
A Frenchman has reopened several of those which had become stopped.
The reopened wells are from 360 to 480 feet deep.
The
Moniteur Algerien gives an interesting report on the newly bored Artesian wells in the
Sahara Desert, in the province of
Constantine.
The first well was bored in the Oasis of Oued-Rir, near Tamerna, by a detachment of the
Foreign Legion, conducted by the engineer,
M. Jus.
The works were begun in May, 1856, and, on the 19th of June, a quantity of water, of 1,060 gallons per minute, and of a temperature of 79° Fah. rushed forth from the bowels of the earth.
The joy of the natives was unbounded; the news of the event spread towards the south with unexampled rapidity.
People came from long distances, in order to see the miracle; the Marabouts, with great solemnity, consecrated the
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newly created well, and gave it the name of “the well of peace.”
The second well, in Temakin, yielded 9 gallons, of 79° temperature, per minute, and from a depth of 279 feet; this well was called “the well of bliss.”
A third experiment, not far from the scene of the second, in the Oasis of Tamelhat, was crowned with the result of 33 gallons of water per minute.
The
Marabouts, after having thanked the soldiers in the presence of the whole population, gave them a banquet, and escorted them in solemn procession to the frontier of the oasis.
In another oasis, that of Sidi-Nached, which had been completely ruined by the drought, the digging of “the well of gratitude” was accompanied by touching scenes.
As soon as the rejoicing outcries of the soldiers had announced the rushing forth of the water, the natives drew near in crowds, plunged themselves into the blessed waves, and the mothers bathed their children therein.
The old
Emir could not master his feelings; tears in his eyes, he fell down upon his knees, and lifted his trembling hands, in order to thank God and the
French.
This yields not less than 1,136 gallons per minute, from a depth of 177 feet. A fifth well has been dug at Oum Thiour, yielding 29 gallons per minute.
Here a part of the tribes of the neighborhood commenced at once the establishment of a village, planting at the same time hundreds of date-palms, and thus giving up their former nomadic life.
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Denture Articulator. |
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Articulator. |
