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feet; that at Wilhelmshohe, in Hesse Cassel, 190 feet, but this fountain is now out of order. The most remarkable fountain in the world is probably the Emperor Fountain at Chatsworth, so named by the Duke of Devonshire in honour of the visit of the Emperur of Russia to this country, a few years ago. This fountain plays to the height of 267 feet; and it is expected, when the reservoir is quite full, to raise it to the height of 280 feet. Fig. 64 (p. 73) represents this fountain in action. For the purpose of supplying it, a new reservoir was constructed, and a conduit or drain cut to convey water into it. This drain commences at Humberley Brook, near one of the bridges on the Chesterfield road, and is increased by tributary springs from the moors, passing along with a gentle fall to the reservoir, for two miles and a half, and winding round a hill in serpentine forms to the proper level. The reservoir covers eight acres of ground; its average depth is about 7 feet; its greatest depth at the head is 13 feet, where there is a solid mass of masonry with a deep valve, to let the water off and on. There is also a waste-pipe for the surplus water. The first length of piping from the reservoir towards the fountain is on the top of the hill, where the ground is comparatively level: this length is 270 feet; the pipe is of 15-inch bore, and the metal three-quarters of an inch thick. The middle length is 1,386 feet; 15-inch bore, and 1 inch metal. The lower length is 959 feet; 15-inch bore, and 1| inch metal: making altogether 2,621 feet, or 873 yards, 2 feet. At the distance of 181 feet from the fountain is a double-acting valve, which takes about five minutes to open or shut fairly, so that the whole may never be let on or off with a shock to the pipes. For a short distance from the fountain the pipe is 1^ inch thick in the metal, and is secured by a saddle-plate and bracket cast solid to the pipe, and is firmly bolted to a mass of masonry. The end of this large pipe turns up with an elbow, and terminates with a flange, to which the conical tapering part of the jet is fixed. This conical part is about 7 feet high, and terminates in a brass nozzle. Different funnels and nozzles are used, to give variety to the form of the water jet. There are 298 joints in the piping, turned and bored with dip sockets round each, and the weight of the metal in the pipes is about 217 tons. The whole fall of pipe from the reservoir to the fountain is 381 feet, but not of uniform declivity; for the first 450 feet the fall is 1 in 40; for the next 200 feet the fall is very steep, it being 1 in 2; for the next 800 feet it is 1 in 5; and for the remainder 1 in 9.

Bearing in mind the simple but important principle upon which artificial fountains depend, the reader will understand the mode of formation in natural fountains. It is only on the slopes of hills or at their summits that the beds of the stratified series of rocks crop out or are exposed on edge; here it is that the rain-water penetrates and fills the elevated mountain cisterns or hilly reservoirs: these watercarrying beds, after having descended along the sides of the hills, which formerly broke them up while they elevated them, extend horizontally or nearly so along

the plains, and in the plains they are often imprisoned as it were between two impermeable or water-tight beds of clay or of hard rock; and thus we may readily conceive the occurrence of subterranean waters in the same hydrostatic condition as the pipes of the fountains just noticed, so that by sinking a pit in the valleys through the upper strata down to the more elevated of the two impermeable beds, between which the water is confined, we thus provide as it were the second branch of pipe, in the form of the U already noticed, or the jet of the fountain at Chatsworth, and the water will rise in this pipe or jet to a height corresponding to that which the water maintains on the side of the hill when it begins to descend. Hence, in any horizontal plane, the different subterranean waters at different elevations may have different powers of ascending: in one place the same water may be projected to a great height, and in another rise no higher than the surface of the soiL All the variations which are met with, arise simply from inequalities of level.

But some of these natural fountains, such as those of Lillers in Artois, throw up their waters in the midst of immense plains, where no hill, not even a hillock, is to be seen in any direction. In such a case, the hydrostatic columns are to be sought for some miles off, hundreds if necessary. The existence of a watery subterranean communication 300 miles in extent, is no objection when 300 miles of country have the same geological constitution. Even at the bottom of the ocean, springs of fresh water project vertically to the very surface. This water evidently proceeds from the land by natural channels, which rise higher than the surface of the sea. On one occasion when Buchanan was becalmed in the Indian ocean, he discovered an abundant spring of fresh water, at the distance of 125 miles from Chittagong, and 100 miles from the neighbouring coast of the Sunderbunds.

These remarks will receive further illustration from the following diagram, Fig. 67. Suppose a basin, composed of permeable strata EFG alternating with impermeable strata HI KL, to have the margin of all these strata continuous in all directions at one uniformly horizontal level AB; the water which falls in rain upon the extremities of the strata EFG, would accumulate within them, and fill all their interstices with water, up to the line AB; and if a pipe were passed down through the upper into either of the lower strata, at any point within the circumference of this basin, the water would rise within it to the

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regular never exists in nature; the extremities or outerops of each stratum are usually at different levels, a, c, e,g. In such cases the line a b represents the water-level within the stratum G; below this line, water would be permanently present in G; it sould never rise above it, for it would be relieved by springs that would overflow at a. The line c d represents the level above which the water could never rise in the stratum F; and the line ef represents the highest water level within the stratum E, the discharge of all rain waters that percolated the strata EFG, being thus effected by overflowmg at e, e, a. If common wells were sunk from the surface it I, into the strata GFE, the water would rise within them only to the horizontal lines ab, ed, ef. The upper porous stratum C, also, would be permanently loaded with water below the horizontal line g h, and permanently dry above it.

The following section is intended to explain the rise of water in artesian wells in the London basin, from permeable strata in the plastic clay formation and subjacent chalk. The water in all these strata, as already explained, is derived from the rain which falls on those portions of their surface that are not covered by the London clay, and is upheld by clay beds of the gault beneath the chalk and fire-stone. Thus admitted and sustained, it accumulates in the joints

and crevices of these strata, to the line BA, at which it overflows by springs, in valleys, such as that represented at C. Below this line all the permeable strata must be permanently filled with a subterranean sheet of water, except where faults or other disturbing causes afford local sources of relief. Where such do not interfere, the horizontal line B A represents the level to which water would rise by hydrostatic pressure in any perforations through the London clay, either into sandy beds of the plastic clay formation, or into the chalk; such as those represented at DEFGHI. If the perforation be made at G or H, where the surface of the country is below the line BA, the water will rise in a perpetually flowing artesian fountain, as it does in the valley of the Thames between Brentford and London.

In proportion as the number of Artesian wells is increased, the height to which the water ascends in each becomes diminished, and the general application of them would discharge the subterranean water so much more rapidly than it arises through the interstices of the chalk, that fountains of this kind would soon cease to overflow, although the water within them would rise and maintain its level at the surface of the land. At Brentford there arc many wells which continually overflow their orifices, which arc only a few feet above the level of the Thames. In

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Ibe London wells, the water rises to a less level than in those at Brentford, and it is by no means certain that an adequate supply of water for the whole of London could be obtained by boring, as has been proposed. The water which supplies the fountains of Trafalgar Square, rises only to within about 16 feet of the surface, and it is pumped up by a steam engine, into reservoirs at the back of the National Gallery. After supplying the fountains, the water goes to supply some of the public offices in the neighbourhood of the Horse Guards, and the remainder is returned into a reservoir connected with tbc steam engine, so that it can be pumped up and used a second time if necessary.

The mode of action of an Artesian well will be

understood from the section, Fig. 69, representing a double fountain at St.Oucn, which brings up water from two water-bearing strata at different levels below the surface of the soil E. In this double fountain Hie ascending forces of the water in the two strata A and B are different; the water from the lower stratum B, rising to the highest level b"; that from the upper stratum A, rising only to a'. The water from both strata is thus brought to the surface by one bore hole, of sufficient size to contain a double pipe, viz. a smaller pipe inclnded within the larger one, with an interval between them for the passage of water; thus, the smaller pipe b, brings up the water of the lower stratum B, to the highest level of the fountain b"; whilst the larger pipe a, brings up water from

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But where a single pipe is used, as is generally the case, if the boring penetrates a bed containing impure water, it is continued deeper until it arrives at another stratum containing pure water; the bottom of the pipe being plunged into this pure water, it ascends within it, and is conducted to the surface through whatever impurities may exist in the superior strata. The impure water is exclnded by the pipe from mixing with the pure water ascending from below.

One of the most remarkable Artesian wells of our own time is that of Grcnelle, in the Paris basin. It was undertaken in 1834, up to which time no successful artesian sinking had reached a greater depth than about 1,000 feet. It was caleulated that after passing through the tertiary beds, and the chalk, the upper greensand would be reached at a depth of 1,200 or 1,500 feet. Operations were commenced with an auger of unusual dimensions, viz. 1 foot in diameter; the borings brought up, in succession, the alluvial soil and subsoil, and the tertiary sands, gravels, clays, lignite, &c., until the chalk was reached. They then bored through the hard upper chalk down to the lower chalk with green grains; the dimensions of the auger being reduced at 500 feet to !) inches in diameter; at 1,100 feet, to 7£ inches; and at 1,300 feet, to 6 inches in diameter. In the course of these borings, numerous accidents occurred. In May, 1837, at the depth of 418 yards, the hollowtube with nearly 90 yards of the boring rods attached to it broke, and fell to the bottom of the hole, and fifteen months were occupied in extracting the broken

fragments, of course delaying the work for that period. In April, 1840, in passing through the cludk, the chisel attached to the boring-rod fell off, and several months were occupied in recovering it. A similar accident occurred a second time, but instead of attempting to recover it, it was driven into the stratum, which happened to be gravel. When the caleulated depth of 1,500 feet had been reached without any result, the Government became disheartened, and the public patience exhausted. On the urgent representation of M. Arago, the sinkings were continued, until at length, on the 26th of February, 1841, the rod snddenly descended several yards. They had pierced the vault of the subterranean waters, and in the course of a few hours the water rushed up violently from a depth of 1,800 feet. The first rush brought up an immense volume of water mixed with sand and mnd, and at a high temperature. It rose many feet above the surface, and the force was so great that considerable injury was done to the boring rods, and it was some time before the shaft could be sufficiently cleared for the full discharge to issue without interruption. The pipe by which the water reached the surface was carried to a height nearly on a level with the source of the supply. The pipe as it rose from the ground, and the scaffolding which supported it, are shown in Fig. 70, where the water is represented flowing into a circular iron reservoir, from which it was conveyed by

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another pipe to the ground. Since the tubes have been completed, about half a million of gallons of perfectly limpid water have been supplied by tins well in the course of the twenty-four hours, at the constant temperature of 82° Fahr.

The temperature of the water of Artesian wells is always higher than that of the surface, according to Arago, in the ratio of 2° for every 00 or 80 feet of descent; but according to the observations of Dr. Paterson on eleven Artesian wells in Scotland, the mean increase is 1° for every 48 feet of descent; and the mean of seventeen wells in other places gave 1° for every 53 feet of descent. In one observation the temperature of the well water was 52°, while that of the surface of a spring close by was at the freezing point.

Artesian wells have been sunk to various depths. The greatest depth is that of Grenclle just noticed. The seventh sheet of water found near St. Nicholas d'Aliermont already alluded to, was at the depth of 1,030 feet, and the water rose from it to the surface. As it was not water but coal that was sought for the works were abandoned, but a copious fountain was unintentionally formed, the waters of which issue from a souree more than 1,000 feet deep. In the Duke of Northumberland's grounds, at Syon, is an Artesian boring 535 feet deep. The borings passed first through loose gravel and sand, and strong blue clay, to the depth of 410 feet; then through 10 feet of green sand; next through 30 or 40 feet of loose chalk; and lastly into firm, hard chalk. This well rises 5 feet above the surface.1

As to the quantity of water from Artesian wells, the supply appears to be in most cases continuous and abundant. In the monastery of St. Andre, two miles from Aire, in Artois, a fountain has continued for considerably more than a century to rise to the height of 11 feet above ground, and to supply nearly 2 tons of water per minute. At Bages, near Perpignan, is a well which furnishes 333 gallons per minute. One at Tours jets 6 feet above ground, and yields 237 gallons per minute;* and at Merton in Surrey is a well which supplies 200 gallons per minute. At Southampton there is an Artesian well which overflows to the height of 5 feet, and yields 10 gallons per minute. At the depth of 100 feet, it supplies to the pumps 48 gallons per minute. The water is from the sandy stratum in the tertiary formations that overlie the chalk which forms the foundation of the geological basin in which Southampton stands. At Brighton, in 1842, a well bored in the chalk to the depth of only 97 feet, gave by pumping with steam, 700 gallons of water per minute. In some cases, the supply of water has been so abundant as to lead to inconvenience. Thus, a case is mentioned in the Bibliolhique Unicerielle de Genece, of an Artesian boring in a garden to the depth of 360 feet, and 4.5 inches in diameter, in which the first discharge of water was so copious as to overflow the whole yard round the house, and to submerge the adjacent cellars. The damage was so great that the neighbours lodged a complaint, and

fl) One of the first Artesian wells near London was bored in 17l11, at Norland House, on the north-west of Holland House. The water was obtained from the sandy strata of the plastic clay formation, but so much obstruction accompanied the admission of water to the pipes from this formation, that it was found more convenient to pass lower down through these sandy strata, and obtain the water from the subjacent chalk.

(2) The water from these wells rushes up with so much foree, that a cannon ball placed in the pipe is violently ejected by the ascending stream.

the police interfered. Two or three men attempted to close the bore with a wooden and afterwards with an iron plug, but they were driven back by the violence of the water. A mason then planted several tubes of small diameter over the bore, and thus succeeded in mastering the water.

Artesiau wells have not only been employed for providing houses with water, but their waters have also been used as a moving power. In the village of Gonelicm near Bethune, there are 4 borings to the depth of 120 feet: the waters are conveyed into the watereourse of a flour mill, and are also made to subserve other agricultural purposes. The little town of Roubaix near Arras, was in danger of losing its principal means of support, viz. its silk spinning and dye works, from want of water. Artesian wells were sunk, one of which yields 288 cubic yards of water per day, or double the power of a steam engine of 20 horse power. At Tours, an Artesian well pours 237 gallons of water per minute into the trougn of a water-wheel 21 feet in diameter, which is the moving power of a large silk manufactory. In another case, at Fontes near Aire, the united waters of 10 wells are made to turn the mill-stones of a large mill, to blow the bellows and to beat the hammers of a nail manufactory.

The constant high temperature of these waters renders them especially valuable during winter, either as a moving power or as a means of thawing and washing away the ice which impedes the motion of waterwheels in time of frost. In "VVurtemburg, the water of several Artesian wells is transmitted through metal pipes arranged in large manufactories, and thus a constant temperature of 47° is maintained at a season when the external temperature is at zero. Greenhouses have been heated in a similar manner, and the Artesian waters of Grenelle have been applied as a souree of warmth to hospitals and other public buildings. By introducing the water of Artesian wells into fish-ponds, the extreme variations of the seasons have been prevented. Artificial cress plots have also been formed and supplied by means of these wells with pure water of a steady temperature. The artificial cress plots of Erfurt product a large annual revenue. Paper mills have also been supplied with the pure water of these wells at periods when heavy rains have made the river water muddy. In the Department du Nord the fine line used in the manufacture of cambrie, lawn, lace, &c., is prepared from flax retted in pools which are supplied by Artesian waters: by their purity and invariable temperature, the soluble portions of the flax are more quickly removed and the valuable qualities of the filaments retained in high perfection.

Such are a few of the advantages and practical applications of Artesian wells. They are most available and of the greatest use for domestic purposes in low and level districts, where water cannot be obtained from superficial springs, or by wells of ordinary depth. .Artesian borings called Blow-wells have long been known on the east coast of Lincolnshire, in the low chalk district between the wolds of chalk, near Louth and the Wash. These districts were without springs until it was discovered that by boring through the clay to the subjacent chalk, a fountain might be obtained which would flow incessantly to the height of several feet above the surface. It has even been supposed that by means of Artesian borings, water may be raised to the surface in the sandy deserts of Africa and Asia; and it is in contemplation to construct a series of these wells along the main road which crosses the Isthmus of Suez.

But if Artesian borings have been in the majority of cases successful, it must not be forgotten that failures do sometimes occur. Thus at Blingcl in the valley of Ternoise, three borings were made in 1820; the first became a very beautiful projecting fountain; the other two, very near to the first, gave no water. At Bethune, a boring after having piereed 70 feet of alluvial soil and 30 feet of limestone, brought to the surface a beautiful limpid jet of water. In the garden of the contiguous property, a similar operation of boring produced no water even though the chalk had been penetrated more than 100 feet.

Such cases as these are by no means rare; and M. Arago explains these failures in the following manner: —It must be remembered that these subterranean waters do not form sheets of great extent, and even do not form sheets at all, except at the surface of separation of two distinct mineral beds. On the contrary, in the thickness of those of the beds which are least compact, as in the case of chalk, the water neither exists in any certain defined limits, nor circulates except in trenches between which are found masses of chalk without fissures and hence impermeable. If the bore enters one of these trenches, water will gush up more or less according to the pressure it there sustains; but should the boring be carried on in a very compact portion of chalk, the labour will be lost. If however the bore be carried to the impermeable bed upon which this mass rests, then there would be found not only streamlets and liquid trenches but a plentiful reservoir, and the success of the operation would be complete.

Artesian wells are sometimes curiously affected by the tides. In the Artesian well of the palace of the Bishop of London at Fulham, which is bored to the depth of about 300 feet, the quantity of water is 80 or 60 gallons per minute, according as the tide is high or low. M. Arago explains the effect in cases of this kind, by supposing the subterranean river which feeds the well, also partially to discharge itself into the sea or into a tidal river by an opening of considerable dimensions compared with its own size. If this opening be diminished the pressure will immediately increase at all points of the natural or artificial channels occupied by the subterranean waters, and the flow by the well will become more rapid, or what is the same thing, the level of the water will rise. The flow of the rising tide immediately above the opening by which the subterranean waters discharge themselves, will increase the pressure upon the opening, the effect of which will be similar to that of diminishing its size, so that a less quantity of water will

escape into the tidal river. When, on the contrary, the tide is ebbing, the pressure will be diminished and an increased quantity of water will flow from the subterranean courses. Hence it will be readily seen that the flowing and ebbing of the tide must produw a corresponding flowing and ebbing of the w ater of the well.

There is a description of boring or sinking which M. Arago terms negatice Artesian Kelts or drain-wells. These are pits sunk for the purpose of transmitting into the earth, water retained at the surface by strata of impermeable clay or stone, thereby rendering extensive districts mere morasses unfit for cultivation. Thus the Plain of Faluns near Marseilles was formerly a great morass which it appeared impossible to drain by surface channels. King Rene sunk numerous drain-wells which proved effectual, and the waters thus carried off are said to have formed the projecting fountains of the port of Mion near Cassis. The river Orbe in the Jura which descends from the lake of the Rousses, conveys into lake Joux much more water than is removed from it by evaporation. This latter lake, which has no river issuing from it, nevertheless maintains a nearly uniform elevation. "It is," says Saussure, "because nature has provided for these waters subterranean issues by which they are engulfed and disappear. As it is of the greatest consequence for the inhabitants of this valley to preserve these natural drains, without which their arable lands and habitations would be immediately overflowed, they preserve them with the greatest possible care; and when they pereeive that they do not take off the water with sufficient velocity, they themselves open new ones. For which purpose all that is necessary is to sink a pit 15 or 20 feet deep, and about 10 feet in diameter in the thin and vertical strata, the summits of which appear on the surface. The waters absorbed by these entonnoirs, or funnels, as they are called, are observed to rise from the earth and form a large spring, called Orbe, at the distance of two miles below the southern extremity of the lake." In this passage of two miles the absorbed waters descend 680 feet.

In the winter of 1832-3 a manufacturer of potatostareh at Villetaucuse, a small village about three miles from St. Denis, sunk a pit to the depth of the absorbing stratified beds, and thus got rid of no less than 16,000 gallons of impure water per day, the stench of which had given rise to serious complaints which would probably have compelled him to break up his establishment. After six months of daily absorption, nothing but sand was found at the bottom of the pit, so completely had the nuisance been removed by this means. It is to be feared, however, that the water of neighbouring wells might be injured.

The mechanical details connected with the formation of Artesian Wells, will be found under Bonixc. Numerous sourees of information have been referred to in the preparation of this article, but the editor wishes specially to acknowledge M. Arago's notice in the Anniutire for the year 1835, and Dr. Buckland's Bridycwater Treatise. The method of sinking common weDs will be found under the article Wells.

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