be saved. In these cases, when drains are made, they should always be cut as narrow as it is possible to

make them, and, after the holes have been formed in them by boring, filled up with loose stones to within about a foot and a half of the surface, which space may be made up by a portion of the earth that had been taken out, putting in turf with the green side to the stones before the earth is thrown in. By this means the water and prejudicial moisture of the peat, or upper soil, may be taken away by the drains, and pass off through the holes that have been formed in their bottoms. But where pits are employed, these should only be filled with small stones to the level of the bottom of the drain, the filling being performed as soon as possible after they are formed. (Anderson's Treatise on Draining, p. 88.) Where there is a chalky stratum below, after taking it out, the flints contained in it may be made use of in this way with much advantage; and where the drains can be carried into quarries, where the stone is much fissured nothing more will be necessary. Where land of this sort is afterwards to be ploughed, great attention should be given to the forming of the ridges and giving them a regular descent towards the main drain, which will contribute greatly to the assistance of the others in conveying off heavy falls of rainwater when they occur.

4244. But a necessary precaution previously to any attempt to drain lands of this kind in the way that has been described, is to ascertain whether the porous stratum under the clay be dry, and capable of receiving the water when let down into it; or already so loaded with moisture itself, as, instead of receiving

more from above, to force up a large quantity to the surface, and thus increase the evil it was intended to remove. This may be the case in many instances, and the substratum contain water which affords no appearances of wetness on the surface, at the place, on account of the compact body of clay that is placed over it, but which, from its being connected with some spring that is higher, may flow up when an opening or passage is given it, either by means of a pit or the auger. In this way a greater quantity of water might be brought to the surface, which, from its being confined by the surrounding banks, would render the ground much more wet than before, and in particular situations produce very great degrees of wetness. When the surrounding high ground declines lower than the bog, though it may be at a considerable distance, by the aid of the level, and the appearance of the surface, the nature of the stratum underneath may, in some degree, be ascertained; and, notwithstanding it may already contain water, a drain may be formed into it to carry off that water, and what may likewise be let down into it from the retentive stratum that lies above it. It must be confessed, however, that cases where surface water can be let down through a retentive stratum to a porous one that will actually carry it off, are very rare. When these occur, it is chiefly in limestone or coal districts, where the surface is hilly or rugged (fig. 630.), and more calculated for

the pursuits of the mineralogist than those of the agricultor.

SECT. III. Draining Hilly Lands.

4245. Draining hilly lands is not in general attended with great expense, as the drains need seldom be covered or filled up, only in such places as may be sufficient for passages for the animals to cross by: and though, where the depth of the trench does not come to the water confined below, it may be necessary to perforate lower, there need not be any fear that the holes will fill up, even where the drain is left open; as the impetuosity of the water itself will remove any sand or mud that may fall into them, where much flood or surface water does not get in. Small openings may, however, be made along the upper side of the trench, in order the more effectually to secure them against any obstructions; and in these the perforations may be made, leaving the mouth of the holes about six inches higher than the bottom of the drain, which will be without the reach of the water that may be collected during the time of heavy rains.

4246. One of the greatest improvements of the hilly sheep-pastures of Holland has been effected by drainage, while the expense is comparatively small. The depth and width of the small ones are only those of the spade. They are usually carried across the face of the hills in a slightly inclined direction, so as to avoid the injury of too rapid a descent after heavy rains; and these small cuts open into a few larger, formed with due regard to the same principle; the whole at last, for an extent of several hundred acres, being led into one still larger, which discharges itself into the nearest rivulet. Improvements of this kind are, perhaps, of greater benefit to the individual proprietors of land who undertake them than any other.

4247. The sides or declivities of many hills, from the irregularity of the disposition of the strata that compose them, are often covered with alternate portions or patches of wet and dry ground. By the general appearance of the surface and the vegetable products that are grown upon it, the nature and direction of the internal strata may frequently be ascertained with so much certainty as to determine the line or direction of a drain without the necessity of examining below the surface of the land. As the ease or difficulty

of draining such grounds depends solely on the position of the different strata of which the hill or elevation may be formed, and upon the erect or slanting direction of the rock, or other retentive body in which the water is contained; where the rock has a slanting or horizontal inclination, the whole of the different springs or outlets, that show themselves on the surface, may originate from or be connected with the same collection or body of water, and may be all drained and dried up by cutting off, or letting out, the main body of water, by which they are supplied, at the inferior part of the reservoir, or that part where the water would of its own accord readily run off if it were not confined beneath an impervious covering of clay or some other material.

4248. But in cases where the rock lies in an erect or perpendicular form, and contains only partial collections of water, in some of the more open cracks or fissures of the stone, which discharge themselves at various openings or outlets that have not the least connection with each other, it would be an idle and fruitless endeavour to attempt the cutting of them off by means of one drain (fig. 631. a), or by boring into any one of them in

631

particular, without cutting a drain into each (a, b, c). In this case it is more advisable to make the main drain wholly in the clay, with small cuts made up to each outlet, than along the place where the springs burst out; as in that line of direction it would be

too much in the rock, and consequently be extremely difficult to cut, on account of the nature and disposition of the stone. When the water passing out on the line of the springs can be found by the auger in the main drain, at the point of junction, it will be the more completely cut off; but where this is not practicable, the depth of the small cuts may reduce it to such a level as will prevent its flowing over and injuring the surface of the land below it.

4249. In such hills as are constituted of alternate strata of rock, sand, and clay, the surface of the last may frequently be wet and swamp, while that of the sand is dry, and capable of producing good crops of grass; in all such cases, in order to drain the land completely, as many cuts will be necessary as there may happen to be divisions of wet and dry soil. The summit, or most elevated part of such hills, being mostly formed of loose porous materials, the rain and other water descends through it till its passage becomes obstructed by some impervious bed or stratum, such as clay, when it is forced up to the surface, and runs or oozes over the obstructing stratum; after having overflowed the upper clay surface, it is immediately absorbed and taken up by the succeeding porous one, and, sinking into it in the same way as before, passes out again at the lower side, rendering the surface of the next clayey bed prejudicially wet, as it had done that of the first. In this way the same spring may affect all the other strata of the same kind, from the highest part down the whole of the declivity, and produce in the bason, or hollow at the bottom, a lake or bog, should there not happen to be a passage or opening to take away the water. In order effectually to drain hills of this kind, it will be most advisable to begin by forming a trench along the upper side of the uppermost rushy soil, by which means the highest spring may be cut off; but as the rain and other water that may come upon the next portion of porous soil may sink down through it to the lowest part, and produce another spring, a second cut must be made in that part, to prevent the water from affecting the surface of the succeeding clayey bed. Similar cuts must be formed so far down the declivity as the same springs continue in the same way to injure the land, and in some cases a sufficiency of water may probably be obtained to irrigate the land below, or for some other useful purpose.

SECT. IV. Methods of draining Mixed Soils.

4250. Where the soil is of a mixed and varied nature, but the most prevailing parts of the clayey kind, the business of draining is considerably more tedious and difficult than where the superficial and internal parts have greater regularity. In such lands, as the collections of water are completely separated by the intervening beds of clay, each becomes so much increased in the time of heavy rains, as to rise to the level of the surrounding surface; when the water, finding a free passage, as it would over the edges of a bowl, overflows and saturates the surface of that bed of clay, rendering it so wet and sour that its produce becomes annually more scanty, and the soil itself more sterile and unproductive.

4251. From the sand-beds (fig. 632. a, a, a) in such cases having no communication with each other, it must evidently require as many drains (b, b, b) as there are beds of this kind, in order fully to draw off the water from each of them. A drain or trench is

to be drained (c), up to the highest and most distant sandbank (d), in such a line of direction as, if possible, to pass through some of the intermediate sand-beds, and prevent the labour and expense of making longer cuts on the sides, which would otherwise. be requisite.

4252. Where the different beds of sand and clay are of less extent, and lie together with greater regularity, they can be drained in a more easy manner with less cutting, and of course at less expense. Below the layers or beds of sand and clay that lie, in this manner, alternately together, and nearly parallel to each other, is generally a body of impervious clay, which keeps up the water contained in the sand, which sand being constantly full, the adjacent clay is thereby rendered moist, and in wet seasons the water runs or trickles over it. As in these cases, the principal under-stratum of clay is rarely more than four or five feet below the surface, it is advisable to cut a drain (fig. 633. a)

633

to that depth through the middle of the field, if it have a descent from both sides; but if it decline all to one side, the drain must be made on that side (b), as the water will more readily discharge itself into it; and, unless the field be of great extent, and have more than one depression or hollow in it, one drain may be quite sufficient for the purpose, as by crossing the different beds that retain the water, it must take it off from each. 4253. A principal difficulty in draining ground of this nature, and which renders it

634

impracticable by one drain, is when the direction of the alternate layers, or beds of clay and sand, lies across the declivity of the land (fig. 634. a, a), so that one drain can be of no other service than that of conveying away the water after it has passed over the different strata, and would naturally stagnate in the lowest part of the field, if there were no other passage for it. Where the land lies in this way, which is frequently the case, it will therefore be necessary, besides the drain in the lowest part (b), to have others cut up from it in a slanting direction across the declivity (c, c), which, by crossing the different veins, or narrow strata of sand (d, d, d), may be capable of drawing the water from each of them.

4254. In forming the drains in these cases, it is recommended that, after laying the bottom in the manner of a sough, or in the way of a triangle, it be filled some way up with small stones, tough sods with the green side downwards being placed upon them before the mould is filled in. But where stones cannot be readily procured, faggots may be employed, the under part of the drain being laid, or coupled, with stones, so as to form a channel for the conveyance of the water that may sink through the faggots, and for the purpose of rendering them more durable; as, where the water cannot get freely off, which is generally the case where there is not an open passage made of some solid material, it must, by its stagnation, soon destroy the faggots, and choke up the drain,

4255. The estate of Spottiswoode in Berwickshire affords an interesting example of successful drainage of mixed soil and strata. It was begun in 1815, under the direction of Mr. Stephens, an eminent draining engineer, and author of a useful work on the subject (The Practical Irrigator, &c., Edin. 8vo. 1829); and eighteen miles and a half of drains, some parts of which were thirteen feet deep, but the medium depth of which was from five to seven feet, had, in 1820, rendered between five and six hundred acres of land most valuable, which had been before of little value.

4256. The grounds to be drained at Spottiswoode "consisted of a soil of various depth, under which commonly lay a stratum of clay from two to three feet deep, then a thin bed of sandy or gravelly substance, of a foot deep, or more, containing water; after that another bed of clay, of two or more feet deep; and lastly, a bed of sand, gravel, or slaty rock, containing the larger quantity of water. Upon reaching the

lower of these porous strata, the water disappeared in the upper one: and hence generally the expediency of not stopping at the first, but of working down till the main stratum was reached. Several instances occurred where the strata lay too deep to be reached by a drain; in which cases it was deemed necessary to sink wells or pits at certain distances along the line of the drain, from ten to eighteen feet deep, or order to reach the open strata, so that the water, rising through the wells to the bottom of the drains, might be conveyed away without reaching the surface. It was never thought sufficient to have reached the first seam containing water, unless it were at the depth of four feet or more, and evidently appeared to be that containing the main body of water which occasioned the wetness of the surface." (Trans. Hight. Soc.) 4257. The first operation in the process of draining "was to ascertain the depth and nature of the strata in which the water was contained, and the overflowing of which, where no outlet existed, produced, as was before remarked, either springs or bursts of water, or a general oozing. Along the line of these springs, or in the upper part of the wet ground, pits were sunk in various places. The place of each being marked out, a man was sent to dig each pit, breaking the ground nearly in the direction of the intended drain, six feet long and three feet wide, which is sufficient space to allow a man, or sometimes two, to work freely. The earth was then thrown to the lowest side, and well off from the pit, to prevent the sides from breaking in: these pits were made to the depth of five or six feet, or to a greater depth if necessary, according to the nature of the ground, or until the bed of sand, gravel, or rock, which contained the water, was reached. Sometimes it became necessary, after having gone as deep as a man could work, and when no water appeared, to bore down with boring-rods, in order to ascertain at what depth the stra tum containing the water lay. In some instances, where the surface was wet from a general oozing, and no regular spring appeared, it became necessary to go down to the depth of thirteen feet, when, in breaking through a thin cake of freestone, not above an inch in thickness, the water burst up, and filled the pit to the brim in the following morning. This species of examination prevents the working at random in laying out the lines of drains, affords data for judging of the depth and dimensions to which they should be formed; and, by giving a knowledge of the substances to be dug through, enables one to enter into contracts with the workmen with greater certainty." (Trans. Highl. Soc.)

635

4258. A general idea being thus obtained of the ground to be drained, and men employed to sink the pits, the next operation is to mark out these lines on the ground. In doing this, a hand sketch (fig. 635.) indicating the direction of the drains and their depth will be found useful. "On the ground, the lines may be marked in various ways. When the land is in grass, a plough may be made to follow the director, as he walks deliberately along his intended line, a man leading the horses by the head, if necessary, and walking between them. If it is inconvenient to use a plough, the lines may be marked by pins, or small pits, a spade's breadth square, made at convenient distances, by cutting out a turf clean by four cuts of a spade, and laying it upside down at the side of the

hole, in the line of the drain." The drains were next dug out, and formed; some of them three feet wide at the top, six feet deep, and two feet wide at bottom, and others of different widths and depths, but generally in the same proportion. The following are Mr. Stephens's directions for building:

4259. The side walls of the drain, supposing it to be six feet deep, and two feet wide at bottom," must be well built with dry stone, all laid on the proper bed (and not set up edgeways), nine inches thick by six inches high, forming an aperture of six inches square, the covers for which must be sufficiently strong to sustain the pressure of the incumbent weight of stone and earth; and should project, at least, three inches over the inside of each side wall,-two feet of stone must be well packed above the cover of the aperture. The first foot of stone above the cover of the aperture may be put into the drains from three to four pounds weight, the upper part must be broken as small as common road-metal, and should be made

636

quite smooth or level, so that every part of the drains may have an equal depth or thickness of stone. A thin covering of straw should be laid on the top of the broken stones, to prevent the loose earth from falling through the aperture of the drains. The drains may be then filled with earth, nine inches above the natural level of the surface of the ground. Wells must be sunk along the lowest side of the lines of drains, in every place where the above mentioned depth of six feet does not reach the porous bed that contains water. These wells may be made from five to six feet square, or sufficiently wide to allow a person to work with freedom; and must be sunk through the impervious strata into the pervious stratum of sand, gravel, or rock, where the water flows freely. The wells may then be filled with small clean stones, thrown in promiscuously, till the stones in the wells come in contact with the stones in the drains. The upper part of the wells above the level of the stones in the drains may be filled with earth." (fig. 636.) (Trans. Highl. Soc. vol. vii. p. 222.)

4260. The stones of which the drains at the bottom of the conduit are to be built, and with which the drain is afterwards to be filled to the depth of two feet or more, as is shown above, should be laid down on the upper side of the line, as near to it as possible, that they may be the more easily handed in. They are laid on the upper side, for the convenience of throwing out the earth on the lower side. It is very desirable that the stones should be, if possible, laid down before the drain is begun to be dug, as it is often necessary to build and fill it as fast as it is dug, to prevent the sides from falling in, which, when it occurs, occasions a very great deal of extra work, and the drains themselves are never so well constructed. This most frequently happens in ground under tillage, the sides being more tender than when in grass, where the turf is the means of preserving the sides from the pressure of the earth thrown out, and of the stones laid down. When the sides are evidently likely to fall in before the drain can be built, they may be kept up for a time by a board laid flat to each side of the drain near the top, and cross sticks put in to keep the boards asunder. Circumstances frequently occur, which prevent the stones from being laid down beforehand, and they are then brought forward as the work of cutting the drain is going on. Under the eye of an intelligent and attentive director, this may be done without danger; but, even then, unforeseen occurrences sometimes prevent the possibility of getting the materials forward for several days; and if any rainy wea ther intervene, and the drains are in a clayey soil, there is a certainty of slips and falls, occasioning much extra labour, and requiring, in consequence of the additional breadth of the drain, a much larger quantity of stones to fill the opening. Where a piece of drain seems likely to fall in, it should always, if possible, be built and filled before night, or the sides kept asunder by means of boards, as before mentioned," (Trans. Highl. Soc. vol. vii.)

4261. Drains may be dug, and, when built, the earth may be filled in by contract "The conduit is built in the work; but in general day work is to be preferred.

who, by practice, is equally competent; this person always working at daily wages, to prevent him from having any interest in hurrying over this most important part of the operation."

4262. The drains may be cut only "two feet wide, with the sides perfectly perpendicular, provided that, from the tenacity or hardness of the substances dug through, the sides will stand till the stones are put in. It is usual, however, to break the ground somewhat wider at the top, and so to give it a slight slope to the bottom. The work of cutting is always done by contract at so much per rood or yard, and several labourers generally join in making one drain, and arrange the work among themselves. The casting or cutting, it is scarcely necessary to observe, is always commenced by the workmen at the lower end, and worked upwards to the higher ground, and never downwards. They usually begin by working about two feet deep in the first instance, several roods in length, then going over the ground again, deepening it to four or five feet, and afterwards going over it the last time, and finishing the bottom, by making it perfectly level and ready for the mason to build the conduit in the bottom. The bottom must, for this purpose, be completely two feet wide, though, when free-stone is employed, the width may be less." (Trans. - Highl. Soc.)

4263. In building the drain," the mason has an assistant, generally a female, at the top, who hands him the stones he requires. He begins with small flat stones to build the wall on each side of the bottom of the drain, nine inches broad, and six inches high, so as to leave six inches for the conduit in the middle. This he does roughly, but in such a manner that the stones shall be laid solidly on one another. When the ground at the bottom is solid, either dry gravel, or clay, or rock, the mason's foot, with his ordinary clog or shoe, standing in the centre, is the measure of the width of the conduit. When the land is inclined to be wet and soft, a plank six inches broad is used for him to stand upon. When the bottom is a wet spongy clay, or sand of the nature of a quicksand, or very soft, it is often necessary to flag the bottom of the conduit with very thin stones or slates." (Trans. Highl. Soc. vol. vii.)

4264. When a perfect quagmire has been met with, "which has happened chiefly in red clay, the faster the wet clay has been thrown out, the faster it has boiled up from below. In these cases, it has been found necessary to lay planks on the bottom of the drain, and build upon them. But this will very seldom be necessary where proper precautions are used. On first meeting with quagmires of this kind, attempts were made to dig them out; for which purpose a strong wooden frame was made, large enough for four men to work in with freedom, composed of different pieces, so that the work men might add to the sides of the frame as they worked downwards. Notwithstanding the frame's being made very strong, the pressure became so great, that the sides came together, and stopped the operation. The consequence was, that, after great labour and active exertion in taking out large quantities of wet clay, which thus continued to boil up (but the very taking out of which undermined the banks from beneath), the sides of the drain fell in masses, and made great gaps, which increased the longer the work was carried on. In these circumstances, it became necessary to use planks to build the conduit, and to fill in the stones as fast as possible, by employing a great number of persons at once. The weight of these superincumbent stones then kept the planks and conduit at their proper place, so much so that the worst of these parts never exhibited any symptom of imperfection, though made ten years ago. On all occasions afterwards, however, when any of these quagmires were found, the process of taking out the bottom of the drain was followed, yard by yard, by flagging the bottom, building the conduit, covering it, and filling the stones over it; and in this way the quagmire was prevented, by the immediate pressure from above, from boiling up. It never failed to be seen that the longer these operations were delayed, the softer and more intractable the interior of the drain became. After building the side walls for a yard or two in length, the mason, according to circumstances, cleans out the conduit with a narrow hoe, and then covers it with such large broad stones as he can procure, from fifteen inches in length to two feet, being the utmost width of the drain itself. These are handed down carefully to him by his attendant; and, after he has laid three or four of them, he takes smaller flat stones, as the larger are always uneven at the edges, and covers every interstice; and afterwards, with similar stones, packs carefully the ends of the covers, before finishing any particular portion of the work so as to prevent them from shifting; and still further to cover every hole through which any thing might be carried into the conduit, he has a rolled up wisp of straw which he puts in the mouth of the conduit, which allows the water to pass out, but prevents mud and sand from getting in. His attendant then throws the remainder of the stones in promiscuously to the depth of two feet, or sometimes more, if the materials are plentiful, and particularly where there are two seams con