Domestic Encyclopædia (1802)/Draining
DRAINING is the art or practice of making artificial channels, for carrying off superfluous moisture or water from wet or marshy lands.
This highly useful art did not generally engage the attention of agriculturists, till about the middle of last century. It was formerly practised by persons, called undertakers, who received one-third of the drained land as a recompense. The advantages to be derived from their labours being obvious, several public-spirited men of talent have lately, with considerable success, investigated the subject; and with great exertions, not only rendered the most boggy and unfruitful soils firm and stable, but in many instances, so mush improved their fertility, as to be productive of the finest grain.
Lands to be drained are usually divided into two classes: 1. Uplands, or those which are situated so high, that the water can descend from them, if properly collected and conducted; and, 2. Fens, marshes, or those lands which lie so low as to command no fall; have no descent; and some being even below the level of the sea.
I. With regard to uplands, it generally happens, that the waters from the springs beneath the soil are obstructed in their course to the neighbouring rivers. These springs originate from the atmospheric moisture; which, being condensed on the summits of hills into water, by the greater coldness of those parts, perforates the different strata of the incumbent soil, where it is of a porous nature; the water continues to descend, sometimes for many miles together, but generally from the nearest eminences into the adjoining valley, till its course is intercepted by a stratum of clay; where, being collected in considerable quantities, it is forced to work itself a passage through the porous strata of sand, gravel, or rock, that may be above the clay, following the course of these strata, till they approach the surface of the earth, or are interrupted by any obstacle, which causes the water to rise to the surface, and to form springs, bogs, marshes, &c.
At the foot of hills, therefore, where the plain begins to be too moist, some augur-holes should be bored, in order to find the depth of the springs, and consequently the thickness of the upper stratum of the soil. If this be only 4 or 6 feet, an horizontal ditch should be cut along the bottom of the hill, to intercept the water, which ought to be carried off by one or more ditches communicating with the former, and conducting the water thus collected, into the neighbouring rivulet. Farther, as the strata, through which the water descends in forming these springs, have, with a few exceptions, the same inclination as the surface of the hill, the holes should be bored, and the ditch cut, not vertically downwards, as is commonly practised, but perpendicularly to that surface; a method which greatly facilitates the arriving at the second stratum: this will be more evident from the subjoined cut.
a, b, is the upper stratum, for instance, of marl; c, d, is the second stratum, of sand; e, f, represents the accumulated earth in the valley. It is designed to shew, that, in boring holes through the upper stratum, in order to find that beneath it, they should be formed perpendicularly to the side of the mountain, and not perpendicularly to the horizon, as by the former method the hole y, y, is rendered much shorter than that marked x, x.
If, nevertheless, on cutting a ditch five or six feet deep, along the foot of a hill, vertically to the rising plain, the upper stratum be not penetrated, and consequently no water ooze in to the bottom of the ditch, it will be expedient to bore other holes at the bed of such ditch, some yards deeper, or till water ascend through them. Where this succeeds, many holes should be made, and the water, conducted into the adjacent brook, or river; for it will then rise, collect in those trenches six feet below the wet surface of the valley, and thus be carried off, instead of rising up from the lower wall-springs, or apertures of the stratum, through the incumbent soil, to the surface of the valley, which is so many feet higher.
This is the method which has been successfully practised, for several years, by Mr. Elkington; but the prior, or at least coeval, discovery of which, is justly claimed by Dr. James Anderson, who states (in the introduction to his ingenious "Essays on Agriculture," vol. iii.) that he sunk a hole with a wimble into the earth at the bottom of a ditch, in the year 1764; that the water rose six feet above the surface of the ground, and has continued flowing ever since, tho' with less rapidity.
These ditches should be made narrower as they descend, by spades of a proportionate sise and breadth: but the lowest part ought to be contracted more than any other, so that the shoulders or edges of it may support stones or faggots, in order to cover the whole, at a small expence, without obstructing the currents of water. In many places, hollow-bricks, ridge-tiles, or old fragments of plastered floors, may be applied to the same purpose; as they may be substituted for stones, or faggots, and at a reduced expence.
Situations, however, frequently occur, where the first stratum of the earth may be too thick to be easily perforated; or where the water, condensed from the atmosphere on the summits of the hills, may work itself a passage between the second and third, or between the third and fourth strata, which form the sides of those hills, from a deficiency of so many of the strata at their summits. Hence the water lies too deep to be retarded in its progress by a ditch, or by boring; but, being dammed up by the materials that form the plain of the valley, it ascends through them to the surface, and thus forms boggy, or marshy ground. In such cases, the common mode of draining may be successfully employed: it consists in cutting several ditches four or six feet across the bog, or morass; and in covering them so that the water may not be obstructed in its passage, but be thus in part collected and conveyed away, though certainly with less advantage than where springs can be intercepted.
Another method of draining is, that of opening thenches, or drains, almost annually, by a large plough with two converging coulters, and other appropriate machinery, for the purpose of cutting both sides of a ditch at the same time, and turning out the intervening soil.—These large ploughs are still kept in some parishes, and drawn over moist commons, by twelve or twenty horses, so as to form parallel ditches.
An instrument was invented for this purpose by Mr. Adam Scott, of Guildford, Surrey, called by him, a mole-plough, and for which the Society for the Encouragement of Arts, &c. in 1797, gave him a bounty of thirty guineas. It consists of a coulter, 15 inches in length, and 212 in width, to cut the sward. Behind this is applied an horizontal cone of cast iron, 20 inches long, and 212 in diameter at the base, to the middle of which is fixed an upright bar 2 feet long, and 312 inches broad, with a sharp edge. If this cone be drawn along moist lands, 6 or 8 inches beneath the turf, either in the spring or in autumn, in several parallel directions, the water will be conveyed away for a considerable space of time, without breaking the surface. With Mr. Scott's mole-plough, a man and boy with four horses may, with ease, drain thirty acres in a day; but, at the lower side of the ground intended to be drained, there should be made an open gripe or ditch, in order to receive the water from those small cavities which are formed by the plough, at the depth of 12 or 14 inches. In very moist lands, or in very wet seasons, if a larger number than six or eight horses be employed, their feet will not sink so deeply into the turf as each animal will draw less; should, however, the ground be so exceedingly sort as scarcely to support the cattle, that inconvenience may be obviated by fixing to the horse's feet broad wooden shoes, similar to the snow shoes made use of by the inhabitants of northern climates.—The price of this useful plough, when complete, does not exceed two guineas and a half.
In October, 1797, a patent was granted to Mr. Harry Watts, of Binley, Warwick, for his invention of an implement, or machine, for draining land, which appears to be an improvement on Mr. Scott's mole-plough. The only material difference which subsists between them, is Mr. Watts's application of a rolling cutter made of cast steel, or cast iron, in the beam of his implement, instead of the common coulter, which, in Mr. Scott's plough, is fastened in the usual manner, by wedges. The patentee has likewise added three cutters, which may occasionally be substituted for the rolling cutter or coulter above-mentioned. This implement requires from four to eight horses, which number may be increased, or diminished, according to the nature of the land, and the depth it is intended to be worked. But, before it is used, Mr. Watts observes, that the land to be drained should be carefully examined, in order to ascertain the most convenient place for carrying off the water: hence the lowest end or side of the field must be selected for that purpose. The price of Mr. Watts's machine, we understand, is not less than ten guineas.
The last method of draining uplands, of which we shall give an account, is that practised in the county of Berks. It consists in digging a trench 2 feet deep, one foot wide at the top, and 9 inches at the bottom, with a steep descent to a ditch, extending along the bottom of the grounds, and made of a proper width and depth, to receive and carry off the water. Within these trenches is formed a channel, the sides of which are composed of hard white chalk, cut nearly into the size of bricks; the whole is covered with pieces of the same material, and the crevices filled up with the chippings. The mouth of the channel, where the water falls into the ditch, is constructed with brick or flint, as chalk will not bear the frost, to which this part of the work must necessarily be exposed. On the top of the channel is placed a thin coat of wheat-straw, brambles, or any small brush-wood. The passage for the water will be somewhat more than 3 inches. In digging trenches of this kind, the workmen lay the best earth on one side by itself, in order to replace it on the surface, when the trenches are again filled up. But, in all cases, where land lies on a declivity, care should be taken, that the drains have an easy and gentle descent; for, if they have too rapid a fall, they are apt to burst, or excavate; and, their protection below being lost, the least pressure from above will consequently destroy the work.
II. With respect to the draining of those plains or morasses, where no fall can be procured, the water may, in many situations, be collected by cutting a long horizontal ditch above the level of the morass, so as to intercept all the wall-springs; and may then be carried off in wooden troughs, or hollow bricks, above die surface; and, if any water continue to penetrate the morass, it may be conducted to the extremity of the ground, either in open drains, or in covered brick drains, of which we have annexed the following cuts:
This figure represents a hollow brick, two of which, being placed one upon the other, form the pipe, which is chiefly useful tor making small drains.
D, D, are two bricks placed opposite each other, and then covered with E, a stone on the top, in which situation they will form a large drain.—The mould pressing on the sides of the bricks, keeps them firm and steady: the turf taken off the soil, ought to be laid upon the stone, with the grass side downwards.
The draining of low moist lands may also be advantageously effected by a roller or wheel. This is made of cast-iron, weighs 4cwt. and is 4 feet in diameter: The cutting edge, or extreme circumference of the wheel, is half an inch thick, which, increasing in thickness towards the nave or centre, will cut a drain half an inch in width at the bottom, 4 inches wide at the top, and about 15 inches deep. This wheel is so placed in a frame, that it may be loaded at pleasure, in order to score out a greater or less depth, according to the resistance of the ground; which being thus cut during the winter, the wheel-tracks are either then filled with straw ropes, and lightly covered over, or left to crack wider and deeper, during the succeeding summer; when the fissures should be kept open with twisted straw and bushes, and lightly covered with such porous soil as can be most conveniently procured. Thus hollow drains may be formed upon grass or ley-land, at little expence, and will answer every useful purpose.
The necessity and utility of draining the surface-water from clay soils, in wet seasons, is generally acknowledged; but, excellent as the different methods are in the cases before mentioned, they do not appear to be so simple, or so effectual, as could be wished in the present. Covered drains frequently fail in producing the desired effect, in consequence of the covering materials being of too close a texture to admit the water to filtrate through them with sufficient freedom. Mole-ploughs, of the best construction, require such a number of horses to draw them, as must necessarily injure the soil, by poaching it. Farther, covered drains are not only dangerous to full-grown sheep and young lambs, but from the quantity of clay necessarily dug up, and spread over the richer surface-soil, they are also injurious to vegetation. None of the several modes of draining now in use, being subservient to the essential purpose of conducting large quantities of water from a deep soil, we feel satisfaction in communicating the following simple contrivance of Mr. John Middleton, just published in the 22d No. of the "Commercial and Agricultural Magazine." It consists merely in adding a piece of wood to the felly of a common six-inch cart-wheel, to which is prefixed a rim of iron, of a triangular form. The whole expence of this addition does not exceed one guinea. A wheel of this description, when put on the axle of a cart in the usual way, will of course rest on the edge of the triangular rim of iron abdve alluded to; and, on driving the horses forward, will make a small indent in the ground, merely by its own revolution. But, in order to press it down to the depth of six or eight inches, that side of the cart should be laden with stones, iron, or any other heavy material, until the whole of the rim, as well as the additional piece of wood, and the felly itself, if necessary, sink into the soil. The cart should then he drawn in such a direction that the cutting-wheel may revolve where the drains are intended to be formed. Sometimes it will be necessary to apply the indenting machine to every furrow; but, where the land is level, it should be drawn over it in parallel lines, five or ten yards apart. The wheel on the opposite end of the axle is a common six-inch wheel, which supports only the empty side of the cart, and consequently will not cut the ground.
The advantage of this contrivance, as stated by Mr. Middleton, is, that it makes an indent in the soil sufficient to carry off the water during the ensuing winter, by pressing down the herbage, without destroying it. In the succeeding spring, these drains will be nearly grown up, so that there is no injury done to the grass. He observes, however, that this wheel should be drawn over the ground every year, on the approach of winter; but so easy is its application, that by menus of it, and two old horses, one stout boy, or man, may drain from ten to twenty acres in eight hours.
The first oject in draining a bog or marsh, is, to discover the lowest spot of dry ground that surrounds it, in order to open on that part the main trench which is to carry off the water: if there be the least appearance of any stream, it should be traced with care; for this will point out the proper spot on which to begin. The main trench, commencing at the lowest part, may be carried to whatever distance it is thought proper: if it begin at the right spot, 10 acres may be detached from the marsh, however extensive, and completely drained; but, if the drainage be not begun where there is a sufficient fall, the labour bestowed will be to no purpose: the main cut or trench should be 10 feet broad in the clear, with a proper slope, to prevent the sides from falling in, and filling it up.
Bogs are divided into two sorts, black and red.—The former are solid, and make excellent fuel for common fires, or for burning lime; but the red bog consists of a loose, porous, fungous mass, which burns badly, and yields no ashes. Hence, in black bogs only, the drains ought to be cut into turfs, dried, carted, and piled.
As the main canal advances, small ones may be conducted into it on either side, inclosing such spots of gronnd as are intended to be improved. No certain rule can be laid down for the depth of drains; yet we apprehend the prevailing practice of cutting them down to the solid ground beneath the bog, is founded on the erroneous principle, that such depth is sufficient as will leave the surface dry. Numerous drains, however, being always useful and necessary, the spots inclosed ought not to contain more than five acres; but in such space it is requisite that several cross-cuts be made, which should be 4 feet broad at the top, and 3 feet deep. A whole year will be requisite to complete these drains; and, in the ensuing spring, it will be necessary to open, deepen, and clear them of the adventitious boggy matter; a work which should be occasionally renewed. The second year may be employed in extending the main trench; in taking in fresh inclosures by new lateral cuts; and in draining these by means of small transverse drains. Although this annual deepening and clearing of marshy grounds be attended with great labour and expence, yet the operation is thus progressively completed, and in succeeding years both trouble and costs will be gradually diminished, in proportion as the bog subsides.
As soon as the drains have rendered the marshes sufficiently firm for oxen to walk on them, the heaviest rollers that can be procured should be employed, to act by repeated pressure. Indeed, without a considerable degree of such pressure, during the first year, no bog can be effectually consolidated. An alternate draining and rolling, annually (the drains being still kept open), would, probably, contribute much to the destruction of weeds. Previous to rolling in the spring, it has been strongly recommended to sow every kind of grass-seeds, indiscriminately, such as ray-grass, hay-seed, clover, &c.
An instance of uncommon and successful industry occurs in the 18th vol. of the "Transactions of the Society for the Encouragement of Arts," &c. which in the year 1800 conferred a gold medal on John Morehouse, Esq. of Brownslade, in the county of Pembroke, for improving 274 acres of waste moor-lands, which were formerly a common, and so completely inundated as to be of no value whatever.
Before we conclude this subject, we think it necessary to give some account of stone drains, which are calculated for soils where the common methods of draining cannot be adopted. Such drains ought to be cut 10 or 12 inches wide, with perpendicular sides; and flat stones should be so placed, as to leave a water-course at the bottom, by setting two stones triangularly to meet at the points. Or, the bottom may be covered with a flat stone, and three others placed upright, and the water left to work itself a passage between them. In either case, the cavity of the drain ought to be filled nearly up to the top with loose stones: screened or washed gravel, where it is found in greater abundance, has been successfully substituted. Those pebbles, however, which are often found on the sea-shores, are well adapted for filling drains; as, being smooth, and generally round, the water flows through them more freely.
The principal drains ought to be 3 feet deep, and 18 inches in width; the bottom and top should be laid with flag-stones; the sides built up to a sufficient height with common stones; and the whole covered with sods of turf, but the grassy sides downwards: these again are to be overspread with earth, sufficient to admit the plough. The smaller drains are, in general, to be concluded at an acute angle into the main trenches.
Lastly, sod or earth-drains are usually dug two feet deep with a spade, when the soil is taken out by an instrument, or scoop, about four inches wide, and the drain covered with the sods first dug out, if the ground be firm enough to support them; or, some black-thorns are put in, in order to bear the weight of the sods. Those drains which have the smallest passage for the water at the bottom, are reputed to be the most durable; as the force of the water has been found sufficient to clear away any small obstacles accidentally obstructing its course.
Hollow drains, without stones, have been tried on stiff lands: they are made narrow at the bottom, and covered half way up with sods, or square pieces of the surface-sward, resting on ledges cut for that purpose.
It is much to be lamented, that we possess, in this cold climate, no grain similar to rice, that would grow in watery grounds which cannot be drained, nor indeed any esculent roots or foliage, except water-cresses. In such situations, some plants may perhaps be cultivated with profit to the proprietor, as the Festuca fluitans, or Floating Fescue; Callitriche, or Star-grass, or Star-wort; to which may be added the Orchis, for the purpose of making salep, by drying the peeled roots in an oven. If these plants should not completely succeed, other vegetables of quick growth may be raised for manures, such as the Typha, or Cat's-tail; the Caltha, or Marsh-marigold, &c.; which should be mown twice a year, while they are young, and abound with saccharine and mucilaginous matter, ready to pass into fermentation.
It frequently happens that, notwithstanding all the labour and expence which the industrious cultivator may bestow on the construction of drains, his lands become, in the course of time, soft and wet, so that they gradually return to their former state. This unfavourable change is often occasioned by the Eqiusetum palustre, or Marsh Horse-tail, a plant growing on swampy ground, which has been found vegetation within the drains, to a very considerable extent, and thus, at first intercepting or obstructing the course of the water, then gradually weakening the current, and at length wholly choaking up the drain. The only remedy yet known is, in the opinion of Sir Joseph Banks, to cast the under drains into open ones, as soon as this evil can be ascertained.
Those who wish to acquire more minute information on this subject, we must refer to Dr. Anderson's excellent "Practical Treatise on draining Bogs and swampy grounds," (8vo. pp. 308, 6s. boards. Robinsons, 1797): and to Mr. Johnstone's "Account of the most approved Mode of Draining Land," &c. (4to. 1l. 5s.) in which it is amply investigated.—See also Ponds, with a Plate.