small weight without breaking, although it yields very much, it is in these circumstances called a swaggle. But, whatever be the nature of the bog, it is invariably occasioned by water being forced up through a bed of clay, as just now described, and dissolving or softening, if you will, a part thereof: I say only a part; because whatever may be the depth of the bog or swaggle, it generally has a partition of solid clay between it and the reservoir of water under it, from whence it originally proceeds: for if this were not the case, and the quantity of water were considerable, it would meet with no sufficient resistance from the bog, and would issue through it with violence, and carry the whole semi-fluid mass along with it. But this would more inevitably be the case if there was a crust at the bottom of the bog, and if that crust should ever be broken, especially if the quantity of water under it were very considerable and as it is probable, that in many cases of this sort, the water slowly dissolves more and more of this under crust, I make no doubt, but that in the revolution of many ages a great many eruptions of this kind may have happened, though not deemed of sufficient importance to have the history of them transmitted to posterity. Of this kind, although formed of a different substance, I consider the flow of the Solway moss, in Northumberland, to have been; which, upon the 16th of November, 1771, burst its former boundaries, and poured forth a prodigious stream of semi-fluid matter, which in a short time covered several hundred acres of very fine arable ground. Nor will any one, who is acquainted with the nature of moss, who knows its resemblance to clay, in its quality of absorbing and retaining water, and its very easy diffusibility therein, be surprised at this; as, from all these properties, it is much better adapted for forming an extensive bog, and therefore in greater danger of producing an extensive devastation by an eruption of the water into it, than those that are formed of any kind of clay whatever. If the bog or swampy ground is upon a declivity, the ditch ought to be carried across the field about the place where the lowest springs arise. But if the surface of the ground is level, or nearly so, as between A and B, fig. 4, and the springs break out in several places, 99999, so as to form soft quagmires, interspersed through the whole of the field, it will be of little consequence in what part the drain is opened; for if it be dug up so deep as to allow the water to rise in it with freedom, it will issue through that opening, and the field will be left perfectly dry. But as it may frequently happen that the stratum of gravel should be at a considerable depth beneath the surface of the earth, and as it may be sometimes even below the level of the place into which the drain must be emptied, it might sometimes be extremely difficult to make a ditch so deep as to reach the bed of sand or gravel. But it is lucky for us that this is not absolutely necessary in the present case; as a drain of two or three feet deep, as at D, will be equally effectual with one that should go to the gravel. All that is necessary in this case, is to sink pits P in the course of the drain, at a moderate distance from

one another, which go so deep as to reach the gravel; for, as the water there meets with no resistance, it readily flows out at these openings, and is carried off by the drain without being forced up through the earth; so that the ground is left entirely dry ever after. I have likewise drained several fields in this way; and, as I have generally found the appearance pretty much alike, I shall, for the information of the inexperienced reader, give a short account of them. If you attempt to make your pit in one of these soft quaggy places where the water is found in great abundance, you will meet with very great difficulty in forming it; for, as the substance of which it is composed is soft, it will always flow into the hole as fast as you dig it; on which account I would advise, not to attempt to make the pit in the swaggle, but as near it in the solid earth as you conveniently can. However, if it is pretty firm, and of no great extent, it is sometimes practicable to make a pit in the soft bog at the driest time of the year. This I have sometimes practised, which gave me an opportunity of observing the nature of these bogs more perfectly than I otherwise should have had. In the trials of this kind that I have made, this soft quaggy ground has seldom been above three or four feet deep, below which I have always found a stratum of hard tough clay usually mixed with stone; and so firm, that nothing but a mattock or pick-axe could penetrate it; and, as this is comparatively so much drier than the ground above it, an inexperienced operator is very apt to imagine that this is the bottom that he is in search of. In digging through this stratum you will frequently meet with small springs oozing out in all directions; some of them that might fill the tube of a small quill, and others so small as to be scarcely perceptible; but, without regarding these, you must continue to dig on, without intermission, till you come to the main body of the reservoir, if I may so call it, that is contained in the rock, gravel, or sand; which you will generally find from two to four feet below the bottom of the swaggle, and which you will be in no danger of mistaking when you come to it: for, if there has been no opening made before that in the field, as soon as you break the crust immediately above the gravel or rock, the water bursts forth like a torrent; and, on some occasions, rises like a jet d'eau to a considerable height above the bottom of the ditch; and continues to flow off with great impetuosity for some time, till the pent up water being drained off, the violent boiling up begins to subside, and the strength of the current to abate; and, in a short time, it flows gently out like any ordinary spring;

allowing it to remain in this state, the quaggy earth begins to subside, and gradually becomes firmer and firmer every day; so that, in the space of a few months, those bogs which were formerly so soft as hardly to support the weight of a small dog, become so firm, that oxen and horses may tread upon them without any danger of sinking, at the very wettest season of the year. I have had a field of this nature, that, by having only one such pit as I have now described opened in it, was entirely drained to the distance of above 100 yards around it in every direction. But as it is possible that the stratum in which the water

runs may be in some places interrupted, it will de in general expedient to make several of these its, if the field is of great extent; always carying the drain forward through the lowermost part of the field, or as near the quag as you conveniently can; and sinking a pit wherever you may judge it will be most necessary. But, if the stratum of gravel is not interrupted, there will be no violent burst of water at opening any of these after the first, as I have frequently experienced. To keep these wells from closing up after they are made, it is always expedient to fill them up with small stones immediately after they are made, which ought to rise to the height of the bottom of the drain. I have often imagined, that the expense of digging these pits might be saved by boring a hole through this solid stratum of clay with a large wimble made on purpose; but, as I never experienced this, I cannot say whether or not it would answer the desired end exactly. If the whole field that is to be drained consists of one extensive bog, it will require a long time before the whole work can be entirely finished, as it will be impossible to open a drain through it till one part of it is first drained, and becomes solid ground. In a situation of this kind, the undertaker, after having opened a drain to convey the water from the lowest part of the bog, must approach as near to the swampy ground as he can, and there make his first pit; which will drain off the water from the nearest parts of the bog. When this has continued open for some time, and that part of the bog has become so solid as to admit of being worked, let him continue the ditch as far forward through it as the situation it is in will admit of, and there sink another pit, and proceed gradually forward in the same manner; making cross cuts where necessary, till the whole be finished. In this manner, may any bog or track of spouting ground of this nature, be rendered dry at a very inconsiderable expense; and, as there can be no other method of draining ground of this sort effectually, I recommend the study of it to the attention of every diligent farmer who may have occasion for it. Let him first be extremely cautious in examining all the circumstances of his particular fields, that he may be certain which of the classes above enumerated it may be ranked with; and, when he is perfectly sure of that, he may proceed without fear, being morally certain of success. There is, however, one kind of damp ground not yet particularly specified, that I have purposely omitted taking notice of till this time, as I have never had any opportunity of examining particularly into the nature of it, nor of ascertaining, by experience, what is the most proper method of treating it. The soil I have now particularly in my eye, consists of a deep strong clay that does not vary its nature even on the surface, but in as far as manures may have rendered it more friable and tender; the color usually inclines to a reddish cast, and, for the most part, it is situated upon the side of some declivity. This bed of clay reaches to a great depth, without any variation, and is intermixed with a considerable quantity of small round stones. Many soils, of the sort now described, are apt to be continually moist and full of water during the winter season;

but when the dry weather of summer sets in, the moisture is diminished, and the surface becomes hard; and it is rent into many large gaps which allow free admission to the sun and air, so as to scorch up almost every plant that is sowed upon it; and, as these soils are usually in themselves naturally fertile when drained, it were to be wished that some method could be discovered, that would be less expensive than what is usually practised with regard to some soils of this kind in Essex; where they make covered drains of two feet and a half deep, running diagonally through the whole field, at the distance of twenty feet from each other.'

In the Georgical Essays, T. B. Bayley, Esq. of Hope, near Manchester, gives the following directions for making covered drains:- First make the main drains down the slope or fall of the field. When the land is very wet, or has not much fall, there should, in general, be two of these to a statute acre; for the shorter the narrow drains are, the less liable they will be to accidents. The width of the trench for the main drains should be thirty inches at top, but the width at the bottom must be regulated by the nature and size of the materials intended to be used. If the drain is to be made of bricks ten inches long, three inches thick, and four inches in breadth, then the bottom of the drain must be twelve inches; but if the common sale bricks are used, then the bottom must be proportionably contracted. In both cases there must be an interstice of one inch between the bottom brick and the sides of the trench, and the vacuity must be filled up with straw, rushes, or loose mould. For the purpose of making these drains, I order my bricks to be moulded ten inches long, four broad, and three thick, which dimensions always make the best drains. The method I pursue in constructing my main drains is as follows: when the ground is soft and spongy, the bottom of the drain is laid with bricks placed across. On these, on each side, two bricks are laid flat, one upon the other, forming a drain six inches high and four broad, which is covered with bricks laid flat. When the bottom of the trench is found to be a firm and solid body, as clay, or marle, the bottom of the drain does not then require being laid with bricks. In that case, the sides are formed by placing one brick edgeways, instead of two laid flat. This latter method is much cheaper, and in such land equally durable with the other. When stones are used instead of bricks, the bottom of the drain should be about eight inches in width. And here it will be proper to remark, that, in all cases, the bottom of the main drains must be sunk four inches below the level of the narrow ones, even at the point where the latter fall into them. The main drains should be kept open till the narrow ones are begun from them, after which they may be finished; but before the earth is returned upon the stones or bricks, it will be advisable to throw in straw, rushes, or brush-wood, to increase the freedom of the drain. The small narrow drains should be cut at the distance of sixteen or eighteen feet from each other, and should fall into the main drain at very acute angles, to prevent any stoppage. At the point where they fall

in, and eight or ten inches above it, they should be made firm with brick or stone. These drains should be eighteen inches wide at top, and sixteen at bottom.' See plate Dogs and DRAINS. Fig. 3, represents a field with drains, laid out according to Mr. Bayley's method. The black lines represent the main drains, and the dotted lines represent the narrow drains communicating with the former from all parts of the field.

About the same time that Dr. Anderson had reduced the system of draining to scientific principles in Scotland, Mr. Joseph Elkington, of Princethorpe, in Warwickshire, appears to have made some similar discoveries in England. The priority, indeed, is claimed by Dr. Anderson, but as each party has his merits, and as the public is, doubtless, highly indebted to both, we shall not presume to decide upon this point. The great object of Mr. Elkington's system is the draining of lands rendered wet by waters confined beneath the surface, and attempting to rise in the manner of springs. Among these, bogs or morasses are the chief. Having attempted, a considerable number of years ago, to drain a piece of ground of this kind on his farm at Princethorpe, by making a trench of five feet deep, but without success, he thought it might be of use to know, what kind of strata lay under the trench. Accordingly, he forced an iron crow, of about an inch and a half in diameter, three feet down, and upon taking it out, was agreeably surprised, to find a great quantity of water burst forth, and run down the trench. This led him to think of applying an auger, an instrument fitter for the purpose of boring, which, upon trial, he found equalled his expectations; and, by continuing the same plan with the auger, he at last drained all the wet parts of his farm, which were numerous, and had proved destructive to his sheep, by inducing the rot. When a morass is to be drained, his first object is to ascertain the direction in which the trench is to be dug. The substance of his rules for this, as laid before the Board of Agriculture in 1796, are these: 1. To obtain as much knowledge as possible respecting the strata in the neighbourhood. 2. To direct the trench so as to hit the bottom of the bed, which occasions the mischief, and the particular spot where the main spring lies. 3. If there are various beds through which the water issues, to prefer the stone one for draining the whole; and to make the trench from six to eight yards from the tail of the bed, where the rock ends, because in limestone, and other rocks, the tail, as it is technically termed, is harder than any other part of the rock; but a few yards above it, it is softer, and the water is more accessible. The tail of these beds may often be found jutting out in a point. 4. To direct the trench in a line with the bottom of the hill; as it makes the best separation between the upland and meadow enclosures, where the spring can be best intercepted. The trench, however, must be carried in or near the line of the spring; for, if it diverges to any distance, all chance of reaching the spring by tapping is over, and the labor of digging it probably lost. 5. To make a new trench, rather than to to tap the spring in any old brook, or run of water. 6, and lastly, having fixed on the line

of direction, and marked out the trench, to begin at the bottom or lowest level, carrying the trench gradually up. The fall of the water need not be above a few inches in 100 yards. The auger, which must often be used for tapping, need not exceed two inches in diameter. Mr. Elkington bored a hole with one, to the depth of thirty feet, which threw up water equal to three hogsheads in a minute, and completely drained all the neighbourhood. In such cases, farther operations in draining are unnecessary. In other cases, the trench being once made, and the spring cut off, by tapping, or otherwise, it remains only to determine, whether it is to be kept open or covered. If the drain can be made a fence, he prefers leaving it open; if not, to cover it. His mode is, to make it square, either of brick or flat stones. A trench made of a particular kind of bricks, invented by Mr. Elkington, may last for fifty, or even 100 years. Mr. Elkington proposes a farther improvement of this discovery, by applying the treasures of water thus obtained to the purpose of flooding dry grounds, as well as to the turning of mills, and to other engines used in manufactures.

6

On the drainage of mixed and varied soils of the clayey kind, we have the following useful observations in Mr. Loudon's Encyclopedia of Agriculture :-The business of draining is here,' he remarks, considerably more tedious and difficult than where the superficial and internal parts have greater regularity. In such sorts of lands, as all the different collections of water are perfectly distinct from each other, by means o. the beds of clay that separate them, each collection becomes so much increased, or accumulated, in the time of heavy rains, that they are filled quite to the level of the surface of the clay by which they are surrounded; when the water getting a free passage, as it would over the edges of a bowl or dish, overflows and saturates the surface of that bed of clay in such a manner, as to render it so perfectly wet and sour, that its produce becomes not only annually more and more scanty, but the soil itself more sterile and unproductive. From the sand-beds, in such cases, having no communication with each other, it must evidently require as many drains as there are beds of this kind, in order fully to draw off the water from each of them. A drain or trench is therefore recommended to be cut from the nearest and lowest part of the field intended to be drained, up to the highest and most distant sand-bank in such a line of direction as, if possible, to pass through some of the intermediate sand-beds, and prevent the labor and expense of making longer cuts on the sides, which would otherwise be requisite.

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 that is contained in the sand, and which, being constantly full, renders the adjacent clay moist; and in wet seasons runs or trickles over

it. As, in these cases, the principal under-stratum of clay is rarely above four or five feet below the surface, a drain is advised to be cut 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 in that place, as the water will more readily discharge itself into it; and unless the field be of great extent, and have more depressions or hollows in it than one, 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 of them. A principal difficulty in draining ground of this nature, and which renders it impracticable by one drain, is when the direction of the alternate layers, or beds of clay and sand, lie across the declivity of the land, 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 was 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, to have others cut up from it in a slanting direction across the declivity, which by crossing all the different veins, or narrow strata of sand, may be capable of drawing the water from each of them. 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 by small stones, tough sods being applied, the green side downwards, upon them before the mould is filled in. But, where stones cannot be readily procured, faggots may be employed in their place, where they are plentiful: the under part of the drain being laid, or coupled, with stones, so as to form a chaunel or passage 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.

'The mode of draining retentive soils, is materially different from that which has been described above. Many tracts of level land are injured by the stagnation of a superabundant quantity of water in the upper parts of the surface materials, which does not rise up into them from any reservoirs or springs below. The removal of the wetness in these cases may, for the most part, be effected without any very heavy expense. From the upper or surface soil, in such cases, being constituted of a loose porous stratum of materials, to the depth of from two to four or five feet, which has a stiff retentive body of clay underneath it, any water that may come upon the surface from heavy rains, or other causes, readily filtrates and sinks down through it, until it reaches the obstructing body of clay which prevents it from proceeding; the consequence of which is, that the porous open soil above is so filled and saturated with water, as to be of little utility for the purpose of producing crops of either grain or grass. Land situated in this way, is frequently said by farmers to be wet

bottomed. In order to remove this kind of wetness, it seldom requires more than a few drains, made according to the situation and extent of the field, of such a depth as to pass a few inches into the clay, between which, and the under surface of the porous earth above, there will obviously be the greatest stagnation, and consequently, collection of water, especially where it does not become much visible on the surface. In these cases there is not any necessity for having recourse to the use of the boring instrument, as there is no water to be discharged from below. When the field to be drained has only a slight declination, or slope, from the sides towards the middle, one drain cut through the porous superficial materials into the clay, in the lowest part of the ground, may be sufficient to bring off the whole of the water detained in the porous soil. This effect may likewise be greatly promoted, by laying out and forming the ridges so as to accord with the direction of the land, and by the use of the plough or spade in removing obstructions, and deepening the furrows. In such situa tions, where the drain has been formed in this manner, the water will flow into it through the porous surface materials, as well as if a number of small trenches were cut from it to each side, as is the practice in Essex and some other parts of the country; but which is often an unnecessary labor and expense. The drain made in the hollow may frequently serve as a division of the field, in which case it may be open; but in other circumstances it may be more proper to have it covered. Where a field of this description has more than one hollow in its surface, it will obviously be requisite to have more than one main drain; but when it is nearly level, or only inclines slightly to one side, a trench or drain along the lowest part, and the ridges and furrows formed accordingly, may be sufficient for effecting its drainage. There may, however, be cases, as where a field is large and very flat, in which some side-cuts from the principal drain may be necessary, which must be made a little into the clay, and as narrow as they can be wrought, and then filled up with stones or other suitable materials.'

What is called the Essex method of draining in ploughed springy lands, where the surface soil is tenacious, is described by Kent, and consists in substituting small under-drains for open furrows; or in some cases having a small underdrain beneath every other or every third furrow, These drains lead to side or fence ditches, where they discharge themselves.' For draining of mines, see MINING.

Drains may be conveniently classed, as Mr. Loudon observes, under, 1. Drains of conveyance simply; and 2. Drains of conveyance and collection. The most complete drain of conveyance is a large pipe of metal, masonry, or brickwork: and the most complete collecting drain, one formed with a channel built on the sides, and covered with flat-stones, with a superstratum of round stones or splinters, diminishing to the size of gravel as they rise to the surface, and there covered with the common soil. As the best constructions, however, are not always practicable, the following are a few leading sorts