BOOK III.

OF IMPROVING THE CULTURABLE LANDS OF AN ESTATE.

3908. HAVING completed the general arrangement of an estate, the next thing is to improve the condition of that part of it destined to be let out to tenants, and from which, as already observed, the chief source of income is derived. The farm lands being enclosed and subdivided, and the farmeries and cottages built in their proper situations, in many cases no other improvements are wanted on the soil than such as are given by the tenant in the ordinary course of culture. But there are also numerous cases, in which improvements are required which could not be expected from an occupier having only a temporary interest in his possession; and these form the present subject of discussion. Such improvements are designated by agriculturists permanent, as conferring an increased purchasable value on the property, in opposition to improvements by a temporary occupier, the benefits of which are intended to be reaped during his lease. The latter class of improvements include fallows, liming, marling, manuring, improved rotations, and others of greater expense, according to the length of lease, rent, and encouragement given by the landlord; the former, and which we are now about to discuss, include draining, embanking, irrigating, bringing waste lands into cultivation, and improving the condition of lands already in a state of culture.

CHAP. I.

Of Draining Watery Lands.

3909. Draining is one of those means of improvement, respecting the utility of which agriculturists are unanimous in opinion. Though practised by the Romans (143.), and in all probability in some cases by the religious fraternities of the dark ages, it was not till after the middle of the last century that its importance began to be fully understood in Britain; and that some individuals, and chiefly Dr. Anderson and Elkington, began to practise it on new principles. About the same time, the study of geology became more general, and this circumstance led to the establishment of the art on scientific principles. The public attention was first excited by the practice of Elkington, a farmer and selftaught professor of the art of draining in Warwickshire and the adjoining counties. On the practice of this artist most of the future improvements have been founded; and they have been ably embodied in the account of his practice by Johnston, from whose work we shall draw the principal materials of this section, borrowing also from the writings of Dr. Anderson, Marshal, Smith, Farey, and some others on the same subject. After submitting some general remarks on the natural causes of wetness in lands, we shall consider in succession the drainage of boggy lands, hilly lands, mixed soils, retentive soils, and mines and quarries; and then the kinds of drains, and draining materials. SECT. I. Of the Natural Causes of Wetness in Lands, and the general Theory of Draining. 3910. The successful practice of draining in a great measure depends on a proper knowledge of the structure of the earth's upper crust; that is, of the various strata of which it is composed, as well as of their relative degrees of porosity, or capability of admitting or rejecting the passage of water through them, and likewise the modes in which water is formed, and conducted from the high or hilly situations to the low or level grounds. whatever way the hills or elevations that present themselves on the surface of the globe were originally formed, it has been clearly shown, by sinking large pits, and digging into them, that they are mostly composed of materials lying in a stratified order, and in oblique or slanting directions downwards. Some of these strata, from their nature and properties, are capable of admitting water to percolate or pass through them; while others do not allow it any passage, but force it to run or filtrate along their surfaces without penetrating them in any degree, and in that way to conduct it to the more level grounds below. There it becomes obstructed or dammed up by meeting with impervious materials of some kind or other, by which it is readily forced up into the super-incumbent layers where they happen to be open and porous, soon rendering them too wet for the purposes of agriculture; but where they are of a more tenacious and impenetrable quality, they only become gradually softened by the stagnant water below them; by which the surface of the ground is, however, rendered equally moist and swampy, though somewhat more slowly than in the former case. It may also be observed, that some of the strata which constitute such hilly or mountainous tracts are found to be continued with much greater S s

In

regularity than others; those which are placed nearest to the surface at the inferior parts of such hills or elevations, being mostly broken or interrupted before they reach the tops or higher parts of them; while those which lie deeper, or below them at the bottom, show themselves in these elevated situations. Thus, that stratum which may lie the third or fourth, or still deeper, at the commencement of the valley may form the uppermost layer on the summits of hills or mountainous elevations. This arrangement or distribution of the different strata may have been produced partly by the circumstances attending the original elevation of such mountainous regions, and partly from the materials of the original exterior strata being dissolved and carried down into the valleys by successive rains and other causes, and thus leaving such as were immediately below them in an exposed and superficial state in these elevated situations. (Darwin's Phytologia, p.258.)

3911. These elevated strata frequently prove the means of rendering the grounds below wet and swampy; for, from the night dews, and the general moisture of the atmosphere, being condensed in much greater quantities in such elevated situations, the water thus formed, as well as that which falls in rain and sinks through the superficial porous materials, readily insinuate themselves, and thus pass along between the first and second, or still more inferior strata which compose the sides of such elevations; until their descent is retarded or totally obstructed by some impenetrable substance, such as clay; it there becomes dammed up, and ultimately forced to filtrate slowly over it, or to rise to some part of the surface, and constitute, according to the particular circumstances of the case, different watery appearances in the grounds below. These appearances are, oozing springs, bogs, swamps, or morasses, weeping rocks from the water slowly issuing in various places, or a large spring or rivulet from the union of small currents beneath the ground. This is obvious from the sudden disappearance of moisture on some parts of lands, while it stagnates, or remains till removed by the effects of evaporation on others; as well as from the force of springs being stronger in wet than dry weather, breaking out frequently after the land has been impregnated with much moisture in higher situations, and as the season becomes drier ceasing to flow, except at the lowest outlets. The force of springs, or proportion of water which they send forth, depends likewise, in a great measure, on the extent of the high ground on which the moisture is received and detained, furnishing extensive reservoirs or collections of water, by which they become more amply and regularly supplied. On this account, what are termed bog-springs, or such as rise in valleys and low grounds, are considerably stronger and more regular in their discharge, than such as burst forth on the more elevated situations or the sides of eminences. (Johnston's Account of Elkington's Mode of Draining Land, p. 15.)

3912. The waters condensed on elevated regions are sometimes found to descend, for a very considerable distance, among the porous substances between the different conducting layers of clayey or other materials, before they break out or show themselves in the grounds below; but it is more frequently the case to find them proceeding from the contiguous elevations into the low grounds that immediately surround them.

3913. The nature of the stratum of materials on which the water proceeding from hills has to penetrate, must considerably influence its course, as well as the effects which it may produce on such lands as lie below, and into which it must pass. Where it is of the

clayey, stiff marly, or impervious rocky kinds, and not interrupted or broken by any other kind of materials of a more porous quality, it may pass on to a much greater distance, than where the stratum has been frequently broken and filled up with loose porous materials, in which it will be detained, and of course rise up to the surface.

3914. These sorts of strata extend to very different depths in different situations and districts, as has been frequently noticed in the digging of pits, and the sinking of deep wells, and other subterraneous cavities. The clayey strata are, however, in general found to be more superficial than those of the compact, tenacious, marly kinds, or even those of a firm, uninterrupted, rocky nature, and seldom of such a great thickness; they have, nevertheless, been observed to vary greatly in this respect, being met with in some places of a considerable thickness, while in others they scarcely exceed a few inches.

3915. The intervening porous substances, or strata where clay prevails, are found, for the most part, to be of either a gravelly or loose rocky nature. Stiff marly strata, which approach much to the quality of clay, though in some instances they may present themselves near the surface, in general lie concealed at considerable depths under the true clayey strata, and other layers of earthy or other materials; they have been discovered of various thicknesses, from eight or ten feet to considerably more than a hundred. (Darwin's Phytologia, p. 259.) The intervening materials, where strata of this nature are predominant, are most commonly of the more sandy kinds; possessing various degrees of induration, so as in some cases to become perfectly hard and rocky, but with frequent breaks or fissures passing through them. The loose, friable, marly strata are capable of

absorbing water, and of admitting it to filtrate and pass through them. 3916. Thus the valleys and more level grounds must constantly be liable to be overcharged with moisture, and to become, in consequence, spouty, boggy, or of the nature of a morass,

accordingly as they may be circumstanced in respect to their situation, the nature of their soils, or the materials by which the water is obstructed and detained in or upon them. 3917. Where lands have a sufficient degree of elevation to admit of any over-proportion of moisture readily passing away, and where the soils of them are of such an uniform sandy or gravelly and uninterrupted texture, as to allow water to percolate and pass through them with facility, they can be little inconvenienced by water coming upon or into them, as it must of necessity be quickly conveyed away into the adjacent rivers or small runlets in their vicinity.

3918. But where grounds are in a great measure flat, and without such degrees of elevation as may be sufficient to permit those over-proportions of moisture that may have come upon them from the higher and more elevated grounds, to pass readily away and be carried off, and where the soils of the lands are composed or constituted of such materials as are liable to admit and retain the excesses of moisture; they must be exposed to much injury and inconvenience from the retention and stagnation of such quantities of water. Such lands consequently require artificial means to drain and render them capable of affording good crops, whether of grain or grass.

3919. Lands of valleys and other low places, as well as, in some cases, the level tracts on the sides or borders of large rivers and of the sea, must also frequently be subject to great injury and inconvenience from their imbibing and retaining the water that may be thus forced to flow up into or upon them, either through the different conducting strata from the hills and mountainous elevations in the neighborhood, or the porous materials of the soils. In these ways they may be rendered swampy, and have bogs or morasses produced in them in proportion to the predominancy of the materials by which the water is absorbed and dammed up, and the peculiarity of the situation of the lands in respect to the means of conveying it away.

3920. To perform properly the business of draining, attention should not only be paid to the discrimination of the differences in regard to the situation of the lands, or what is commonly denominated drainage level; but also to the nature, distribution, and depth of the materials that constitute the soils or more superficial parts of them, as upon each of these some variety, in respect to the effects arising from water retained in them, may depend.

3921. Wetness of land, so far as it respects agriculture, and is an object of draining, may generally depend on the two following causes: first, on the water which is formed and collected on or in the hills or higher grounds, filtrating and sliding down among some of the different beds of porous materials that lie immediately upon the impervious strata, forming springs below and flowing over the surface, or stagnating underneath it; and secondly, on rain or other water becoming stagnant on the surface, from the retentive nature of the soil or surface materials, and the particular nature of the situation of the ground. The particular wetness which shows itself in different situations, in the forms of bogs, swamps, and morasses, for the most part proceeds from the first of these causes; but that superficial wetness which takes place in the stiff, tenacious, clayey soils, with little inclination of surface, generally originates from the latter.

3922. The most certain and expeditious method of draining, in such cases, is that of intercepting the descent of the water or spring, and thereby totally removing the cause of wetness. This may be done where the depth of the superficial strata, and consequently of the spring, is not great; by making horizontal drains (fig. 483 a) of consi

derable length across the declivities of the hills, about where the low grounds of the valleys begin to form, and connecting these with others (6) made for the purpose of conveying the water thus collected into the brooks or runlets (c: that may be near. Where the spring has naturally formed itself an outlet, it may frequently only be necessary to bore into it (e) or render it larger, and of more depth; which, by affording the water a more free and open passage, may evacuate and bring it off more quickly, or sink it to a level so greatly below that of the surface of the soil, as to prevent it from flowing into or over it.

3923. Where the uppermost stratum is so extremely thick as not to be easily penetrated, or where the springs, formed by the water passing from the higher grounds, may be con. fined beneath the third or fourth strata of the materials that form the declivities of hills or elevated grounds, and by this means lie too deep to be penetrated to by the cutting of a ditch, or even by boring (Darwin's Phytologia, p. 263.); the common mode of cutting a great number of drains to the depth of five, six, or more feet, across the wet morassy grounds, and afterwards covering them in such a manner as that the water may suffer no interruption in passing away through them, may be practised with advantage, as much of the prejudicial excess of moisture may by this means be collected and carried away, though not so completely as by fully cutting off the spring.

3924. As water is sometimes found upon thin layers of clay, which have underneath them sand, stone, or other porous or fissured strata, to a considerable depth; by perforating these thin layers of clay in different places, the water which flows along them may frequently be let down into the open porous materials that lie below them, and the surface land be thus completely drained.

3925. Where morasses and other kinds of wetnesses are formed in such low places and hollows as are considerably below the beds of the neighboring rivers, they may, probably, in many instances, be effectually drained by arresting the water as it passes down into them from the higher grounds, by means of deep drains cut into the sides of such hills and rising grounds, and, after collecting it into them, conveying it away by pipes,. or other contrivances, at such high levels above the wet lands as may be necessary: or where the water that produces the mischief can by means of drains, cut in the wet ground itself, be so collected as to be capable of being raised by means of machinery, it may in that way be removed from the land.

3926. The drainage of lands that lie below the level of the sea, can only be effected by the public, and by means of locks erected for the purpose of preventing the entrance of the tides, and by wind-mills and other expensive kinds of machinery constructed for the purpose of raising the stagnant water.

3927. The superficial wetness of lands, which arises from the stiff retentive nature of the materials that constitute the soils and the particular circumstances of their situations, is to be removed in most cases by means of hollow surface drains, judiciously formed, either by the spade or plough, and filled up with suitable materials where the lands are under the grass system; and by these means and the proper construction of ridges and furrows where they are in a state of arable cultivation.

3928. Having thus explained the manner in which soils are rendered too wet for the purposes of agriculture, and shown the principles on which the over-proportions of moisture may, under different circumstances, be the most effectually removed, we shall proceed to the practical methods which are to be made use of in accomplishing the business in each case.

SECT. II. Of the Methods of Draining Boggy Land.

3929. In the drainage of wet or boggy grounds, arising from springs of water beneath them, a great variety of circumstances are necessary to be kept in view. Lands of this description, or such as are of a marshy and boggy nature, from the detention of water beneath the spongy surface materials of which they are composed, and its being absorbed and forced up into them, are constantly kept in such states of wetness as are highly improper for the purpose of producing advantageous crops of any kind. They are, therefore, on this account, as well as those of their occupying very extensive tracts in many districts, and being, when properly reclaimed, of considerable value, objects of great interest and importance to the attentive agricultor. Wet grounds of these kinds may be arranged under three distinct heads: first, such as may be readily known by the springs rising out of the adjacent more elevated ground, in an exact or regular line along the higher side of the wet surface; second, those in which the numerous springs that show themselves are not kept to any exact or regular line of direction along the higher or more elevated parts of the land, but break forth promiscuously throughout the whole surface, and particularly towards the inferior parts (fig. 484 a), constituting shaking quags in every direction, that have an elastic feel under the feet, on which the lightest animals can scarcely tread without danger, and which, for the most part, show themselves by the luxuriance and verdure of the grass about them; that sort of wet land, from the oozing of springs, which is neither of such great extent, nor in the nature of the soil so peaty as the other two, and to which the term bog cannot be strictly applied, but which in respect to the modes of draining is the same. (Johnston's Account of Elkington's Mode of Draining Land, p. 19.)

3930. In order to direct the proper mode of cutting the drains or trenches in draining lands of this sort, it will be necessary for the draining engineer to make himself perfectly acquainted with the nature and disposition of the strata composing the higher grounds, and the connection which they have with that which is to be rendered dry. This may in

general be accomplished by means of levelling and carefully attending to what has been already observed respecting the formation of hills and elevated grounds, and by inspecting the beds of rivers, the edges of banks that have been wrought through, and such pits and quarries as may have been dug near to the land. Rushes, alder-bushes, and other coarse aquatic plants, may also, in some instances, serve as guides in this business; but they should not be too implicitly depended on, as they may be caused by the stagnation of rain-water upon the surface, without any spring being present. The line of springs being ascertained, and also some knowledge of the substrata, a line of drain (fig. 484 b, b) should be marked out above or below them, according to the nature of the strata, and excavated to such a depth as will intercept the water in the porous strata before it rises to the surface. The effect of such drains will often be greatly heightened by boring holes (c) in their bottom with the auger. Where the impervious stratum (fig. 485 a), that

lies immediately beneath the porous (b), has a slanting direction through a hill or rising bank, the surface of the low lands will, in general, be spongy, wet, and covered with rushes on every side (c). In this case, which is not unfrequent, a ditch or drain (d), properly cut on one side of the hill or rising ground, may remove the wetness from both. But where the impervious stratum dips or declines more to one side of the hill or eleva tion than the other, the water will be directed to the more depressed side of that stratum; the effect of which will be, that one side of such rising ground will be wet and spongy, while the other is quite free from wetness.

3931. Where water issues forth on the surface at more places than one, it is necessary to determine which is the real or principal spring, and that from which the other outlets are fed; as by removing the source, the others must of course be rendered dry. When on the declivity or slanting surface of the elevated ground from which the springs break forth, they are observed to burst out at different levels according to the difference of the wetness of the season, and where those that are the lowest down continue to run, while the higher ones are dry, it is, in general, a certain indication that the whole are connected, and proceed from the same source; and consequently that the line of the drain should be made along the level of the lowermost one, which, if properly executed, must keep all the others dry. But if the drain was made along the line of the highest of the outlets, or places where the water breaks forth, without being sufficiently deep to reach the level of those below, the overflowings of the spring would merely be carried away, and the wetness proceeding from that cause be removed; while the main spring, still continuing to run, would render the land below the level of the bottom of the drain still prejudiciously wet, from its discharging itself lower down over the surface of the ground. This, Johnston states, was the custom, until Elkington showed the absurdity of the practice of drainers beginning to cut their trenches wherever the highest springs showed themselves between the wet and the dry ground, which not being of a depth sufficient to arrest and take away the whole of the water, others of a similar kind were under the