IRRIGATION.

A hasty inspection of irrigation and draining would lead to the belief that they are founded on opposite principles. It is seen that draining deprives the land of water, and that irrigation, on the contrary, supplies it with water. It is obvious that the great object of draining, and particularly of furrow-draining, is to present surface water which descends through the upper soil to the retentive substrata below it, with frequent opportunities of egress; and it is also obvious, that the great object of irrigation is to supply the upper soil, the firm foundation on which plants rear their superstructures, as much of surface-water as it can retain, for the purpose of promoting increased vegetation. Notwithstanding this apparent difference in principle between them, both induce similar effects, but the origin of which, lying deeper than the surface of the ground, might easily escape the notice of superficial observers. Both operations, in the first place, are meant to prevent all stagnation of water in the upper and under soils; both in fact create currents of water in the soil; and these circumstances are of themselves quite adequate to explain the effects of draining and irrigation on the same principle, and for the same purpose,—the promotion of vegetation. It has been found that all plants usually cultivated in agriculture cannot survive in stagnant water, and that in it their places are taken by others of a coarse nature. Now, aqueous meteors are generated in the atmosphere, and afterwards fall on the ground, and reach plants by the absorption of the soil in large quantities, and would stagnate there, were draining not to draw off the superfluous water unnecessary to vegetation in sensible currents, and prevent its stagnation. In like manner, although irrigation presents a copious flow of water to the soil; yet it provides the means of drawing off the redundancy in sensible currents, and preventing stagnation. As draining has the effect of rendering retentive subsoils porous, so irrigation is practised with most effect on porous soils. In short, so dependent are irrigation and draining on each other, that the former acts most beneficially only in conjunction with the latter. Thus the principle which is common to draining and irrigation is the prevention of the stagnation of water; and although of a negative character, it affords sure outlets to the superabundant moisture, and directly promotes vegetation.

The principle on which land is irrigated being thus explained, let us see how it may be made to operate practically, how land is really irrigated. There are four ways of irrigating land with water; and in order to preserve a command over its motions, it must in all cases enter the land to be irrigated at a higher level than where it leaves it.
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This disposition of materials is the only way to make water move in a sensible and equable current, líŕ, One kind of irrigation is called Bed-work Irrigation, which is the most efficient kind by which currents of water can be applied to level ground. 2<7, Another kind is called Catch-work Irrigation, which is suited to uneven ground. 3d, A third gets the name of Subterraneous Irrigation, from the water being supplied upwards to the surface through drains in the subsoil. Ath, And the fourth kind is called Warping, when the water is allowed to stand over a level field till it has deposited the mud it contains.

Several particulars require deliberate consideration before determining on forming any kind of water-meadow. The vicinity of a river is a requisite particular, not so much on account of the supply of water, for that may be obtained in winter beside a mountain torrent or a lake, but on account of the fertilizing matter which is generally suspended in the waters of a river. Hence a river, flowing through an alluvial and cultivated country, is preferable to one through a mountainous and rocky country. An ample supply of water is absolutely necessary to beneficial irrigation. It is folly to incur the expense of forming the most perfect water-meadow without an ample supply of water to fill the channels to overflowing. The supply of the water must be on a higher level than the ground to be irrigated. The fall need not be more than is necessary for a pretty rapid current of water, which in ordinary cases may be ten inches or a foot for one hundred or two hundred yards, and about two feet for three hundred yards. The water, if possible, should be taken as far above the meadows as to have a sufficient fall without damming up the river. When this plan is impracticable, but only when impracticable, a dam should be thrown across the stream at such a distance above the meadow, as to secure not only a sufficient fall, but the fields on both sides of the river from inundation, whether the fields belong to different proprietors or not. For, in regard to dams across small streams which form the boundaries of farms or estates, it may not be ’rrelevant to mention that altercations have frequently arisen from supposed damages arising from inundations or infringements on the rights of waters. In every case, therefore, of constructing a dam for irrigation, it will be wise to avoid the chance of disputes, by acquiring, in the first place, the right for such an erection by purchase or otherwise. When a dam is inevitable, it should be constructed substantially. The first cost will be less than the repairing of a dam which has blown up from under or burst out at the sides. When water cannot be obtained under these pre-requisites, conjoined to an ample supply, then the formation of water-meadows at that place should be altogether relinquished. But should the requisite desiderata be available, the field to be converted into a water meadow should in the first place be thoroughly drained. The most perfect piece of workmanship as a water-meadow will be comparatively useless, unless the water which has passed through the soil to the subsoil find a free egress by drains. Without drains the water will inevitably stagnate on the subsoil, unless indeed the subsoil consists of very porous materials, such as sand, gravel, or fissured rock.

Besides the particulars enumerated, two essential rules in the formation of water-meadows should never be neglected, namely, that no part of them, however small, should be on a dead level; and that every drop of water, while irrigating, should be kept constantly in motion. These rules are founded on the very principle of irrigation which has been illustrated in the prefatory remarks. True inclined planes can be the only form of surface to which these rules will strictly apply; but although it may not be possible to stretch such planes along a great extent of surface, as ground is proverbially uneven, yet every portion of it which is watered directly from the main supply should be so exactly inclined. The spirit-level should be the vade-mecum of the irrigator, the eye being deceptive in regard to the levelness of ground; and even with that indispensable instrument, the irrigator will find the formation of a complete water-meadow on an irregular surface no easy task. Superficial observers may see little difficulty in the operation; but the practical irrigator knows how nice a thing it is to adjust irregularities of ground to the constant and equable flow of water. So great is this difficulty, that none but professional irrigators ought to attempt the formation of water-meadows, and they ought to be of established character and experience; for, as Arthur Young wisely remarks, “I should recommend, in the first instance, the employment of a professed irrigator, could the young farmer possess knowledge enough to ascertain the skill of such a man; but I have seen such gross blunders made in Norfolk by such a one, on the farms of four or five persons, and yet highly recommended and coming from Gloucestershire, that I really think a man may just as well trust to himself, with the assistance of books, as put any faith in men who are reputed skilful only in proportion to the ignorance of those who employ them. In the cases to which I allude, the ignorance was unpardonable; for, as they discovered that he drew out all his works without the assistance of a spirit level, they ought to have dismissed him. Not that such a man cannot make improvements, no one can well contrive to bring water on land without improving it; but to pay L. 4 or L. 5, or perhaps more, per acre, for using a small quantity of water to same advantage, when the same might be used elsewhere to the greatest, is, comparatively speaking, throwing away money.” 1

The first thing to be done for any water meadow is to make the conductor or drain which brings the water from the river to the meadow. The size of the conductor depends entirely on the quantity of water which the meadow requires. Its bottom, at its junction with the river, should always be as low as the bottom of the river, in order to carry away as much mud as possible to the meadows. Its course should be as straight and as near an inclined plane as possible. The stuff taken out of the conductor should be employed in equalizing its banks, or filling up irregularities in the meadow. These general directions naturally lead to the examination of the particulars of which the different kinds of water meadows enumerated consist.

I. BED-WORK IRRIGATION.

This species of irrigation is eminently applicable to level ground, and under it, as the name implies, the ground is thrown into beds or ridges. After the conductor has been brought from the river to the meadow as directed, it should be led along the highest end or side of the meadow in an inclined plane; and should it terminate in the meadow, and not have to proceed farther on to another, its end should be made to taper when there are no feeders, or to terminate in a feeder. The tapered end will retard the motion of the water, and containing, of course, less water, the water will overflow the banks of the conductor. The main drain to carry off the water after it has irrigated the meadow should next be formed. It should be cut in the lowest part of the ground at the lower end or side of the meadow. Its dimensions should be capable of carrying off the whole water used, so quickly as to prevent the least stagnation, and discharge it into the river. The stuff taken out of it should be used to fill up irregularities in the meadow. In case the river takes a turn along the lower end or side of the meadow, the turn should be used as a main drain to carry off the water, and save the expense, of cutting a drain It 1 Farmer’s Calendar, p. 295.
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may be imagined that as a portion of the water will be absorbed by the soil, the main drain need not be made so large as the conductor, merely to carry off the water that has been used; but in practice it will be found, that when the water is muddy, but little of it comparatively will enter the ground, because the sediment, acting as an impervious covering, prevents much of the water from descending into the ground. The next process is the forming of the ground intended for a water-meadow into beds or ridges. That portion of the ground which is to be watered by one conductor should be made into beds to suit the circumstances of that conductor; that is, instead of reducing all the beds over the meadow to one common level, they should be formed to suit the different swells in the ground, and should any of these swells be considerable, it will be necessary to give each side of them its respective conductor. The beds should run at or nearly at right angles to the line of the conductor. The breadth of the beds is regulated by the nature of the soil and the supply of water. Tenacious soils and subsoils, and a small supply of water, require as narrow beds as thirty feet. Porous soils and a large supply of water may have beds of forty feet. The length of the beds is regulated by the supply of water and the fall from the conductor to the main drain. If the beds fall only in one direction longitudinally, their crowns should be made in the middle; but should they fall laterally as well as longitudinally, as is usually the case, then the crowns should be made towards the upper sides, more or less according to the lateral slope of the ground. The crowns should rise a foot above the adjoining furrows. The beds thus formed should slope in an inclined plane from the conductor to the main drain, that the water may flow equably over them. The beds are watered by what are called feeders, that is, by channels gradually tapering to the lower extremities, and cut down their crowns, wherever these are placed. The depth of the feeders depends on their width, and the width on their length. A bed two hundred yards in length requires a feeder of twenty inches in width at its junction with the conductor, and it should taper gradually to the extremity, which should be one foot in width. The taper retards the motion of the water, which constantly decreases by overflow as it proceeds, whilst it continues to fill the feeder to the brim. The stuff which comes out of the feeders should be carefully and evenly laid along the sides of the beds. The water overflowing from the feeders down the sides of the beds is received into small drains formed in the furrows between the beds. These small drains discharge themselves into the main drain, and are in every respect the reverse of the feeders; that is, their tapering extremities lie up the slope, and their wide ends open into the main drain, to accelerate the motion of the departing water. The depth of the small drain at the junction is made about as deep as that of the main drain, and it gradually lessens towards the taper to six inches in tenacious and to less in porous soils. The depth of the feeders is the same in relation to the conductor. The stuff obtained from the small drains is employed to fill up inequalities in the meadow. For the more equal distribution of the water over the surface of the beds from the conductor and feeders, small masses, such as stones, solid portions of earth or turf fastened with pins, are placed in them, in order to retard the momentum which the water may have acquired. These stops, as they are termed, are generally placed at regular intervals, or rather they should be left where any inequality of the current is observed. Heaps of stones answer very well for stops in the conductor, particularly immediately below the points of junction with the feeders. Solid portions of earth are usually left in the feeders, or tough pieces of turf fastened down with wooden pins; but care must be taken to keep the tops of the pins below the reach of weeds floating on the surface of the water. These stops, however, are nothing but expedients to rectify work imperfectly executed. It must be] obvious that a perfectly-formed water-meadow should require few or no stops. The small or main drains require no stops. The descent of the water in the feeders will no doubt necessarily increase in rapidity, but the inclination of the beds, and the tapering of the feeders, should be so adjusted as to counteract the increasing rapidity. At all events notches cut into the sides of the feeders to retard the velocity of the water, is much more objectionable than stops, although some writers recommend them; but where they have been observed, the spectator may depend on having seen an imperfect water-meadow. The distribution of the water over the whole-meadow is regulated by the sluice, which should be placed at the origin of every conductor. By means of these sluices any portion of the meadow that is desired can be watered, whilst the rest remains dry; and alternate watering must be adopted when there is a scarcity of water. Each sluice should be placed according to the elevation or depression of the ground which it supplies with water. All the sluices should be substantially built at first with stones and mortar; because a carelessly constructed sluice will permit the leakage of water at all times; and should the water from the leak be permitted to find its way into the meadow, that portion of it will stagnate and produce coarse grasses. In a well formed water-meadow it is as necessary to keep it perfectly dry at one time, as it is to place it under water at another. A small sluice placed in the side of the conductor opposite to the meadow, and at the upper end of it, will serve to drain away the leakage that may haply have escaped from the head sluice. The laying out of the beds, feeders, and small drains, constitutes the nice part of the formation of a water-meadow; it constitutes the test by which the skill of the irrigator is tried; and it is impossible to acquire the skill without practice.

To obtain a complete water-meadow, the ground should be broken up and remodelled; for it is rare to find a piece of ground naturally possessing the requisite qualifications of a water-meadow. Such a remodelling will no doubt be attended with cost; but it should be considered that the first cost is the least; and remodelling the only way of obtaining the desired object of having a complete water-meadow which will continue for years to give satisfaction. To effect a remodelling when the ground is in stubble, let it be ploughed up, harrowed, and cleaned as in a summer fallow; the levelling-box employed when required, the stuff from the conductors and main drains spread abroad, and the beds ploughed into shape. All these operations, as of the farm, can be performed at little expense, and they τ form the substantial foundation of the nicer operations of the spade, the barrow, and the level. The meadow should be ready by August for sowing with grass-seeds. The seeds best suited for a water-meadow are perennial rye-grass (Lolium perenne), sweet-scented vernal grass (Anthoxanthum odoratum), crested dog’s-tail grass (Cynosuras cristatus), meadow foxtail grass (Alopecurus pratensis), rough-stalked meadow-grass (Poa trivialis), and florin (Agrostis stoloιιifera). The florin is the prevailing grass in all good water-meadows, and it makes a most delicious hay. It is best propagated by sowing the stems chopped into pieces like chaff. These grasses do not always produce^ a good crop the first year, but the rye-grass will assist to thicken the crop. Some writers, and particularly Mr Smith in his Essay on Irrigation, assert that it is of no importance what grasses are sown in water-meadows, as the most congenial kinds will in time spring up and banish all the others; but is it not better to supply the ground at once with the best grasses than wait for the extirpation of the worst? The method now described of forming a water-meadow is attended with one great disadvantage; the soft ground cannot be irrigated for two or three years after it is sown with grass-seeds.
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This disadvantage can only be avoided where the ground is covered with old turf which will bear to be lifted. On ground in that state a water-meadow may be most perfectly formed. Let the turf be taken off with the spade, and laid carefully aside for relaying. Let the stript ground then be neatly formed with the spade and barrow, into beds varying in breadth and shape, according to the nature of the soil, and the dip of the ground; the feeders from the conductor, and the small drains to the main drain being formed at the same time. Then let the turf be laid down again and beaten firm, when the meadow will be complete at once, and ready for irrigation. This is the most beautiful and most expeditious method of making a complete water-meadow, and should always be adopted where practicable, although it should at first be the most expensive.

7. The water should be let on, and trial made of the work, whenever it is finished; and the motion of the water regulated by the introduction of a stop in the conductors and feeders, where a change in the motion of the current is observed, beginning at the upper end of the meadow. Should the work be finished as directed by August, a good crop of hay may be reaped in the succeeding summer. There are few pieces of land where the natural descent of the ground will not admit of the water being collected a second time, and applied to the irrigation of a second and lower meadow. In such a case the main drain of the watered-meadow may form the conductor of the one to be watered, or a new conductor may be formed by a prolongation of the main drain; but either expedient is only advisable where water is scarce. Where it is plentiful, it is better to supply the second meadow directly from the river, or by a continuation of the first main-conductor. In some instances it may be necessary to carry a conductor over a hollow piece of ground along an aqueduct made for the purpose, called a carry, bridge. Such an aqueduct may be made either of wood, cast-iron, or stone and mortar.

As a real example of a water-meadow, such as has been described, will illustrate the several particulars specified more accurately than any imaginative case, fig. 1 is a design of one belonging to Mr Loch of Rachan in Peeblesshire, and executed in 1823 by Mr George Stephens, drainer and irrigator, Edinburgh. The design is taken from Mr

Stephens’ Practical Irrigator and Drainer, 1834 (p. 10), a work of great practical utility. The meadow, as may be seen, in fig. 1, lies on both sides of the river Biggar, and contains eight acres, partly of clay, but mostly of gravel, and both resting on a gravelly subsoil. The river supplies the meadow amply with water. The expense of straightening the river, building the dam and sluices, and forming embankments against inundations in every flood, was L. 9 per acre. The work was executed late in spring 1823, and in 1825, four hundred stones of hay per acre were cropped, worth sixpence per stone, or L. 10 per acre, and L. 1 per acre for the aftermath, from land that was not worth L. 2 per acre before being irrigated. The references to the cut are these: a is the Biggar water; b is the dam 30 inches high across it; cccc sluices in conductors; ddddd conductors; eeee feeders; f f 'ff small drains; ggg main drains; h a drain for cutting off natural springs; i a small sluice on the side of the conductor, to carry off' any leakage of water from the sluice c; h a carry-bridge or aqueduct; ll conductor to another meadow; .... stops in conductors and feeders.

II. CATCH-WORK IRRIGATION.

This kind of irrigation is only applied to sloping banks, and should never be practised where the bed-work system can be introduced, although many are tempted, by the ease and economy of its construction, to prefer it. It is quite different in its construction from the bed-work. Were the feeders placed up and down the slope at right angles to the conductor, as in the case of bed-work irrigation, the water would acquire such a momentum in its descent, as to cut the ground into ruts. No number of stops could prevent this mischief. In order to prevent it, the feeders are cut across the face of the slope in parallel rows below each other. The water overflowing from the upper feeder is caught by the one below it, and so on in succession, till at last it finds its way into a main drain or the river. Main drains are less useful in this kind of irrigation than in the bed-work, as there are no small drains necessary to open into them, the tapering ends of the feeders discharging the water equally over the margin into the river. But it is obvious, that were the feeders on the lower level to receive their whole supply of water from those above them, the sediment in the water would be chiefly deposited by the upper feeders. It is therefore requisite to give a direct communication from the conductor to each feeder. To effect this, the direction of the feeders is made at an acute angle with the conductor, and their dis ∙ tance from each other is regulated by the fall of the ground, and the nature of the subsoil. WTιere the subsoil is porous, and the fall of the ground one foot in twenty or thirty, the distance between the feeders may be made from twenty to thirty yards; but where the declivity is less, and the subsoil tenacious, the distance should never exceed ten yards. Stops should be placed in the conductor immediately be low the points of junction with the feeders; and in the feeders at regular distances, or rather where the current appears to accelerate its motion.

The expense of forming a catch-work meadow may vary from L. 3 to L∙ 5 per acre. The comparative cheapness of this kind of irrigation, induces many to adopt it in situations which ought to be occupied with bed-work irrigation.

The following design of a catch-work meadow, is taken from Mr Stephens’ work above referred to. The meadow was formed by him in 1823, on the estate of Closebum, in Dumfries-shire, belonging to Mr Stuart Menteith. The references to the cut are these: a a a, fig. 2, is the river; bb b are conductors; cec feeders; ddd main drains, and the river also acts as a main drain; e is a lake; f the dam across the river; g g are sluices in the conductors; .... stops in the conductors and feeders.
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It may frequently happen that the bed-work and catchwork systems may be beneficially united at the same fall of water. The conductor may be led along the higher ground, and give rise to a system of catch-work irrigation on the sloping ground, and terminate in the bed-work on the more level portion below. Such a compound structure may save much expense in levelling, and will make the most of the water. Instances of this compound-work may be seen at Whitehaugh in Peeblesshire, belonging to Sir John Hay, Bart., and at the Townfoot Meadow of Dolphinton in Lanarkshire, belonging to Mr Richard Mackenzie, writer to the Signet, Edinburgh.

MANAGEMENT OF WATER-MEADOWS.

The formation is not the only difficulty attending watermeadows; their good management is a nice business, and essential to the deriving of benefit from them. It must be confessed that much ignorance and negligence prevail in their management; and when the risk is considered of losing the whole of the fine herbage, and getting coarse in its stead, by bad mangement, a skilful irrigator is a character who ought to be highly appreciated. The particulars which require constant attention are, the state of the water in the river, whether there is sufficient to water the whole, or only a part of the meadow; the regulating of the sluices, so as not to permit more nor less water than the part of the meadow intended to be watered requires; the length of time the water should be allowed to remain on the meadow at different periods of the season; the proper time at wduch hay harvest and pasturage should commence and terminate; the state and nature of the soil to be irrigated,-whether porous or impervious; and the removal of all minute obstructions to the perfect irrigation of the meadow.

Every size of river is not equally suitable for irrigation. A large flowing stream, supplying sufficient water at all times, affords facilities for irrigating a part or the whole of a meadow, much better than a brook which swells and falls with every shower of rain. At the same time whatever may be the command of water, it is an error to attempt to irrigate too large a surface at one time. The attempt to force a larger quantity of water than the feeders and drains can easily convey, will end in deluging one part, whilst another will be stinted; and where there is inequality of irrigation, there will be inequality in the quantity and quality of the grass. Where there is an ample supply of water, therefore, no more ground should be irrigated at one time than can be covered equally to the requisite depth by the natural force of the water. Where the supply is short of this, which is more frequently the case, the water should, only have as much ground allotted to it as it can effectually irrigate. The intervals between the irrigations will be greater when the supply of water is scanty than when plentiful; but notwithstanding this, the effects produced on the meadow in both cases may be nearly equal, according as the weather is favourable or otherwise. The adjustment of the water by the sluices is a delicate operation under every circumstance, but particularly so when there is at times a deficiency of water. The falling or rising of the water in the river requires particular attention, and the changing of the water from one part of the meadow to another, or even from one bed to another, according to its abundance or deficiency, particular dexterity. Attention to the sluices for a short time every day, will obviate many risks of bad management. A great error may be committed by permitting the water to remain too long on the ground at a time. Unless the ground gets the air and becomes dry at stated periods, the finer grasses will be destroyed, and those of coarse quality will spring up. The watering may be con ∙ tinued for as long as fifteen days in the beginning of the irrigating season in November, but the time should be gradually lessened till March or April, when it should cease altogether. Between the intervals of watering, the land should be laid completely dry. Precautions are particularly necessary in letting the water off and on in frosty weather, frost taking quick hold of wet grass land, and throwing the plants out by the roots. The water should be let off on the morning of a dry day, and the land thus becoming dry in the course of the day, the frost will not injure the grass at night. Or, what is a still safer method, the water should be taken off in the morning and put on again at night, but few persons will take the trouble of attending so minutely to irrigation. In spring the new grown tender grass will be easily destroyed by frost, if the utmost attention be not paid to the state of the ground, either by protecting it with water, which is the surest protection it can receive, or making the ground thoroughly dry in dry weather, for dry cold never injures even young grass. There is another error which should be guarded against: when water remains too long on the ground in the spring, it generates a white scum, of the consistence of melted glue, which, when left on the grass, inevitably destroys it. Instances may be observed of water being permitted to remain on meadows from the autumn till eight or ten days before the cutting of hay. The consequences are, that the hay is of the coarsest quality, and the early bite for sheep entirely lost. It seems to be a judicious recommendation to depasture the early grass on water-meadows with ewes and lambs in March and April, and to eat it barely down before May with a heavy stock. After that the grass is allowed to stand for hay; but some recommend that it should be irrigated for a week, or a few days, to clean the pasture; whilst others think the irrigation unnecessary, and even dangerous, where sheep are kept, by tainting them with rot on the aftermath. There is no doubt that grass after being irrigated in summer, wall affect sheep with rot; but whether that which has been irrigated in May, before the hay has been cut down, will so affect them on the aftermath, is not so decidedly known. At all events it is well known that the purest water allowed to irrigate land too long at any time, but particularly in spring or summer, deposites a substance which cannot be called a sediment, nor, judging by the eye, can it even be called an impurity. It is a very fine transparent colouring on the grass, nearly resembling the fine cobwebs which float through the air in a beautiful day in autumn. From its bad effects on sheep it was observed by our forefathers, and known to them by the name of lace. It may occasionally be observed on the sides of mountains near wells, having a sparkling appearance. This lace is a rapid promoter of rot in sheep.

When it is determined to irrigate, the drains and feeders should be previously inspected, all obstructions removed, and dilapidations amended. Whatever difference of opinion may exist on irrigating at this particular period of the season, all irrigators are agreed that early irrigation in autumn produces greater effects than late, and that water [7:12:450]should be used largely during the winter, and scantily during the spring. It is possible that the benefits derived from early irrigation, especially after rains, may arise from the good effects of manure of various kinds, accumulated on the land during summer, being washed down by the rains, and mixed with the irrigating water; and it is certain that abundant irrigation in winter protects the grass from cold, as the temperature of grass under water in winter is seldom under 40° Fahrenheit. The signs of early and luxuriant vegetation observable on water-meadows in spring, when the rest of the ground may be covered with snow, evince the protective power of water. After the hay is carried off, the water is sometimes let on, to promote the growth of the aftermath, which it will no doubt do; but the rank grass encouraged by this summer irrigation will undoubtedly rot sheep. Where sheep are kept, and intended to depasture meadows, there should be no irrigation in summer. Cattle are not affected as sheep.

Should the irrigation be postponed till the autumn, in the beginning of October, the first duty of the irrigator is to see that all the feeders and drains are cleared of every obstruction, occasioned by the treading of sheep or cattle. The sluice is then drawn up, and if the water be abundant, the conductor and feeders will he filled with water in about half-an-hour. The motion of the water should first be adjusted in all the conductors; then in the feeders nearest the upper part of the meadow, and then in the lower ones in succession. The sluices regulate the water in the conductors, and the position of the stops regulates the water in the feeders. The stops should be so placed, as to cause the water to overflow the sides of the feeders, by making the openings at the sides of the stops wider or narrower. This first general inundation will shew any irregularities on the surface of the meadow; and that some irregularities will exist in the best-constructed water-meadows, it is not in the power of art to prevent. The earth in the filled-up hollows will subside, whilst the hard portions of ground which have been reduced will maintain their new shape. The irregularities should now be marked and rectified in the ensuing summer. At least three such adjustments of the water are necessary, before an irri gator should be satisfied that the meadow is properly irrigated with the requisite depth of one inch of water. This quantity of water should be continued over the meadow during October, November, December, and January, from fifteen to twenty days in succession, according as the weather is fresh or frosty, wet or dry. Between every such interval, the meadow should be laid thoroughly dry for five or six days, to give the grass air; and should the weather threaten a lengthened period of hard frost, the watering should be entirely discontinued for the time; for in thawing, the sheet of ice which covers the surface of the meadow will draw every plant of grass out by the roots, and make the soil like a mass of fermented dough. During the period of irrigation, the meadows should be regularly visited and inspected once in every three or four days, to correct any deviation from regular watering, such as may arise from collections of weeds, petty depredations of men and beasts, sticks, stones, or leaves, that may have fallen in and been detained in the conductors and feeders.

In February, great attention is required from the irrigator, as the grass will now begin to vegetate. The periods of watering must be shortened, and those of drying must be proportionally lengthened. White scum, frost, and such like evils, should be carefully avoided, as the tender grass will sensibly feel their injurious effects.

In March, the same precautions are requisite; but in the south of England, where grass is sufficiently abundant for. stock in this month, the irrigation should be dispensed with. In Scotland, irrigation may be continued all April, but with such caution, that the water should be allowed to run only five or six days at a time, and gradually lessened towards the end of the month; and in the beginning of May dispensed with altogether, and the meadow laid thoroughly dry for the summer. It should be borne in mind, that this is the most trying season for young grasses in Scotland; and also, that if watering is continued after this month, the. blades of grass will be covered with a gritty sediment, which not only injures the quality of the hay, but renders the mowing of it a difficult process.

The annual expense of keeping a water-meadow in repair may be about five or six shillings an acre. The greatest expense in keeping a meadow will be incurred in the second year, on account of the sinkings of those places which had been made up with loose earth having to be brought up to the common inclination.

III. SUBTERRANEOUS IRRIGATION.

This species of irrigation is so named, because the supply of water is derived from under the surface of the ground to the upper soil. It is only applicable to perfectly level ground, so raised above the supplying river, as to admit of a complete drainage of the field to be irrigated. This system of irrigation consists, in the first place, of ditches being formed around all the sides of the field. These act the part of conductors when the field is to be flooded, and of main drains when it is to be laid dry. The water flows from the ditches as conductors into built drains or conduits, formed at rightangles to them, in parallel lines through the fields, and it rises upwards in them as high as the surface of the ground, and again subsides through the soil and the conduits into the ditches as main drains, and thence into the river. Sluices are requisite to convey the water from the river into the ditches. This submersion, as it may be called, rather than overflow, of the ground in water, must be conducted with great care, and the water let on very calmly; for were the water let on or taken off with a forcible current, the finer particles of the soil would be detached, and carried off into the river. Indeed, however carefully the operation may be conducted, the only advantage derived from this species of irrigation is the moistening of dry ground in dry weather, which would otherwise be parched up; and in this respect the operation is best conducted in summer, and is as applicable to arable as to pasture land. It can therefore be of no importance to subterraneous irrigation, whether the water be clear or turbid, since all the sediment must be seethed through the soil, before it can possibly reach the surface of the ground.

IV. WARPING.

Warping is the overflowing of level ground with salt water within tide mark. Of course, it can only be practised near the'-sea, and most frequently it is attempted within the estuaries of large rivers, which have flowed through alluvial cultivated countries. Its immediate effect, which is highly beneficial, is the deposition of silt from the tide. To insure this deposition, it is necessary to surround the field to be warped with a strong embankment, in order to retain the water as the tide recedes. The water is admitted by valved sluices, which open as the tide flows into the field, and shut by the pressure of the confined water when the tide recedes. These sluices are placed on as low a level as possible, to permit the most turbid water at the bottom of the tide to pass through a channel in the basé of the embankment. The silt deposited after warping is exceedingly rich, and capable of carrying any species of crop. It may be admitted in so small a quantity as only to act as a manure to arable soil, or in such a large quantity as to form a new [7:12:451]soil. This latter acquisition is the principal object of warping, and it excites astonishment to witness how soon a new soil may be formed. From June to September, a soil of three feet in depth may be formed under favourable circumstances. These circumstances are summer, and the very driest season and longest drought. In winter and in floods warping ceases to be beneficial. In ordinary circumstances, a soil from six to sixteen inches in depth may be obtained, and inequalities of three feet filled up. But every tide generally leaves only one-eighth of an inch of silt, and the field which has only one sluice can only be warped every other tide. The silt, as deposited in each tide, does not mix into a uniform mass, but remains in distinct layers. The water should be made to run completely off, and the ditches should become dry, before the influx of the next tide, otherwise the silt will not incrust, and the tide not have the same effect. Warp soil is of surpassing fertility. The expense of forming canals, embankments, and sluices for warping land, is, on an average, about L. 10 an acre. A sluice of six feet in height, and eight feet wide, will warp from sixty to eighty acres, according to the distance of the field from the river. The embankments may be from three to seven feet in height, as the field may stand in regard to the level of the highest tides.

V. FLOODING.

Flooding land on the margins of lakes may be considered as a species of irrigation or warping. A successful attempt of this kind may be seen on the margin of Loch Ken, in Kirkcudbright, where 240 acres can be flooded at pleasure, when the water of the lake is in a favourable state.

In Great Britain, irrigation is practised to the greatest extent in Gloucestershire, Wiltshire, and Drumfriesshire, and partially in some other counties. In England it has long been successfully practised. Into Scotland it is comparatively of recent introduction. The estates of the Duke of Buccleuch on the Esk, Ewes, Yarrow, and Ettrick rivers, first enjoyed the benefits of irrigation to any extent in Scotland; but it is painful to observe that those water-meadows have fallen into decay from inattention. The land is now in a worse condition than if it had never been irrigated, because the very means which were used to direct the water to the land for beneficial irrigation, now form receptacles in which surface-water stagnates. Many of these meadows have since been broken up for corn culture, the high price of corn during the war having tempted their destruction. Now that live-stock remunerates the farmer better than corn, the rash step of destroying them has no doubt been by this time sincerely repented of. The water-meadows belonging to Mr Menteith of Closeburn, in Dumfriesshire, were formed about the same time, but having, since their formation, been carefully attended to, they continue to yield abundantly.

Warping is only practised in Lincolnshire and Yorkshire, in the estuary of the Humber, in the rivers Trent, Ouse, and Dun, which flow into it. The silt is an extraordinary substance. It seems to be doubted whence it comes. The Humber is clear at its mouth, and none of the rivers which flow into it bring the silt down in the floods. On the contrary, the floods invariably injure its quality, which is in the highest perfection in the driest summers. Apparently it is a mixture of sand and clay, for it cakes on drying, and will cleanse cloth of grease like fuller’s earth; and its arenaceous property is quite obvious; but its analysis by a chemist many years ago afforded no clay, the principal ingredients being a fine sand, a considerable portion of lime, some mica, and a minute portion of saline matter. It would be desirable to have a correct analysis, by some eminent chemist of the present day, of this remarkable substance.

Subterraneous irrigation is chiefly practised in drained morasses, which are apt to become too dry in summer, by closing up the mouths of the main drains, and causing the water in them to stand back in all the drains till it rises up to the soil. It was recommended by the late celebrated engineer Mr Rennie, to be practised on some extensive fens which he had drained in Lincolnshire, near Boston. To irrigate effectually in this manner, it is necessary to build the mouths of the main drains with strong masonry, and erect sluices for the retention of the water in the drains. This species of irrigation may also be attempted on any flat piece of ground resting on a gravelly bottom, by means of ditches which surround it, and which can command water from a lake or river. Turnips or potatoes, or any kind of crop, whether drilled or not, might be beneficially watered in this manner in a dry summer.

advantages of water-meadows and warping.

The advantages derived from water-meadows and warping, as stated by authors who have written on those subjects, almost exceed credibility. One author of some standing says :—“Having heard that the proprietor of an old floated meadow at South Cerney (in Gloucestershire), had dispersed of the produce of it, in the year 1795, in a way well calculated to ascertain its real value, I wrote to a person who resides on the spot, requesting him to send me a {>articular account of the product, and I received the folowing statement—In order to make the most of the spring feed, the proprietor kept the grass untouched till the 2d day of April, from which time he let it to the neighbouring farmers, to be eaten off in five weeks (which ran a week into May), by the undermentioned stock, at the following rates per head, viz. a sheep tenpence per week; a cow three shillings and sixpence; a colt four shillings. The quantity of land is eight acres.

107 wether sheep one week, . . L.4 9 2

8 cows do. . . . . 18 0

4 colts do. . . . . 0 16 0

L.6 13 2

Which for five weeks amount to . L. 33 5 10 Add three colts for three weeks, . . 116 0

Equal to L.4: 7: 8 per acre, L.35 1 10

The hay crop was, as usual, about fifteen tons, and was five weeks in growing.

15 tons, suppose at 50s. per ton, . . 37 10 0

Aftermath, 15s. per acre, . . . 6 0 0

Total, equal to L.9: 16: 5 per acre, 3 L. 78 11 10

The L. 4 :7 . ’ 8 were made at a time when other grasslands are in a dormant state, or exhibit but feeble symptoms of vegetation. But the reader will perhaps see the advantages of this art in a still stronger light, when he is told that this meadow, which is now in the occupation of a miller, was a few years ago in the hands of a farmer, who, being at variance with the miller, was entirely deprived of the use of the water for a whole winter, which, unfortunately, was succeeded by a very dry spring and summer; of course the spring feed was lost; and the whole hay crop of eight acres was only three tons.”^[1. Wright νη, Irrigation. ]

In 1802, Mr Smith laid out a water -meadow on the Paisley[7:12:452] farm, near Woburn, Bedfordshire, for the Duke of Bedford, and in 1803 its produce was as follows :—

In March, 240 sheep for three weeks, at 6d. each per week, . . . . . . L. 18 0 0

In June, mowed 18 tons hay, at L. 4 per ton, 72 0 0 In August, mowed 13f do. do. 54 0 0

In September, eighty fat sheep for three weeks, at 4d. each per week, ... 400

It then fed lean bullocks, the feeding not ì i j ∣qg θ θ valued, equal to L. 16: 13:8 per acre,^[2. Smith’s Essay on Irrigation. ] J ’

These two cases may suffice as examples of successful irrigation in England. The following cases occur in Scotland, a country, from its irregularity of surface, not naturally suited to that species of improvement. Nevertheless, in all the pastoral districts, both in the north and south, an abundance of early food in spring for ewes and lambs might be obtained, by judicious irrigation, in every valley which contains a river. In mountainous districts, the rivers may not supply the richest quality of water for irrigation, but there the soil on the margins of rivers being generally of friable loam, would be peculiarly benefited by irrigation. Such land is invariably sound for sheep when drained; and if made dry, and then irrigated, it would, early in spring, and indeed throughout the summer, afford the finest quality of the richest herbage. Water-meadows in such situations could be inclosed by themselves, and they could supply hay, if required, for the sheep-stock in winter, or be pastured at pleasure by any kind of stock during the summer.

To begin with an instance of simple irrigation in a pastoral district. “Fallaw Meadow, on a large sheep-farm belonging to Sir George Montgomery, Bart, of Macbiehill, in Peeblesshire, containing fifteen acres, was inclosed from moorland in 1816; and by collecting'the water from the surrounding sheep-drains, five acres are partially irrigated, and the remaining ten are top-dressed with the manure made from part of the produce which is consumed in winter by the sheep of the farm, in a wooden shed near the meadow. By this simple method of improvement, fifteen acres of common sheep-pasture land give the proprietor from three thousand five hundred to four thousand stones of hay per annum, averaging sixpence per stone. What an immense advantage to a sheep-farm! By this simple process of inclosing, and cutting a few small feeders and drains, the owner is enabled to provide food for his flock, when his less fortunate neighbours’ sheep must either starve or be supplied from the farm-yard; but I am afraid there are very few sheep-farmers who are so fortunate as to have any hay beyond what is requisite for stock at home. Sir George fed the same number of sheep on the farm as he did before the meadow was taken off and inclosed; and I am fully persuaded that the same improvement might be made on almost every sheep-farm in Tweeddale, for in almost all of them, there are situations where fourteen or fifteen acres might be inclosed and partially irrigated, as in every pastoral district there are numerous rills which might be easily collected and used to the greatest advantage, at a very trifling expense; so that, instead of being obliged, in snow-storms, to send fifty thousand sheep to a milder climate in the southern parts of Dumfriesshire (where owners are obliged to be at the mercy of their southern neighbours, not to mention the very serious injury the flocks receive by long and fatiguing journeys), by adopting the above system of improvement a considerable part of the losses generally sustained every year would be prevented.”^[3. Stephens’ Practical Irrigator. ]

Here is an instance of the conversion of peat-bog of little value into a water-meadow of great value. “Sir Thomas Gibson Carmichael, Bart, of Castle Craig, commenced, in the year 1817, by forming five acres with the plough and spade into regular bed-work. The land, in its natural state, was a complete bog, valued at eight shillings of yearly rent per acre. The formation was difficult, on account of the great number of deep peat-holes which were obliged to be filled up, to bring the surface to a proper level. The expense of levelling and forming the beds was L. 6 per acre, the crop of hay was 466 stones of 22 lb. per stone per acre, valued at fivepence per stone, and the after-grass at 18s. per acre, making L. 10: 12: 2 per acre of gross produce.”^[4. Ibid. ]

But the greatest promoter of irrigation in Scotland is Mr Stuart Menteith of Closeburn, in Dumfriesshire. His water-meadows comprehend both mossy and good soil. They extend to about two hundred acres, and are connected with reservoirs for containing water which can flood two hundred acres more. In his estate in Ayrshire, on the river Nith, Mr Menteith intends to form two hundred acres more of water-meadows. As a proof of the possibility of improving good land by irrigation, the catch-work meadow, represented by fig. 2, containing twenty-five acres, is a remarkable and satisfactory instance of Mr Menteith’s operations. “The land of this meadow, before being watered, was worth L 3, 10s. per acre, the expense of levelling and formation L.5 per acre. The produce of 1824 was as follows :—

200 ewes and lambs for seven weeks, at 5d. each per week, ...... L.29 3 4 300 stones of hay per acre, at 8d. per stone, 250 0 0 Aftermath, at 20s. per acre, . . . 25 0 0

L.304 3 4

Being L.12: 3: 4 per acre. The quality of the hay was equal to that of any clover-hay in the kingdom.”^[5. Ibid. ]

Another instance only, among many which exist in Scotland, shall be given of the advantages derived from common irrigation, and that is, of the bed-work water-meadow belonging to Mr Loch of Rachan, in Peeblesshire, and forming the subject of the first figure illustrating this paper. “It was formed late in the spring of 1823; the crop of hay in 1825 was judged by the neighbours to be upwards of 400 stones per acre, worth sixpence per stone, and the aftermath at L.l per acre, making the gross produce worth L.ll per acre, instead of L.2, at which the land was valued before being irrigated.”^[6. Ibid. ]

But this enumeration of the several cases of successful irrigation would be incomplete, were the water-meadows in the neighbourhood of Edinburgh omitted to be particularized. The city of Edinburgh stands on an eminence, which commands the cultivated country around it. Commanding as the situation is, water from the Crawley Spring, in the Pentland Hills, situate at seven miles distance, flows to the top of every house in the city., A ready means is thus provided of washing away all the filth of the houses and streets, which is conveyed in large sewers to the lower end of the town, where their contents arc made to irrigate many acres of naturally rich and also of poor soil. Probably upwards of 200 acres are thus irrigated for the production of grass for the cowfeeders who supply milk to the inhabitants. The rent for which these meadows are let in small portions to cowfeeders varies on an average from L.20 to L.30 per acre. Some of the richest meadows were let in 1835 at L.38 per acre; and in that season of scarce forage, 1826, L.57 an acre were obtained for the same meadows. The largest proprietor of these meadows is Mr Miller of Craigintinny, who possesses about one hundred and thirty acres; part of them, comprising land [7:12:453]now of the richest quality, having been thus watered for nearly a century, and part of them of the poorest sandy soil. The waste land called the Figget Whins, containing thirty acres, and ten acres of poor sandy soil adjoining them, were formed into water-meadows in 1821, at an expense of L.1000. The pasture of the Figget Whins used to be let for L.40 a-year, and that of the ten acres at L.60. Now the same ground, as meadows, lets for L.15 or L.20 an acre a-year, and will probably let for more as the land becomes more and more enriched. It is stated by Mr Stephens,^[7. Stephens’ Practical Irrigator, p. 77∙ ] that one hundred and ten acres of Mr Miller’s meadows, in 1827, yielded a clear profit of L.2300. The repair of these meadows costs from tĉm to fifteen shillings per acre, which is comparatively a large sum for repairs, but then they are not only watered during the winter, but for two or three days between the intervals of cutting the grass during the summer. The grass is cut from April to November, every three, four, or five weeks, according to the richness of the vegetation. It is exceedingly tender and succulent, and suitable to the production of a large quantity of milk; and were it not frequently cut, it would lie down, and soon rot at the roots.

After these striking instances of the advantages which are derivable from irrigation in a pecuniary point of view, by largely increasing the rent of land, must be mentioned the advantages which are derived from a large increase in the produce of the soil. The early grass in March, which could only be fostered by irrigation, is of the most essential use to ewes and lambs, and it offers an excellent substitute for the artificial grasses, which are usually obliged to be heavily stocked in early spring, when they are unable to bear it; and in truly pastoral districts, where artificial grasses are cultivated to a limited extent, and where old grass is generally long in springing, the breeding stock of sheep is apt to suffer in spring; but an irrigated meadow would not only supply early and abundant food, but it would enable the store-masters to raise an early crop of lambs. The large crop of fine hay which is subsequently cut from water-meadows after the pasturage of the early grass, also insures the safety of the flock, and the growing condition of the herd, in the severest winter; -whilst it at the same time supplies the manure which fertilizes, to an increasing extent, the land kept under arable culture. Whether, therefore, in pastoral districts, or in the neighbourhood of large towns, or wherever an abundant supply of river water through an alluvial cultivated country can be obtained, irrigation will certainly repay, in a short time, all the expense and trouble which are necessary for its preparation.

The advantages of warping are thus described, in a particular instance, by Arthur Young:^[8. Farmer’s Calendar, p. 387∙ ] 2 ti Mr Webster, Bank-side, has made so great an improvement by warping, that it merits particular attention. His farm of 212 acres is all warped, and to show the immense importance of the improvement, it would be necessary only to mention that he gave L.ll an acre for the land, and would not now (1805) take L.70 an acre; but he thinks it worth L.80, and some even L.100; not that it would sell so high at present; yet his whole expenses of sluices, cuts, banks, &c. did not exceed L.2500, or L.12 an acre. Take it at L.12, and add L.11, the purchase money, together L.23 an acre; if he can sell it at L.70, it is L.47 per acre profit. This is prodigious, and sufficient to prove that warping exceeds all other improvements. He began only four years ago. He has warped to various depths eighteen inches, two feet, two and a half feet, &c. He has some, that before warping was moorland, worth only one shilling and sixpence per acre, now as good as the best. Some of it would let at L.5 for flax or potatoes, and the whole at fifty shillings. He has twenty acres that he warped three feet deep between the beginning of J one and the and of September, and eighteen acres, part of which is three feet and a half deep. He has applied it on stubbles by way of manuring, for it should be noted, as a vast advantage in this species of improvement, that it is renewable at any time; were it possible to wear out by cropping or ill management, a few tides will at any time restore it. As to the crops he has had, they have been very great indeed; of potatoes from 80 to 130 tubs of 36 gallons, selling, the round sorts, at three shillings to three shillings and sixpence a tub, and kidneys at five to eight shillings. Twenty acres warped in 1794, could not be ploughed for oats in 1795, he therefore sowed the oats on the fresh warp, and scuffled in the seed by men drawing a scuffler, eight to draw and one to hold; the whole crop was very great, but on three acres of it, measured separately, they amounted to fourteen quarters one sack per acre. I little thought of finding exactly the husbandry of the Nile in England. I had before heard of clover-seed being sown in this manner on fresh warp, and succeeding greatly. He warped twelve acres of wheat stubble, and sowed oats in April, which produced twelve quarters an acre. Then wheat thirty-six bushels an acre. His wheat is never less than thirty. Six acres of beans produced thirty loads per acre, or ninety bushels; one acre, measured to decide a wager, yielded ninety-nine bushels; has had 144 pods from one bean on four stalks; and Tartarian oats seven feet high. One piece warped in 1793, produced oats in 1794, six quarters an acre; white clover and hay-seeds were sown with them, mown twice the first year; the first cutting yielded three tons of hay an acre; the second one ton, and afterwards an immense eddish. Flax forty to fifty stones per acre. Warping, it seems, brings weeds never before seen, particularly mustard, and cresses, wild celery, with plenty of docks and thistles.”

It is seen, from this statement of Mr Young, that the advantages of warping are very great; and surely so important an improvement ought not to be neglected when it can be put into practice. It is much superior in its effects to irrigation with common water, the mud creating a new soil, and not merely amending an old one. What the land intended to be warped may be, is not of the smallest consequence; a bog, clay, sand, peat, is all one, as the warp raises a soil in one summer of six to eighteen inches thick, and fills up every inequality.

Warped land at first being raw and cold, requires particular treatment. Corn is not the best crop after warping. Oats, it has been seen, may succeed, barley is never attempted, and wheat is not advisable, but sown grass-seeds thrive most luxuriantly. It is good husbandry, therefore, to sow warp with grass-seeds, and let them remain for at least two years; after them wheat will succeed, then beans, and then wheat again, but never barley on any consideration. All the green crops succeed well. In some instances, warp may contain as much salt as to hurt vegetation, in which case an exposure to the air in summer is necessary to neutralize its pernicious action on vegetation.

The quality of the water is an important element in the process of irrigation. It has been alleged that whether water is clear or turbid, irrigation is of service to grass land. There is much truth in this allegation; but it does not declare the whole truth. No doubt moisture alone is of great service to the vegetation of grass on sandy soils in a dry season; but a deposition of mud along with the moisture would surely not benefit the grass the less, nor would it injure the bare soil.

The waters of the Nile and Ganges would alone promote vegetation on their banks, the soils of which seldom experience[7:12:454] the refreshing sustenance of rain; but the inundations of those mighty rivers would not be hailed with ecstasy and gratitude on the return of every season, were their waters devoid of the fertilizing mud with which they are largely impregnated. Major Rennell states that the Ganges contains a two-hundredth part of its volume of mud, and that it thus carries 2,509,056,000 cubic feet of it per hour. In like manner, the Nile contains a hundred and twentieth part of its bulk in mud, or 14,784,000 cubic feet of it per hour. It is impossible but that the water of all rivers contains at all times, even when purest, some sediment; but it is obvious that those rivers which flow through cultivated countries must contain at all times the greatest quantity of sediment. In this way the rivers of plains must contain more mud than the rivers of mountains; and hence irrigation exhibits the most favourable results in the plains. But were no other proof of the superiority of turbid over clear water for irrigation to be found, the luxuriant produce of the water-meadows in the neighbourhood of Edinburgh, which are watered from the common sewers of that city, would s pf itself supply a convincing illustration.

Similar results could never be derived from clear water; nor is it ever found so superabundantly rich as to be necessary to be treated like the water of those meadows next the town, where holes are dug in the ground, for the purpose of catching the grosser materials with which it is charged, before it is used for irrigation.

VI. HISTORY OF IRRIGATION.

Irrigation is at least coeval in antiquity with embanking and draining. It is probably of greater antiquity. Nature had, no doubt, first taught man the art of irrigation by the inundations of rivers; but nature could teach neither embanking nor draining. Egypt was the field which was first artificially irrigated. There the fertilizing effects of the water of the Nile, after its overflow, could not fail to attract the attention of its inhabitants, and teach a simple lesson to the Egyptians, who had only to imitate nature, to secure the fertility of the soil lying beyond the reach of the inundations of the Nile. The remains of canals as capacious as the beds of rivers, which are still to be seen in that sand-desolated country, evince the gigantic efforts which had at one time been made by its inhabitants to irrigate that portion of their country upon which a drop of rain never falls to refresh its languishing vegetation. These canals traverse the whole country, and are so directed as probably to have been made to receive the water of the Nile, and conduct it to every part, to the top of the rising grounds as well as to the bottom of the hollows; the inequalities of hill and dale not being great in Egypt. The large lakes of Moeris, Behire, and Mareotis, all probably artificial excavations, had perhaps once formed extensive reservoirs to supply the canals, after the Nile had retired within its own banks. At what time all these mighty contrivances were begun, history is as silent as on the origin of the pyramids. It is, however, related that Sesostris greatly increased the number of the canals, which must have been at a period of great antiquity, for he reigned about the sixteenth century before the Christian era. Greater efforts to promote irrigation were more urgent in Egypt than in most other countries; for no rain fell in that country to cherish vegetation; and rice forming the chief food of its inhabitants, it could not be raised without a great supply of water.

It is therefore highly probable that the remains of great canals and lakes are indicative of the majestic scale with which the Egyptians had prosecuted the art of irrigation. It is, however, prudent to speak with caution on matters connected with the agriculture of ancient Egypt; for our knowledge of its husbandry is chiefly derived from hints contained in Scripture history, and not from its own historical records. The historian of Egypt, Herodotus, was a Greek, and lived at so late a period as the fifth century before the Christian era, long after the glory of Egypt had departed; whereas the Scriptures supply us with facts of Egyptian agriculture of much greater antiquity, isolated though they certainly are. Such circumstances as the following indicate the existence of irrigation in Egypt at a very remote period of the world. When Abraham and Lot journeyed together in search of a country to abide in after they had left Egypt, they agreed to separate, when they found that the land they were then in could not supply sufficient food for their united flocks and herds; and we are told that Lot chose the plain of Jordan, because it was watered as well as the land of Egypt. “And Lot lifted up his eyes and beheld all the plain of Jordan as thou comest into Zoar, that it was well watered every where, before the Lord destroyed Sodom and Gomorrah, even as the garden of the Lord, like the land of Egypt.”^[9. Gen. xiii. 10. ] Egypt never contained rivers to water it, there being only the Nile; so that the similitude between “the plain of Jordan” and “the land of Egypt,” to the mind of Lot, must have arisen from the rivers in Jordan being as numerous as the canals in Egypt; and Lot having witnessed the fertilizing powers of the water of these canals in Egypt, naturally supposed that the rivers would produce a similar effect on the plain of Jordan. The Egyptians had been in the habit of watering their gardens as well as their fields, and this they accomplished at pleasure, by raising water with a machine which they worked with the foot. Simple as such contrivances were, and they are to be seen in Egypt at this day, they could not fail to be troublesome. Dr Clarke describes the Egyptians, when raising water for their gardens, as requiring to work stark naked, or only partially covered with a blue striped shirt. When Moses, therefore, described the promised land to the Israelites, he represented it as a land which was supplied with water in a natural manner, in contradistinction to the more difficult and artificial way by the foot in Egypt: “For the land whither thou goest to possess it, is not as the land of Egypt from whence thou earnest out, where thou sowedst thy seed and wateredst it with thy foot, as a garden of herbs: But the land whither ye go to possess it, is a land of hills and valleys, and drinketh water of the rain of Heaven: And it shall come to pass, if ye shall hearken diligently unto my commandment which I command you this day, that I will give you the rain of your land in due season, the first rain and the latter rain, that thou mayest gather in thy corn, and thy wine, and thine oil.”^[10. Deut. xi. 10, 11, 13, 14. ]

By irrigation, the soil of Egypt had been rendered so fertile that Pliny compares it to that of the Leontines, formerly the most fertile part of Sicily. Certain it is that Egypt was very prolific in corn even in the days of Abraham, who had recourse to it in years of famine, and that was at least eighteen centuries before the Christian era.

Too little is known of the agriculture of the ancient kingdoms of Assyria, Babylon, Carthage, Phoenicia, and Greece, to enable any one to ascertain how they practised irrigation; but as they all had Egypt as an example in agriculture and the arts, it is probable that they had followed those practices in husbandry which were most suitable to their respective countries. The little that Xenophon says in his Anabasis of the husbandry of Persia, would lead to the belief that canals had been cut from rivers to irrigate the country after the manner of Egypt.

The sagacious Romans⅛ it is well known from the writings of their rustic countrymen, adopted irrigation on an extensive scale, as one of the best means of improving land. The [7:12:455]oldest Roman rustic writer, Cato, expressed his opinion that the way to become rich quickly was “by grazing cattle well,” and hence he gives the preference to meadows. He does not maintain that grass is the most valuable crop which the land can produce, for he only places meadows in the fifth degree of value, giving preference in this respect to vineyards, watered gardens, willow fields, and olive gardens, but that they yielded most profit in proportion to the expense attending them, and they were always ready; hence their ancient name, parata. Agreeably to this opinion, Cato recommends the formation of meadows, and particularly of water-meadows, whenever there is a command of water: Prata irrigua, si aquam habebis, potissimum facito. ^[11. Cat. cap. ix. ] Columella recommends the same precept, and enters more minutely into the kinds of soils which should be converted into water-meadows, and of the nature of the surface best adapted to them, as well as the management of the water in the time of irrigation, “Land that is naturally rich,” says he, “and that is in good heart, does not need to have water set over it; and it is better hay which nature of its own accord produces in a juicy soil, than what water draws from a soil that is overflowed. This, however, is a necessary practice when the poverty of the soil requires it; and a meadow may be formed either upon stiff or free soil, though poor, when water may be set over it. Neither a low field with hollows, nor a field broken with steep rising ground, are proper; the first, because it contains too long the water collected in the hollows; the last, because it makes the water run too quickly over it. A field, however, that has a moderate descent may be made a meadow, whether it is rich or so situated as to be watered; but the best situation is where the surface is smooth, and the descent so gentle as to prevent either showers or the rivers that overflow it from remaining long; and on the other hand, to allow the water that comes over it quietly to glide off. Therefore, if in any part of a field intended for a meadow, a pool of water should stand, it must be let off by drains, for the loss is equal, either from too much water or too little grass.”^[12. Col. lib. 2. cap. xvii. ] But none of the Roman rustic writers give directions how a røoŵr-meadow should be made, nor say any thing about the utility of sluices, although Columella gives minute directions about the formation of dry meadows. It does not appear, moreover, that they were acquainted with the raising of turf and laying it down again for meadows, because they only recommend hay-seeds from the hay-lofts and cribs to be sown, and deprecate the watering and pasturing of cattle on the new meadows till the surface becomes hard. There is no specific notice taken by any of them of how long a period meadows should be watered, if one sentence of Pliny be excepted, wherein he directs that “meadow’s ought to be watered immediately after the equinox, and the waters restrained whenever the grass shoots up into the stalk;”^[13. Nat. Hist. lib. 18, cap. xxvii. ] but there is no hint whether they should be laid dry at intervals.

Pliny alone mentions watering before the first crop of hay is cut, on the principle that wet grass, whether wetted by water or dew, is cut more easily than dry: Noctibus roscidis secari mclius. ^[14. lb. lib. 18, cap. xxviii. ] The Romans were in the custom of cutting their meadows at least twice a-year, in May and August or September, and making hay of both these cuttings; but meadows for forage were cut sometimes four times. The autumnal hay was emphatically called cordum, and being soft, and sweeter than hay come to its full growth, it was the kind most proper to be given to sheep in winter. The produce of the Roman meadows appears to have been very considerable, and it is therefore no wonder that they put such a high value on grass-land. Both Columella and Pliny estimate it a day’s work for a man to mow a jugerum and bind 1200 bundles of hay, of four pounds each. According to a calculation made by Dr Dickson, these quantities would give a produce of 265 hay stones, of 22 lb. to the stone, per acre (416 imperial stones per imperial acre), of prepared hay, besides the autumnal crop and the rakings taken up afterwards, and which may be estimated at one-half more.^[15. Husbandry of the Ancients, vol. ii. p. 321∙ ] This is not the proper place to describe the Roman method of making hay, which differed from the method of this country, but having alluded to hay having been bound in bundles, it may not be irrelevant to state that the Romans made up their hay into bundles of four pounds each before they carried it into the barns or haylofts, and that they never ricked it but in rainy weather.

Immediately after the fall of the Roman empire, agriculture declined, and was kept in a very depressed state during the middle ages, which depression, with respect to agriculture, lasted about ten centuries. It need therefore excite no surprise that the general agriculture of Italy was not much improved, from what it had been amongst the Romans, till after the revival of letters. Irrigation was perhaps the only branch of agriculture which received improvement or extension before the expiration of the dark ages; and its improvement at that time was even confined to the north of Italy. The irrigation of Lombardy to this day forms the principal feature of its agriculture. The Lombard kings, following the example of the Romans, encouraged and extended irrigation, and they were ably assisted by the inmates of their numerous and wealthy religious establishments.

Under these favourable auspices, irrigation had been extended on a great scale in Lombardy as early as 1037; and such expert hydraulic engineers had the monks of Chiare-valle become, that they were consulted and employed as such by the Emperor Frederick I. in the thirteenth century; and, ever since, so assiduous has been the care with which the agriculturists in Lombardy have preserved entire, and in good working order, their water-meadows, that at the present day no other part of the globe can exhibit that operation on so grand a scale and in such excellent order, and producing so rich a pasturage, verdant throughout the year. The largest rivers in the north of Italy, the Po, the Adige, the Tagliamento, and others, are put under requisition for a supply of water in summer and winter, for the purposes of irrigation; the whole country from Venice to Turin being almost one continued water-meadow. But there irrigation is not confined to grass-land; water being also conducted between the ridges of corn-land; in the hollows between drilled crops; among vines; and over the flats appropriated to the production of rice: and it is also used to deposite mud, in the manner of warping, where it contains sediment. Irrigation naturally passed from Lombardy into the south of France, where it is used to raise many of the more valuable productions of the soil. Spain to this day employs irrigation to so considerable an extent, that few crops are there raised without it. Some watermeadows in the neighbourhood of Salisbury, in Wiltshire, which are said to have existed from time immemorial, have led to the belief that irrigation has been practised in Britain from the time of the Romans. It is, indeed, extremely probable, that had the Romans constructed such works during their sojourn in Britain, the pastoral habits of their Saxon successors would have preserved them from destruċ-tion. But be this as it may, it is certain that irrigation after the method of Italy was not extensively introduced into Britain till the sixteenth century, when it was attempted on a large scale in Cambridgeshire, on the estate of Barbraham, by one Pallavicino, the collector of Peter’s pence in the reign of Queen Mary, but who, on the accession of Elizabeth, had the art to turn Protestant, and [7:12:456]purchase that estate with the balance of money which he had in his possession, amounting it is said to L. 30,000 or L. 40,000, and appropriate it to his own use.^[16. Vancouver’s Cambridgeshire. ] This dishonest experiment of Pallavicino was so gross, that his example as an irrigator was not followed at the time, nor indeed were many water-meadows formed in England till the end of the last or beginning of the present century. Since that time, many of them have been scientifically made both in England and in Scotland, which all have proved how profitably irrigation might be extended, and of which a few successful examples have been enumerated. As might be expected from the nature of the climates, irrigation is extensively practised in India, China, and parts of America, particularly Mexico but as the irrigation of those countries presents no features peculiarly different from that related of Egypt and Italy, it is unnecessary to enlarge upon it.

VII. THEORY OF IRRIGATION.

The theory of irrigation, as propounded by the late Sir Humphrey Davy, is given by him in these words: “Water is absolutely essential to vegetation; and when land has been covered with water in the winter or in the beginning of spring, the moisture which has penetrated deep into the soil, and even the subsoil, becomes a sort of nourishment to the roots of the plants in the summer, and prevents those bad effects which often happen in lands in their natural state from a long continuance of dry weather. When the water used in irrigation has flowed over a calcareous country, it is generally found impregnated with carbonate of lime, and in this state it tends, in many instances, to ameliorate the soil. Common river water also generally contains a certain portion of organizable matter, which is much greater after rains than at other times, and which exists in the largest quantity when the stream rises in a cultivated country. Even in cases where the water used for flooding is pure, and free from animal and vegetable substances, it acts by causing the more equable diffusion of nutritive matter existing in the land; and in very cold seasons it preserves the tender roots and leaves of the grass from being affected by frost. . . . In general, those waters which breed the best fish are the best fitted for watering meadows; but most of the benefits of irrigation may be derived from any kind of water. It is, however, a general principle, that waters containing ferruginous impregnations, though possessed of fertilizing effects, when applied to a calcareous soil, are injurious on soils that do not effervesce with acids; and that calcareous waters, which are known by the earthy deposite they afford when boiled, are of most use on siliceous soils, or other soils containing no remarkable quantity of carbonate of lime.”^[17. Quarterly Journal of Agriculture, vol. v. p. 24. ] To show the protective power of water against cold, it is only necessary to state the well-known physical fact, that water is of greater specific gravity at 42° Fahrenheit than at the freezing point of 32°; and hence water in contact with the roots of grass is rarely below 40°, a degree of temperature not at all prejudicial to the living organs of plants. Professor Rennie, of King’s College, London, has recently given another theory of irrigation. It was promulged by Μ. De Candolle of Geneva, in his Physiologic Vegetale, and his views have recently been corroborated by the experiments of M.’Macaire of Geneva, that plants exude an excretion from their roots into the soil, and that this excretion is detrimental to the healthy growth of the same kind of plants which produced it. Hence it is concluded that grasses do not continue permanently in a healthy state in the same site, because they are in time injuriously affected by their own excretions, which, encouraging the growth of plants of a different nature, such as mosses, they spring up and extirpate the grasses. It is supposed to be probable that every species of grass is not alike affected by its own, or the excrementitious matter from other grasses, and therefore some species withstand the poison longer than others. Now, the water of irrigation, in its descent through the soil and subsoil, washes away or carries off in solution the injurious excrementitious matter exuded by the grasses, and thereby cleanses the soil in which they are growing free of it. Hence the perennial verdure of irrigated grass.^[18. Agricultural Chemistry, 4to edition, p. 205. ] These theories establish four advantages which are derivable from irrigation. It supplies moisture to the soil, necessary in dry seasons and in tropical countries; it affords protection to plants against the extremes of heat and cold; it disseminates manure most minutely to plants; and it washes away injurious matter from the roots of plants.

Whichever theory is adopted, or both of them, for they are not inconsistent with each other, the benefits derivable from irrigation are purely mechanical; they have no reference to chemical action. The opinion of Sir Humphry Davy, therefore, that “in the artificial watering of meadows, the beneficial effects depend upon many different causes, some chemical, some mechanical,”^[19. Agricultural Chemistry, p. 305. ] appears very problematical. Chemical action only commences after irrigation has ceased. This conclusion will appear evident, when the following particulars have been considered.

The operation of water bringing matter into minute subdivision; the sediment which it contains when used in irrigation being minutely distributed around the stems of the plants; water protecting plants in irrigation against the extremes of heat and cold, by completely covering and embracing every stem and leaf; and the supplying of moisture to the soil, and washing excrementitious matter out of it, are all purely mechanical operations. Warping is obviously a mechanical operation. Could the hand of man distribute manure around the roots and stems of grass as minutely and incessantly as turbid water; could it place a covering of woollen manufacture upon each blade and around each stem of grass, as completely as water can embrace each plant and keep it warm; could it water the grass as quietly and constantly as the slow current of irrigation; and could it wash away injurious matter from the soil as delicately around the fibres of the roots of grass as irrigating water, there would be no need of irrigation; the husbandman could then command at will verdant pasturage for his flocks and herds throughout the year, and in the driest season. His me chanical agency would be as effective as that of irrigation. But the relative powers of things being as at present constituted, man employs irrigation as the instrument of his will, and attains the maintenance of his live-stock by inducing Nature to assist him in a work in which she undoubtedly displays her superiority over him both in indugtry and dexterity.