The depth to which the water table should be withdrawn depends, not at all on the character of the soil, but on the requirements of the crops which are to be grown upon it, and these requirements are the same in all soils, consequently the depth should be the same in all. What, then, shall that depth be? The usual practice of the most experienced drainers seems to have fixed four feet as about the proper depth, and the arguments against anything less than this, as well as some reasons for sup posing that to be sufficient, are so clearly stated by Mr. Gisborne that it has been deemed best to quote his own words on the subject: "Take a flower-pot a foot deep, filled with dry soil. 'Place it in a saucer containing three inches of water. 'The first effect will be, that the water will rise through "the hole in the bottom of the pot till the water which "fills the interstices between the soil is on a level with the "water in the saucer. This effect is by gravity. The 66 upper surface of this water is our water-table. From it 66 water will ascend by attraction through the whole "body of soil till moisture is apparent at the surface. Put "in your soil at 60°, a reasonable summer heat for nine "inches in depth, your water at 47°, the seven inches' "temperature of Mr. Parke's undrained bog; the attracted "water will ascend at 47°, and will diligently occupy "itself in attempting to reduce the 60° soil to its own temperature. Moreover, no sooner will the soil hold "water of attraction, than evaporation will begin to carry "it off, and will produce the cold consequent thereon. "This evaporated water will be replaced by water of at "traction at 47°, and this double cooling process will go on till all the water in the water-table is exhausted. Supply water to the saucer as fast as it disappears, and "then the process will be perpetual. The system of saucer. "watering is reprobated by every intelligent gardener; it "is found by experience to chill vegetation; besides which, 66 66 "scarcely any cultivated plant can dip its roots into stag 66 "nant water with impunity. Exactly the process which we have described in the flower-pot is constantly in 66 operation on an undrained retentive soil; the water"table may not be within nine inches of the surface, but "in very many instances it is within a foot or eighteen "inches, at which level the cold surplus oozes into some "ditch or other superficial outlet. At eighteen inches, "attraction will, on the average of soils, act with consid"erable power. Here, then, you have two obnoxious "principles at work, both producing cold, and the one "administering to the other. The obvious remedy is, to "destroy their united action; to break through their line "of communication. Remove your water of attraction "to such a depth that evaporation cannot act upon it, or "but feebly. What is that depth? In ascertaining this "point we are not altogether without data. No doubt "depth diminishes the power of evaporation rapidly. Still, as water taken from a 30-inch drain is almost invariably two or three degrees colder than water taken from four feet, and as this latter is generally one or two degrees "colder than water from a contiguous well several feet "below, we can hardly avoid drawing the conclusion that "the cold of evaporation has considerable influence at 30 "inches, a much-diminished influence at four feet, and little 66 or none below that depth. If the water-table is removed 66 to the depth of four feet, when we have allowed 18 "inches of attraction, we shall still have 30 inches of de"fence against evaporation; and we are inclined to be"lieve that any prejudicial combined action of attraction "and evaporation is thereby well guarded against. The 'facts stated seem to prove that less will not suffice. "So much on the score of temperature; but this is not "all. Do the roots of esculents wish to penetrate into "the earth at least, to the depth of some feet? We be"lieve that they do. We are sure of the brassica tribe, "of grass, and clover. All our experience and observation 66 deny the doctrine that roots only ramble when they are "stinted of food; that six inches well manured is quite "enough, better than more. Ask the Jerseyman; h "will show you a parsnip as thick as your thigh, and as "long as your leg, and will tell you of the advantages of "14 feet of dry soil. You will hear of parsnips whose "100ts descend to unsearchable depths. We will not "appeal to the Kentucky carrot, which was drawn out "by its roots at the antipodes; but Mr. Mechi's, if we "remember right, was a dozen feet or more. Three years 66 ago, in a midland county, a field of good land, in good "cultivation, and richly manured, produced a heavy crop "of cabbages. In November of that year we saw that "field broken into in several places, and at the depth of K four feet the soil (a tenacious marl, fully stiff enough for brick-earth) was occupied by the roots of cabbage, not sparingly-not mere capilla-but fibres of the size of "small pack-thread. A farmer manures a field of four or "five inches of free soil reposing on a retentive clay, and sows it with wheat. It comes up, and between the ker"nel and the manure, it looks well for a time, but anon it sickens. An Irish child looks well for five or six years, but after that time potato-feeding, and filth, and hard"ship, begin to tell. You ask what is amiss with the ་་ wheat, and you are told that when its roots reach the 'clay, they are poisoned. This field is then thorough"drained, deep, at least four feet. It receives again from "the cultivator the previous treatment; the wheat comes "up well, maintains throughout a healthy aspect, and gives a good return. What has become of the poison? "We have been told that the rain water filtered through "the soil has taken it into solution or suspension, and has "carried it off through the drains; and men who assume "to be of authority put forward this as one of the ad"vantages of draining. If we believed it, we could not 66 "advocate draining. We really should not have the face "to tell our readers that water, passing through soils con "taining elements prejudicial to vegetation, would carry "them off, but would leave those which are beneficial be "hind. We cannot make our water so discriminating; the "general merit of water of deep drainage is, that it con"tains very little. Its perfection would be that it should "contain nothing. We understand that experiments are "in progress which have ascertained that water, charged "with matters which are known to stimulate vegetation, "when filtered through four feet of retentive soil, comes 66 out pure. But to return to our wheat. In the first case "it shrinks before the cold of evaporation and the cold of 66 water of attraction, and it sickens because its feet are "6 never dry; it suffers the usual maladies of cold and wet. "In the second case, the excess of cold by evaporation "is withdrawn; the cold water of attraction is removed 66 out of its way; the warm air from the surface, rushing "in to supply the place of the water which the drains re66 move, and the warm summer rains, bearing down with "them the temperature which they have acquired from the upper soil, carry a genial heat to its lowest roots. "Health, vigorous growth, and early maturity are the "natural consequences. 66 * * * * * * "The practice so derided and maligned referring to "deep draining has advanced with wonderful strides. “We remember the days of 15 inches; then a step to 20; a "stride to 30; and the last (and probably final) jump to 50, a "few inches under or over. We have dabbled in them all, generally belonging to the deep section of the day. We "have used the words 'probably final,' because the first "advances were experimental, and, though they were jus "tified by the results obtained, no one attempted to ex plain the principle on which benefit was derived from "them. The principles on which the now prevailing "depth is founded, and which we believe to be true, go 66 66 66 "far to show that we have attained all the advantages "which can be derived from the removal of water in "ordinary agriculture. We do not mean that, even in the "most retentive soil, water would not get into drains "which were laid somewhat deeper; but to this there "must be a not very distant limit, because pure clay, lying "below the depth at which wet and drought applied at "surface would expand and contract it, would certainly "part with its water very slowly. We find that, in coal "mines and in deep quarries, a stratum of clay of only a "few inches thick interposed between two strata of per"vious stone will form an effectual bar to the passage of water; whereas, if it lay within a few feet of the surface, it would, in a season of heat and drought become 66 as pervious as a cullender. But when we have got rid "of the cold arising from the evaporation of free water, "have given a range of several feet to the roots of grass "and cereals, and have enabled retentive land to filter "through itself all the rain which falls upon its surface, 66 we are not, in our present state of knowledge, aware of "any advantage which would arise from further lowering "the surface of water in agricultural land. Smith, of "Deanston, first called prominent attention to the fertiliz"ing effects of rain filtered through land, and to evils pro"duced by allowing it to flow off the surface. Any one "will see how much more effectually this benefit will be "attained, and this evil avoided, by a 4-foot than a 2-foot แ drainage. The latter can only prepare two feet of soil "for the reception and retention of rain, which two feet, "being saturated, will reject more, and the surplus must 'run off the surface, carrying whatever it can find with it. "A 4-foot drainage will be constantly tending to have four "feet of soil ready for the reception of rain, and it will "take much more rain to saturate four feet than two. "Moreover, as a gimlet-hole bored four feet from the sur face of a barrel filled with water will discharge much |