10 



The FARMER'S MAGAZINE. 



the surface, and evaporated, it must produce cold. Well 

 now, gentlemen, suppose you had to drain a piece of land, 

 and this [pointing to the light line in the diagram] was the 

 water-level, where actual water existed as water, the land 

 would take up by capillary attraction many inches of 

 water that would not run out of it afterwards. _ It is quite 

 clear that that would bring it within a certain distance 

 from the surface ; but it is equally clear that, if this water 

 comes too near the surface, and evaporates, it will produce 

 cold. The consideration of the proper depth of the 

 drains, then, appears to depend partly on the degree of 

 power of the soil to raise the water beyond the water- 

 level ; and, in order that a soil luay be a workable soil, 

 the consideration of the proper depth of the drains 

 must be determined with reference to the force which 

 the soil exerts in raising the water from be- 

 low, as well as to the resistance, in time, which it offers 

 to the passag? of the water through it. _ Now there 

 is one point of very considerable interest, the importance of 

 whicli has I think been too much overlooked, viz., as to the 

 depth to which water will penetrate into the earth or soil. 

 Are there no limits either as to distance- or time? What 

 auswer should we give to the question — " How far will water 

 penetrdte into soils ?" Upon a careful consideration of this 

 question, I think that the following answer will, in terms 

 sufficiently simple, express a general law which governs all 

 cases : " Until the resistance to its downward passage equals 

 the pressure from above." If the soil be porous, the water 

 from above will pass down until it reaches the water-level ; 

 and when it reaches the water-level, it meets with opposition 

 and begins to rise. But where is the point in a clay-soil — a 

 homogeueous clay-soil — at which the water will issue ? We 

 cannot talk of a water-level in clays where no water can be 

 found, even at a depth of fifty or sixty feet. But some soils 

 like these are those precisely which most require draining 

 from surface-water. There is a depth in these soils beyond 

 which surface-water will not penetrate; and this depth 

 will vary with the varying fineness and tenacity of the soil. 

 These considerations ought, therefore, to exert their proper 

 influence on the art of the prdCtical drainer. Let me here 

 observe that a vast variety of the soils which are called 

 by farmers clay-soils, are not clay-soils. If you show me a 

 soil which requires an admixture of forty or fifty per cent, of 

 sand before it will make a brick, I will admit that to be a clay- 

 soil ; but when a soil will make a brick without any admixture 

 of gaud, I cannot admit it to be a real clay-soil. The question 

 of drainage therefore, we see, in depth and distance, depends 

 on the fineness of the particles and pores of the soil; 

 the amount of capillary attraction, and last, though not 

 least, the amount o( resistance a soil offers to the 

 passage of a given quantity of water in a given time. Let 

 me here remark that one great element appears to me 

 to have been very much neglected in all discussions on 

 drainage. I say this without intending any disparagement of 

 the admirable lectures which we have had on this question, I 

 mean that this element of time has not been s'ufficiently taken 

 into consideration. A friend of mine, who is present, has 

 tried soaie experiments for me, illustrating this subject. He 

 has got a clay on the top of one of bis hilly farms, in which 

 he has sunk fifty feet without getting any water. At my re- 

 quest, some trial-holes five or six feet deep were sunk in this 

 clay, the upper rim of the holes being a little raised, to pre- 

 vent water entering directly at the surface. The object in 

 view was to find where and when the surface-water would 

 enter the pits, under rain- falls of different quantities. Under 

 these conditions it was found that, when there fell a large 

 amounts of rain in a short time, the water began to ooze into 

 the pits about one foot from the surface, the resistance to the 

 further passage of the water downwards being at that point 

 sufficient to prevent its further descent with sufficient rapidity. 

 On the other hand, when the rain-fall extended over a much 

 greater length of time, and was consequently more gradual, 

 the water was found to penetrate to the depth of two feet, 

 which was the lowest depth observed. I think a fair deduc- 

 tion from these experiments must be allowed by all to be, 

 that " the degree of resistance of a soil to the passage of a 

 given qnantity of water in a given time ought to have its 

 proper mfluence in regulating both the depth and the distsnce 

 of drains." Another conclusion which I think we must 

 inevitably draw from these facts is, that the assertion that 

 deep drains always run the first is not always correct. If this 



clay-land had been drained at one foot depth and at two feet 

 depth, it is apparent that, under the condition of a rapid and 

 heavy fall of rain, the drain at one foot deep would have run 

 the first, and that, besides, a considerable quantity of water 

 would have also escaped by simply running over the surface cf 

 the land into the nearest ditches. The effect of varying 

 amount of rain-fall in a given time is easily illustrated. I 

 have here a glass vessel filled with soil, having three apertures 

 — one near the bottom, one in the middle, and one some dis- 

 tance from the top. If I pour in water at such a rate that the 

 pores of the soil will permit it to percolate through them as 

 fast as I pour in, the water will descend to the bottom, will 

 then rise, and will issne from the lowest opening first. If I 

 pour in more water than the lowest aperture or drain c?in dis- 

 charge, the water will rise in the soil, and at length issues at 

 the middle drain. If I continue still to pour in an increasing 

 quantity, the water will rise to the top drain ; and all three 

 will discharge their respective quantities of water. If I now 

 discontinue pouring in water, you will observe that the upper 

 drain first ceases, then the middle one, and subsequently the 

 last [Experiment performed]. This is the ordinary state and 

 condition of porous soils. It is, however, as before stated, 

 different in those soils which offer greater resistacce to the 

 passage of water through their pores. Even with this same 

 soU, in which you have seen the lower drain run first, the fact 

 would be reversed if I were to pour in water faster than the 

 soil could permit it to percolate. I will now pour in the 

 water with some rapidity, when you will see the upper drain 

 run first [Experiment performed] (cheers). This last 

 case is strictly analogous to the results obtained by my 

 friend Mr. Hatfield, where he observed that the 

 heaviest rain issued at the shallowest depth. It is, 

 therefore, a question of the rapidity with which water 

 will percolate through the soil ; and I state it to be my deli- 

 berate opinion that, unless you pay sufficient attention to the 

 time which water will occupy in going through the soU, you 

 cannot drain upon scientific principles. There is another point, 

 gentlemen, which I wish to introduce. It is one that I approach 

 with great diffidence; but I must say that it is just possible 

 to have a mania for drainage, and it has often occurred to me 

 that in some cases it would be well if instead of further drain- 

 ing there were irrigation (Hear, hear). I would suggest that 

 there is such a thing as natural overdrainage ; that I have 

 seen such a thing, in such soils as the sands resting on 

 chalk, in the district between Bury St. Edmund's and Brandon 

 in Suffolk. Has there been no such thing as overdraining 

 artificially ? I would submit for the consideration of practical 

 farmers the inquiry, whether there be not many cases in which 

 the land of this country is drained too much. It is a well- 

 known fact — I cannot doubt that it is well known to most 

 present — that if you have a piece of fallov land exposed to the 

 action of the atmosphere, and have another piece of land under 

 crop (say vetches or winter tares), when you come to plough 

 them up you will find the latter quite dry and hard, compared 

 with the former (Hear, hear). This difference is accounted for 

 by the fact that every leaf of the vetch has its little root or 

 tube with ramifications running downward into the soil, and 

 that all the moisture of the soil is brought up by the roots 

 to the surface, where it evaporates by the leaves of the plant. 

 This may perhaps account for the difficulty often experienced 

 in getting a good crop of turnips after tares. But does not 

 the evaporation from the leaf and the absorption likewise of 

 water by the roots of the plants, as in the case of grass and 

 meadow lands, seem to point to the necessity of more .vater 

 than in ordinary arable land ? And in the case of the con- 

 stant evaporation from grass-land by the leaves ana roots, 

 may not the water level, without danger of injury from stag- 

 nant water, be allowed to approach a little nearer the surface 

 than in arable-land? It is the opinion of many practical men, 

 and I submit it to you with great diffidence, that some grass- 

 lands may have been over-drained— t\i&i the water has been 

 taken away too deeply from them. It is one thing to remove 

 an excess of water ; it is another thing to take away wl.at is 

 necessary for crops ; and therefore any invariable depth — any 

 depth, that is, like the laws of the Medes and Persians, to be 

 observed in all cases, and in all varieties of soil— is, in my 

 judgment, founded in error (Hear, hear). Well, gentlemen, it 

 was not my intention to deliver alon°r lecture this evening, but 

 simply to present the points which I ha>.e kid before you. I 

 have spoken of the rate at which water will descend throi'gh 

 the soil. That is a question which must be determined by 



