Agricultural drainage : a retrospective of forty years experience / J. Bailey Denton.
- John Bailey Denton
- Date:
- 1883
Licence: Public Domain Mark
Credit: Agricultural drainage : a retrospective of forty years experience / J. Bailey Denton. Source: Wellcome Collection.
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![To reduce the effect of evaporation to tangible figures, I may state that every gallon of water carried off from the soil by evaporation robs the soil of as much heat—heat, remember, which is beneficial to vegetation—as would raise 5^ gallons of water from freezing to boiling point. You cannot be surprised, therefore, that saturated lands within reach of the sun or wind should be called cold as well as wet. Heat conveyed Heat will not pass downwards in water, and, if the soil is saturated, water and air. warmth of the atmosphere cannot penetrate it. Heat is propagated in water by circulation, that is, by the upward movement of the heated particles, and the downward movement of the colder ones to take their place. Heat is conveyed to a soil by the circulation of the air and water through its recesses, and this fact, considered in relation to what I have before said, will help to explain how it is that water occupying the interstices of the subsoil by capillary attraction, is forced downwards by descending rain, and an improved temperature gained to the subsoil. Dew. What part dew and atmospheric moisture take in underground circulation we cannot so precisely state, but it may be safely believed, that when air highly charged with moisture passes through the earth, it must, by contact with the subsoil, part with large quantities of moisture for the benefit of vegetation. It is this which gives a freshness in dry weather to the grass above mole-tracks, and makes the courses of drains so distinguishable on the surface.—From the writer's lecture entitled '■'■The theory of under-drainage as accepted by a practical ftian 1865.] As the denser clays are soils of less productive value, and therefore susceptible of less increase in renting return by drainage than clays of a milder description, there are many owners of such clay lands, who, while approving the principle of deep drainage, are disposed to take the view of the late Sir Robert Peel, who, addressing Mr. Gisborne, said:— The late Sir I can conceive a case in which, if you had a Hmited sum to expend Robert Peel's (say 4/. per acre), the nature or the ground might be such that the compromise. increased closeness might compensate for diminished depth; I mean, for instance, that drains 18 feet apart and 3 feet deep might be more effectual than drains 25 feet apart and 4 feet deep. It is utterly untrue that I am dissatisfied with the experiment of deep drainage.* Now we all know that there are thousands of acres lying on the Lias, Oxford, Kimmeridge and London clays, and I believe I may add the [* Sir Robert Peel added : If I had a field in my own occupation of stiff clay I should place close drains 21, or perhaps 18, feet apart; but I should prefer 4 feel, notwithstanding the additional expense, to 3 feet.—April, 1852.](https://iiif.wellcomecollection.org/image/b21782568_0024.jp2/full/800%2C/0/default.jpg)
