Image from page 160 of "An encyclopædia of agriculture [electronic resource] : comprising the theory and practice of the valuation, transfer, laying out, improvement, and management of landed property, and the cultivation and economy of the animal and veg
Title: An encyclopÃ¦dia of agriculture [electronic resource] : comprising the theory and practice of the valuation, transfer, laying out, improvement, and management of landed property, and the cultivation and economy of the animal and vegetable productions of agriculture, including all the latest improvements, a general history of agriculture in all countries, and a statistical view of its present state, with suggestions for its future progress in the British Isles
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Book III, DRAINING MINES, QUARRIES, LAKES, &c. 705 sinking in tlirough the clay, as in soils of a contrary kind. Where there happen to be liollovvs or irregularities in the surface of the land, water inay often be observed to con- tinue standing in them, at a distance of but a few feet from the drain. In draining such lands, it will always be necessary, in the first place, to make a large or conducting drain at the loâ ^^â est part, or the end of the field, for the pui-pose of receiving and conveying away the water collected by the smaller collateral cuts which it may be necessary to make on each side of it. Where it suits for the purpose of dividing the land, this principal drain may be better open than covered, as by that means the mouths or outlets of the different small drains that come into it may be conveniently examined, and cleared out when necessary. 4272. The construction of the ridges in sxich soils, so that they may accord with the declivity, is a matter which must be carefully kept in view. They should in all such cases have a degree of elevation or roundness in the middle, suflScient to afford the water a ready fall into the furrows, which likewise should have such a depth and fall as may take it quickly into the drains. The ridges, besides being well laid up, should have small open drains formed in a slanting direction across them, in such a manner as to form communications with one another, and with the furrows ; by which means they are made to perform the office of drains; the water coming upon the ridges being thus readily conveyed into tlie furrows, along which it proceeds till impeded in its course by the rising of the ground or other cause ; it then passes through the open cross-drains into others where the descent is greater, and is ultimately conveyed off into the ditch, or other passage, at the bottom of the enclosure. The elevation of the ridges should probably, too, be made greater for the winter than the summer crops, as there must be much more injurious moisture at the former than the latter season. This may be easily accomplished at the time of ])loughing the land. Some useful observations on this description of drainage will be found in Marshal's work on Landed Property, and in Dr. Anderson's Treatise on Draining. Sect. VI. Methods of draining Mines, Quarries, Pits, Ponds, and Lakes. 4273. Where pits, mines, or quarries, happen to be formed at the bottom of declivities, and are inconvenienced or wholly obstructed, either in the digging or working, by the water contained in them, it may be possible, in many cases, to prevent its coming into such mines or pits, by cutting or boring into the lower parts of the porous strata i^g. 641. a). In order to accomplish this object, it will be necessary to ascertain if any
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porous stratum presents itself higher up the elevation than the place ^^â¢here the mine or pit is fonned, that may conduct the water it contains to the porous body below it; as by ctitting into such stratum, where discovered, much of the water may be drawn off and prevented from passing down. But notwithstanding the water from above may be cut off in this way, a quantity sufficient to inconvenience the working of the mine or pit may still filtrate from the sides of the porous bed, even though it may incline in the direction of the lower ground. When this is the case, it may, however, be readily taken away at some place in the bed. To accomplish this, and thereby obviate the effects of the water, the tennination of the porous stratum (fig. 641. a) below the pit must be ascertained; and where there is any mark of a natural outlet at the place, a large drain should be formed, in order to permit the water to flow off with more expedition. Where, however, there h a thick bed of some impervious substance, such as clay, placed upon Z a
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