. The gardener's assistant; a practical and scientific exposition of the art of gardening in all its branches. its pressure, through the upper layer, as atA, B, C. In some clay soils a bed of sand or gravel,completely saturated with water, occurs at thedepth of a few feet below the surface, withwhich it has corresponding undulations; butin places where its water is subjected to thegreatest pressure, and the stratum of clayabove it offers the least resistance, springs from. Fig. 806. it appear at the surface, or it saturates the soilso as to render it only fit for subaquatic vege-tation. Fig. 8
. The gardener's assistant; a practical and scientific exposition of the art of gardening in all its branches. its pressure, through the upper layer, as atA, B, C. In some clay soils a bed of sand or gravel,completely saturated with water, occurs at thedepth of a few feet below the surface, withwhich it has corresponding undulations; butin places where its water is subjected to thegreatest pressure, and the stratum of clayabove it offers the least resistance, springs from. Fig. 806. it appear at the surface, or it saturates the soilso as to render it only fit for subaquatic vege-tation. Fig. 806 exhibits this arrangement ofstrata: where A represents the surface soil;B, the impervious clayey subsoil; C, the waterystratum of sandy clay or gravel; D, the lowerbed of clay resting upon the rocky strata; E 20 THE GARDENERS ASSISTANT. and F, springs. Supposing the lowest portionof the stratum c, or that between E and F, tobe 4 feet lower than the highest part of thecurve on each side of it, then when the wholeis completely saturated, the upward pressurebetween E and F will be equal to about 250 the square foot. Some rocky strata, impervious to water, areinterrupted by fissures, as represented at ab(fig. 807), which are called faults by miners. Fig. 807. Some of these fissures are occupied by sub-stances which obstruct the passage of water,others with those of a porous nature. Let Arepresent a sandy stratum, B a clay one, andC and D porous strata charged
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Keywords: ., bookcentury1900, booksubjectgardening, booksubjecthorticulture
