Springs in retentive soils

1235. Springs. Where the upper stratum is porous in some places, and retentive in others, and on a retentive base, the water, in its progress along the porous bed or layer, will be interrupted by the retentive places in a great variety of ways, and there accumulating will burst through the upper surface in the form of springs, which are more injurious than surface-water, as being colder, and generally permanent in their operation. Hence the origin of under-draining in all its varieties of collecting, extracting, and conveying water.