The chief object of a protection at the toe in clay soils is to prevent the bottom of a slope being softened by a lodgment of water, or fissured by heat or drought; this may be effected without a wall; but in the case of sand or fine granular earth cuttings liable to become quicksand, support at the base is absolutely necessary, and the best way to prevent movement may be to erect a breast retaining wall at the toe a few feet in height, say 3 to 5 feet, the backing being of dry porous material such as ashes, coarse gravel, or broken stone, increasing according to the depth or height of the earthwork and quantity of water, the thickness being more than sufficient to contain the drainage waters, and not less than 1 foot 6 inches, in order that it may act as a filter and drain the slope, &c., so as to lessen the percolation of water. Sheet-piling and a backing of rubble acting as a drain 2 or 3 feet square, or a strutted timber duct, both made out of old sleepers, have been used with this object in quicksand where water rapidly percolated to and accumulated at the base. Instability of the toe may also be prevented by covering it with layers of gravel, but one of the reasons that may cause a gravel counterfort to fail in loose porous soil is that sand or mould may be washed through the interstices in the stones forming the gravel; hence a more impermeable covering is to be recommended in such a case. A toe of rammed coarse gravel or broken stone may supply the required support in the case of coarse and fine sand, when the latter is alone movable. Experiments have shown that sand rammed in layers of about 5 inches and earth mould 2 inches in thickness give the best results. The less the weight is increased by ramming the more solid the original earth. Brushwood or fascine work weighted with gravel, stone or broken bricks, and stone pitching can also be used for sandy soils, but a filtering layer must cover the sand, or the latter will be eroded. Counterforts of well-rammed natural earth may be sufficient provided the soil is firm and is made compact and uniform in texture. In otherwise stable soil, when it is known that a sand vein is the cause of a slip because of water percolating through it, it should be raked out as deeply as practicable if not too large, and the space be filled with stones, coarse gravel, or dry material forming an open drain for the water to issue without a flow of sand, thereby preventing any accumulation. When a stratum of shifting sand overlies beds of conglomerate and gravelly or clayey sand it will be necessary to support the lower portion of its slope by a wall. The wettest places in a slope should be noted and the surface be turfed or covered, and should the depth of the unstable sand exceed 5 or 6 feet, narrow benchings can be made 2 or 3 feet in width at every 5 or 6 feet of vertical height to divide the flow of water and prevent it following a continuous course.