In excavating a cutting in soil likely to slip, care should be taken that the surfaces are not strained by lumps being left upon them which are only retained by reason of the cohesion of the earth, as they will cause weak places less able to bear any pressure brought upon the slopes through the sides being deprived of continuity of support. Therefore, in such cases, the slopes should always be rough trimmed as quickly as possible after the gullet has been excavated. Also when the slope of a cutting is furrowed so that its surface consists of separate and unsupported masses of earth clinging to it, continuity of support is destroyed and the earth is more exposed to meteorological dissipation; and in non-cohesive soils such as sandy or gravelly earth, in which especially a straight and uncut surface is of importance, movement is incited. Therefore, when it is found necessary to insert open trenches in a slope, they should be at right angles to its foot, and the inserted material should be well packed so as to support the sides and to interfere as little as possible with the slope. Even in clay soils or any having considerable cohesion, trenches _diagonally or transversely_ cut in the surface are generally inexpedient as disturbing and destroying the continuity of support of the surface and increasing its exposure to the action of the weather; and although they may be temporarily effectual as drains, such division of the inclined face cannot but induce a disunited condition which will at once be apparent should the trench become choked and it miscarry as a drain; and a temporary failure may so destroy the existing delicate equilibrium as to cause movement. Such trenches should be regarded with suspicion, as any stability caused by their draining or conducting away water may be effected at the cost of continuity of support, the deterioration of the resistance of the soil to weather, and the impairment of its frictional and cohesive properties. If placed upon a slope at right angles to the formation the preceding objections are removed.