soil, and the form of the slope it assumes is not a straight line; that most usually approached by sand or gravel or a granular soil consisting of particles of the same character, although the lower part of the slope may be flattened consequent upon the erosion of the finer particles which crumble and become deposited at the base. As a rule, the greater the cohesion of the soil the more curved is its natural slope, the greatest pressure being at the base where the inclination is flatter, and is steeper towards the top, as the ground may be held together by cohesion at a vertical face. The harder and looser the particles the straighter will be the slope, and if the ground gradually increases in firmness it will usually be nearly straight; but if the contrary condition exists, the natural slope will be flatter towards the base although nearly vertical for a few feet from the top. As a proof how quickly clay becomes less stable and loses its cohesive power with the usual quantity of moisture in it, when first tipped it may assume a slope of 1 to 1 TO 1½ to 1, but upon exposure to the weather, which causes the lumps to waste away and the clay to swell from moisture and other agencies, the firmest clay in cuttings and embankments may be said to be unstable until a slope of at least 1½ to 1 is reached in moderate depths, and 2 to 1 TO 3 to 1 in high embankments or deep cuttings. In all earths the chief cause of movement of earth is water, and the main questions to be decided are so far as regards the inclination of the slope. 1. Should the surfaces of a cutting be drained and protected and be excavated to a comparatively steep slope; or,