Slips and subsidences are induced in embankments by the material being deposited when the soil is dry, and in every state of humidity from dampness to saturation; consequently the earth settles unequally, is denser in parts, and a stratification is caused as if it were composed of dissimilar earths. Should any soil be deposited in the same condition throughout, and be punned or rammed in layers, it becomes as near its original texture as is possible to quickly attain; but in depositing railway embankments, which cannot be punned or rammed, the perfect incorporation of any soil is not effected by the simple operation of tipping from a spurn head, and stratification of earth is disadvantageous, inasmuch as the layers may not be homogeneous, and in railway embankments are, with a few exceptions, in a different state owing to changes in the character of the soil, the effects of weather, mode of excavation, and in a lesser degree the height and length of the lead or distance from the cutting to the tip; the stratification, therefore, becomes varied and irregular, and depressions are formed which may hold water, and none should be permitted to accumulate in or upon a freshly tipped embankment, for then it is in its most permeable condition, and in retentive soil especially the existence of a wet place may cause it to become so deteriorated that it cannot be made stable without being drained, and when the earth is liable to become alternately very wet and dry, every means must be taken to lessen the deleterious effects. Provided an embankment is tipped of one kind of earth, although it will be in a more open state than the solid unexcavated ground, the slopes given to it are flatter than the angle of repose, the weight brought upon it does not exceed the safe load, that it is deposited upon level ground in regular and equal particles and the soil of ordinary character, there is no reason that it should slip or subside unequally if it be not undermined by aqueous action. Under these conditions settlement would be equal, or nearly so, and as all deep embankments must necessarily subside from about 10 to 40 per centum, and in extreme cases one-half, the object to be gained is to cause the settlement to be even and regular towards the centre. Benching the ground so as to prevent a movement of the toe, does not aid equal settlement nor keep the portion of an embankment above the level of the ground from spreading, except from the resistance offered by the cohesion and friction of the soil; whereas, if the ground slopes inwards towards the centre the earth has a tendency to rest and come together, and therefore not to slip upon the slopes. This system is subsequently referred to.