In Chapter VIII. soft soil or weak ground is referred to, and as in dockworks this so frequently occurs, the necessity of making every reasonable provision against undue settlement is apparent. In such foundations the weight upon them should be as equable as possible, for any excess of load will cause subsidence at that place, and a large bearing area is required which may not be easy to obtain, except by increasing the area at the back, as the face must be nearly straight, or only slightly curved, to enable vessels to get alongside, but the wall should not be the heavier in front as it will aid an overturning movement. Any dredging operations should be effected at such a distance that the stability of a wall cannot be impaired, or a slip of earth may occur, as the bared soil may commence to “blow” or run consequent upon the dredging having relieved the ground of weight and, perhaps, removed an impervious covering. A row of sheet piles inserted before dredging is commenced, if well supported in front, may be sufficient to prevent movement. In dockwork, the margin allowed to resist lateral strain being considerable, walls seldom fail by being fractured from excess of lateral pressure; but either by vertical or lateral pressure causing subsidence or the whole of a wall to slide forward upon the foundations; and not from defective form, workmanship, or materials; but from a compressive strain upon the face of a wall caused by a force tending to overturn it; and, as a rule, when a wall inclines towards the face very little more pressure will upset it. Generally the foundations are sufficiently firm to support the insistent load, and the chief cause of failure or undue movement is principally the result of slipping forward and the want of adhesion of the soil and frictional resistance of the wall upon it. How can this forward movement of the earth be prevented? Before proceeding to name some means that can be employed it is advisable to remember the cardinal principles of the construction of dock-walls to resist lateral thrust, because a structure may be so designed as to induce a movement or a slip of earth. They may be briefly stated to be as follows:— 1. That the maximum weight is not required in the front of a dock-wall but at the back, in order that the centre of gravity may be as far distant from the face as the exigencies of sound construction will allow. 2. That the centre of gravity should be as low as possible consistent with the due strength of the upper portions of a wall so as to increase the resistance to an overturning movement. 3. To have an equal load upon the ground, and to guard against any extra strain upon the foundations near the face of a wall consequent upon the lateral thrust, which has a tendency to cause a wall to overturn. 4. Particularly to provide against any forward movement either by having deep foundations, protective works at the base of a wall, or by other means.