To counteract any overturning tendency, a wall should have a large bearing area under the face portion, all projections and heavy copings should be avoided, or anything that increases the load near the face at the top. Weight and width of base and considerable depth of foundations are most important, for well designed walls when placed upon stable ground have been pushed forward simply from an insufficiently deep hold in the ground; and the load upon the earth must be within its safe bearing power. A wall should be designed so that its centre of gravity is as far from the face as practicable, and when it is constructed of stone or brick it is necessary that the joints be as strong as possible, and be capable of resisting varying strains. Should lime mortar be used it is probable it will be partly washed out, and Portland cement mortar should always be preferred upon the face, or water may percolate into the wall and even pass through it to the earth and cause slips and subsidences. Counterforts erected upon the outer face of retaining walls are much to be preferred to any placed at the back, for support at the face is what is required: in the latter case there is always a chance of their becoming separated from the main wall, although when so located at the back they are considered to lessen the lateral pressure of the earth by dividing it, but any reduction caused by friction of the soil against the sides may vary so greatly, according to the condition and subsidence of the earth, that it is prudent to disregard it, and it is well to remember that the pressure may become intensified or uneven upon the main wall by deflection and concentration caused by the counterforts, the result being the creation of weak and unduly strained places; it may therefore be better to uniformly increase the thickness of the wall. Counterforts of triangular shape on plan have been adopted in order to lessen the lateral thrust by directing it to the sides of the triangles, their bases being against the wall. It is doubtful whether the thrust of the earth so acts under the usual varying conditions of work. The necessity of mooring vessels alongside a dock or quay-wall prevents the adoption of face counterforts except to a very limited extent; however, although the form of a ship permits of only a slight batter for the upper half, the lower portion may be inclined for a few feet from the bottom. As the adoption of a batter on the face increases the area of the base of a wall and its frictional surface upon the ground, and tends to lessen overturning movement and undue strain upon the face, a dock, quay, or retaining wall having a batter is to be preferred to one with a vertical face; in fact, it acts as a triangular front counterfort, with the great advantage of being an inherent part of a wall.