It must be allowed that a south wall receives more sun than a south-east one, but this is of little or no advantage; for before the time the sun leaves the latter, the air will be sufficiently warmed by the continued action of the sun upon it.

Construction

The next consideration is the construction; and in this the straight upright form is preferable to any other. The foundation for these walls should be dug out no deeper than the thickness of the soil on the surface, in order that no more of the wall may be lost than necessary. They must be built solid, upon a good foundation, and not formed upon arches at their bottoms, as recommended by some ; for when the roots of the trees grow out at the back sides of the walls, at their freedom, they draw a considerable quantity of rancid, unprepared juice from the earth into which they have struck or wandered; the consequence of which is, the falling of the fruit, and that frequently after it has acquired a considerable size. When walls are of any length, and the foundation not very good, they may be strengthened by projecting buttresses set at intervals; yet, if they will stand without being in danger, the face of the walls has a better appearance without them. With respect to coping, practical men have formed opinions very opposite to one another; that is to say, some assert it ought not to project more than half an inch at the most beyond the face of the wall; others, that they should project several inches, in order to throw the wet off the trees.

Others give it, or propose, a slope all one side, in order to throw the wet to the worst aspect; which, if planted with fruit trees, is very wrong - at least, according to our way of thinking, and we will tell you why. Because it is always disadvantageous to trees trained to such walls, if there can be any disadvantage in rain falling upon them - and we maintain there is - except just when the fruit is ripening; but even then, we consider they would be as well dry, and especially when they are in blossom, or the fruit is setting. At other times the little rain that falls on the foliage may be considered of advantage, upon the principle of watering the leaves of wall trees in the evening, which no one can for one moment deny refreshes them very much, and not only refreshes them, but helps to clear the said trees from insects and accumulations of dust and dirt likewise. There can be no objection whatever to a temporary coping of board, projecting a foot or thereabouts over the trees when in blossom in the spring, as it will greatly repel the perpendicular frosts, which not un-frequently happen at that time, and which are very injurious, both to the blossoms and setting fruit.

A fixed coping, projecting an inch to preserve the wall, is all that is really necessary; as if more, generally speaking, it does mischief instead of good, for it excludes light, rain, and air, from the trees in summer, and harbours, to a great extent, caterpillars and other vermin.

Materials

We now have to speak of the materials most suitable for kitchen - garden walls, the best of which is brick for the superstructure, and stone for the foundation and basement. Brick naturally absorbs more heat, and answers better, in all respects, for training trees to than stone. If the wall is not entirely built with brick, it should be faced with it on the north-east and west aspects. If durable stone can be obtained, the basement of the wall should be built of it in preference to brick. In many cases it is cheaper, and in every instance more firm and solid. The basement of all walls should be many inches thicker than the superstructure. For instance, for a brick and a half thick wall, the basement ought to be at least twenty inches. When bricks are scarce and stones are plentiful, the back part of the wall, as well as the foundation, may be built of stone, and that side of the wall having the best aspect faced with brick; but let the materials be what they may, the courses should not be laid level or horizontal, but parallel to the surface of the border, which has not only a better appearance, but answers, in every respect, better for training trees horizontally.

Wooden walls may be adopted in small gardens, but they are not so durable; and yet good fruit may be produced upon them.