220 HORTIGULTUKE [GARDEN STRUCTURES. prevalence of the Dutch taste, but, owing to the frequent humidity of the climate, they have in a great measure been discarded. Their disuse is perhaps to be regretted, as in some situations, particularly behind lengthened screens of trees, they form very agreeable promenades in dry, hot weather. Grass walks were made in the same way as grass lawns. When the space to be thus occupied had been prepared, a thin layer of sand or poor earth was laid upon the surface, and over this a similar layer of good soil. This arrangement was adopted in order to prevent excessive luxuriance in the grass. Edgings. Walks are separated from the adjoining beds and borders in a variety of ways. If a living edging is adopted, by far the best is afforded by the dwarf Dutch box planted closely in line. It is of extremely neat growth, and, when annually clipped, will remain in good order for many years. Very good edgings, but of a less durable character, are formed by thrift (Statice Armeria), double daisy (Bellis perennis), gentianella (Gentiana acaulis), and London pride (Saxifraga umbrosa) ; or by some of the finer grasses very carefully selected, such as the sheep s fescue (Fesluca ovina) or its glaucous-leaved variety. Indeed, any low-growing herbaceous plant, susceptible of minute division, is suitable for an edging. Edgings may also be formed of narrow slips of sandstone flag, slate, fire-clay tiles, bricks, glass, or cast- iron. An excellent form of edging tile is that invented by Mr Stevens of Trent- ham Gardens (fig. 2), which is made of a very durable kind of clay, and is remarkably neat in appearance. It is 18 inches long, 5 inches deep, and 5 inches broad, and, resting on the broad base, is held firmly FlG " 2-Stevens s Edging Tile. by the gravel used for filling up the walk. One advantage of using edgings of this kind, especially in kitchen gardens, is that they do not harbour slugs and similar vermin, which all live edgings do, and often to a serious extent, if they are left to grow large. In shrubberies and large flower-plots, verges of grass-turf, from 1 to 3 feet in breadth, according to the size of the border and width of the walk, make a very handsome edging, but they should not be allowed to rise more than an inch and a half above the gravel, the grass being kept short by repeated mowings, and the edges kept trim and well-defined by frequently clipping with shears, and cutting once a year with an edging iron. II. Garden Structures. 8. Gardener s Residence. The gardener s residence and the apartments for the workmen should be within con venient distance of each other and of the forcing-houses. The gardener s house may stand in the centre of the range of hot-houses, or it may be placed in one corner of the walled garden. In either case it should communicate on the one side with the best part of the garden, and on the other with the yard in which the garden offices are placed. 9. Walls. The position to be given to the garden walls has been already referred to under par. 3. The shelter afforded by a wall, and the increased temperature secured by its presence, are indispensable in the climate of Great Britain, for the production of all the finer kinds of outdoor fruits ; and hence, the inner side of a north wall, having a southern aspect, is appropriated to the more tender kinds. It is, indeed, estimated that such positions enjoy an in creased temperature equal to 7 of latitude; that is to say, the maan temperature within a few inches of the wall is equal to the mean temperature of the open plain 7 farther south. The eastern and western aspects are set apart for fruits of a somewhat hardier character. Where the inclination of the ground is considerable, and the presence of high walls would be objectionable, the latter may be replaced by sunk walls. These should not rise more than 3 feet above the level of the ground behind them. As dryness is favourable to an increase of heat, such walls should be either built hollow, or packed behind to the thickness of 3 or 4 feet with rubble stones, flints, brickbats, or similar material, thoroughly drained at bottom. For mere purposes of shelter a height of 6 or 7 feet will generally be sufficient for the walls of a garden, but for the training of fruit trees it is found that an average height of 12 feet is most suitable. In gardens of large size the northern or principal wall may be 14 feet, and the side walls 12 feet in height ; while smaller areas of an acre or so should have the principal walls 12 and the side walls 10 feet in height. As brick is more easily built hollow than stone, it is to be preferred for garden walls. A 14-inch hollow wall will take in its construction 12,800 bricks, while a solid 9-inch one, with piers, will take 11,000; but the hollow wall, while thus only a little more costly, will be greatly superior, being drier and warmer, as well as more substantial. Bricks cannot be too well burnt for garden walls ; the harder they are the less moisture will they absorb. The darker colour they acquire when the process of burning is prolonged is also more in harmony with the surrounding objects. At one time brick walls were preferred on account of the facility they afforded for training trees, but now cast-iron studs (fig. 3) or some times nails are placed in the wall during its erection, being pushed into the joints before the mortar becomes set, and ranged in straight lines, both vertically and hori zontally; for peaches, &c., they are placed 9 inches apart, and for pears, &c., 15 inches. The trees are fastened to them by soft liga tures of twine or matting, which should FlG - 3- Cast-Iron be twisted after being tied to the stud or Wal1 Stud - nail, so as to prevent contact between the branch and the metal. Many excellent walls are built of stone. The best is dark-coloured whinstone, because it absorbs very little moisture, or in Scotland Caithness pavement 4 inches thick. The stones can be cut (in the quarries) to any required length, and built in regular courses. Stone walls should always be built with thin courses for convenience of train ing over their surface. Concrete walls, properly coped ami provided with a trellis, may in some places be cheapest, and they are very durable. Common rubble walls are the wors of all. The coping of garden walls is important, both for the preservation of the walls and for throwing the rain-water off their surfaces. It should not project less than from 2 to 2-i- inches, but in wet districts may be extended to 6 inches. Stone copings are best, but they are costly, and Portland cement is sometimes substituted. Temporary copings of wood, which may be fixed by means of per manent iron brackets just below the stone coping, are extremely useful in spring for the protection of the blos soms of fruit trees. They should be 9 inches or a foot wide, and should be put on during spring before the blossom buds begin to expand ; they should have attached to them scrim cloth (a sort of thin canvas), which admits light pretty freely, yet is sufficient to ward off ordinary frosts ; this canvas is to be let down towards evening, and drawn up again in the morning. These copings should be removed when they are of no further utility as protectors,
so that the foliage may have the full benefit of rain and
