507. The merely useful plant-houses described and treated of in the present work, will be only those which are required for propagating greenhouse plants, and keeping them through the winter; those used for the plants of very hot climates being considered partly useful and partly ornamental. The plant-houses used in floriculture, which are merely for use, not ornament, are principally pits, or low greenhouses; but this division also includes rough frames for protecting walls and trellises in severe weather, which are removed in summer.

598. Protected trellises are chiefly used for growing peaches and nectarines, but they may be applied to ornamental plants, or a conservative wall. The plants are "planted in a slanting position, and trained to a trellis 12 ft. wide, about 2 ft 6 in. from the ground at the back, and 1 ft. in front;" strong posts are inserted in the ground, one beyond the trellis, both in front and behind, and on these posts is nailed a frame to receive the lights; the posts and the frame being of rough wood, sawn at the Brentford Saw-mills. The details are given at length in the Appendix to Rivers's Miniature Fruit Garden, but the plan is not new having been practised many years ago at Hylands, Strath-fieldsaye, and many other places; the only new features in Mr. Rivers's plan being the employment of rough wood, and rough plate glass, in panes 2 ft. long, and 1 ft. wide; whereas, at Hylands and Strathfieldsaye, the frames and trellis were not at all unsightly, and the glass the same as that in ordinary use in hot-houses, when we saw them in 1831, when the frames in question were in full employment at both places.

509. Protected walls are of various kinds, some being protected by canvas curtains, and some by moveable glass frames.

510. Conservative wail protected by curtains. Fig. 329. shows part of a wall of this kind at Chatsworth, which has been found to answer extremely well

Section I Useful Plant Houses 323

It is divided into panels, about 27 ft. in length, and 18 ft in height, rising one above another, and divided by stone piers. The wall is flued, and covered with a wooden trellis. It has a coping, which projects about 1 ft. in front, with rods under it, on which the rings of the curtains run. Each panel has a separate rod with two curtains, which open in the middle, and draw back like window-curtains in the day, but are closed at night. The curtains are of stout hempen cloth; and in order to provide for the contrac-tion and expansion in wet and dry weather, and also to keep the curtains close together, the lower edge of the curtain is furnished with rings, which are put oyer hooks fixed on the edge of a board, which lies flat on the border, at the distance of 13 1/2 in from the wall. The outer edge of this board, which is 11 1/2 in. wide, is hinged to a rail 4 1/2 in. broad, which is made fast to stakes driven into the ground, and sawn off level with the surface. In consequence of this arrangement, when the wet weather contracts the curtains, instead of shrinking up, and exposing a part of the wall to the weather, it merely lifts up the inner edge of the board, which sinks down to its place again with the return of dry weather.

The edges of the curtain, next the piers, are made fast to slips of wood fixed to the wall, and the edges where the curtains join in the middle, overlap each other, and are tied or buttoned together, if the weather is severe. Fig. 329. is an elevation of part of the wall, showing the piers (the one rising higher than the other, as the wall ascends a sloping surface), and the curtains drawn aside.

Fig. 330. is a ground plan of the same portion of the wall; in which a is the dug border; b, the rising and falling board; c, fixed boards opposite the piers; d, a border of turf; e, a gravel walk, 6 ft. wide; and f, the lawn.

a section of the wall, the wooden coping, the curtain, and the rising and falling board

Fig. 331. is a section of the wall, the wooden coping, the curtain, and the rising and falling board.

Fig. 332. is a section of the lower part of the wall, the rising and falling board, and the ground-rail to which it is hinged, on a larger scale. A list of plants for a wall of this description, will be given in the after part of this work.