518. Ornamental structures for containing plants are of various kinds, and of every size, from the little plant cabinet to the large conservatory or winter garden. Some of these plant-houses are not provided with any means of heating; others may easily be warmed moderately; and others are regular hothouses or stoves, supplied with abundance of artificial heat, so as to imitate the hottest climate of the tropics. In the present work the designs given will be chiefly of rather small houses, which can be erected and kept up at a moderate expense; and only one or two of a costly description will be admitted.

Subsect. I. Plant Cabinets

519. Plant cabinets are the most common of all the kinds of greenhouse; nasi they are generally considered more as ornamental appendages to houses, than as peaces for rearing or keeping plants. In fact, the plants they contain! are generally grown and kept in some other place till they are ready to flower. A plant cabinet may be described as a small chamber, built on the outside of a town house or suburban villa, and constructed principally of iron, brick, or wood, but having a glazed roof, and frequently glased sides. It is generally entered by a glazed door or window from the staircase or landing. As it is chiefly intended for preserving plants which have been brought forward elsewhere, it is of no great consequence whether it is placed against the north, west, or east side of a house; though the south and south-east sides are doubtless the most favourable, and the north-east the least so. In street houses, it is often very conveniently projected from a staircase window, either. on the drawing-room floor, or the floor above.

In other cases, it is sometimes joined to the back parlour, which is made to open into it; or it is placed over the entrance porch; and, occasionally, it forma a projection, supported on pillars, from the back drawing-room. Fig. 344. shows the elevation; fig. 345. the section; and fig. 346, the ground plan of a plant cabinet of the simplest kind, attached to one of the houses in the Palace Gardens, Kensington. In fig. 346. a shows the entrance from the drawing-room, and b a flight of steps leading to the garden; c is a large camellia in the centre; and d d are shelves for pots. Very commonly a plant cabinet is formed on the flat roofs of some attached out-buildings, such as a back kitchen, washhouse, or rubbish place. In short, there is no situation where there is a door or a window in the house, and where perpendicular light is obtainable outside, in which a plant cabinet may not be formed. However irregular the plan may be in point of outline, and however uneven the roof or roofs which are to form the floor, the situation is still eligible for a plant cabinet, or a small greenhouse; on the same principle as an irregular piece of ground is for laying out a flower-garden in the picturesque manner.

In the plant cabinet, as in the flower-garden, the whole depends on the contrivances for displaying the flowers. The great art in arranging an irregular plant cabinet consists in the disposition of wires and rods, in the form of trelliswork, arches, and arcades, for climbers; and of imitations of rockwork, banks, or benches of stones, for receiving bushy or creeping plants in pots, such as pelargoniums, mesembry-anthemums, etc. The rockwork, banks, benches, etc, may be made of bricks and cement, stained or dashed with paint in such a manner as to represent different kinds of stone or spars; or natural crystallisations of different kinds may be procured. The smallest, the most irregular, and apparently the most unfitting situation for a plant cabinet may be rendered interesting by means of climbers on perpendicular props, no matter how irregularly placed, plants rising from groups of rockwork on the floor, and trailing plants suspended in pots or baskets from the ceiling. In some cases, the effect of a picturesque grove of climbers of this kind may be heightened by the introduction of a little stained glass in the roof; but this ought to be used most sparingly, and not in a larger portion in one place than a star a couple of inches in diameter, half a dozen of which will suffice for the roof of a plant cabinet containing upwards of 100 square feet of glass.

In the evenings, on particular occasions, two or three coloured lamps may be introduced; but these, also, should be used very sparingly. Whatever attracts more attention than the plants should be avoided, as interfering with the main object of the structure.

520. Wherever the plant cabinet is placed, and in whatever manner it may communicate with the house, one point only in its construction is absolute; which is, that it should be at least as lofty, from the floor to the glass of the roof, as the living-rooms of the house. When this is not the case, it has an appearance of meanness, which, instead of an elegant ornament, renders it rather a disagreeable excrescence. The form of the ground plan must, of course, be in a great measure determined by the situation; but, in general, a parallelogram, placed with its narrow end to the house, will have the best effect One side and the roof should, at all events, be glazed; but, if both aides be glazed, the effect is much better than if one is opaque; provided, however, that the roof is glazed, and the width of the house is as great as its height, or nearly so. Fig. 347. shows the ground plan, and fig. 348. the side elevation of a plant cabinet of this description; and fig, 349. shows the elevation of the end, with steps leading down to the garden. In fig, 347. there is a bed in the centre for planting camellias, and there are holes left in the wall at a for the admission of vines or other climbing plants, the roots of which are to be in a bed outside the house.

Plants will thrive in a house with all its sides opaque; it being understood that the house is as wide as the side walls are high, and that the plants are placed on a stage, or on the floor, so that the light may fall in direct lines on the upper surface of their leaves. The sides, when of glass, may be framed and glazed in any mode considered as in character with the windows of the house; and the roof may be glazed like a common span-roofed hothouse: but, if the panes of glass are above 8 in. wide, they ought to be of extra-thick crown glass, or of the thick rough glass, such as is now sold in London for conservatories; or of plate glass. One or more sashes in the side or sides, or one sash in the farther end, ought to be made to open at top and bottom, for the sake of ventilation; but this may be accomplished without having the sashes hung with cords and pulleys, by having two narrow sashes made to slide past each other, or even by having a pane in the upper and lower part of each window to open.

In general, all hinged sashes or panes should open outwards; because then they are not in the way of the plants within.