Where the soil is wet, and does not admit of underground drainage, the icehouse may be constructed above the natural surface, and afterwards surrounded and covered with a mound of earth; it being farther protected from the heat by trees or shrubs, or what is perhaps preferable to either, by a covering of giant ivy. The common form of outdoor ice-houses is an inverted cone, and the supposed advantage of this form is, that as part of the ice thaws, the remainder slides down the sides of the cone, and still keeps in one compact body. This is no doubt true; but the advantage by no means compensates for the difficulty of constructing an icehouse in the conical form. A plain square room, with double side walla, say a foot apart, a double arch over, and a double floor under, which can be built with the same ease as any common cellar, will, all other circumstances being alike favourable, keep the ice as long as any conical form whatever. Where there is a doubt of being able to exclude the heat, treble walls, root; and floor may be resorted to; and the entrance, which should always be three or four yards in length, instead of being straight, may be made crooked, with a door at each turn.

The space between at least two of the doors should always be filled with straw; and, to render the removal of this straw easy, when there was occasion to pass from the outer door to the ice, it might be put into two or more canvass bags, like immense cushions, which might be hooked to the ceiling and the sides, so as to close up every interstice. The space between the second and third doors may be widened, and fitted up with shelves for holding articles which require to be kept cool, but not to the same degree as if they were placed in the ice-house. Fig. 219. is a section, and fig. 220. a ground plan, of an ice-house on the inverted cone principle, but of an improved construction. This form, as usually employed in English country seats, frequently fails in keeping the ice, from not having double walls and double or treble doors, or from imperfect drainage; but the plan now submitted is free from these defects, and will keep ice throughout the year in any climate, if covered with a sufficient thickness of earth or straw.

In this design, a is the well or cellar for the ice; b, a drain from its bottom, for carrying off such water as may be produced by the gradual thawing of the ice; c, a trap in this drain to prevent the external air from communicating with that of the ice-house; and d, a leaden pipe from this trap, connected with a small pump at e. The object of this pump is to allow of making use, during the heat of summer, of the very cold water produced by the thawing of the ice, either for cooling wines or water; and in order that there may always be a considerable quantity of the water produced by the melted ice in the trap, it may be made of considerable size, so as to serve as a reservoir or well. This water would be very nearly as cold as the ice, and might be used for all the same purposes; while it would have the great advantage of being obtainable immediately, whenever it was wanted, and with very little trouble. There are five doors to this ice-house, at f, g, h, i, and k; and a vacuity (l), one foot wide, between the two walls surroundiog the cellar, and covering the inner division of the passage (m). This passage may be fitted up with shelves, as a place for keeping vegetables and various other articles of food (raw or cooked) fresh during summer.

The cone containing the ice being supposed to be under ground, the natural level of the surface is shown at n n; and the whole superstructure may be covered in Britain, to the depth of 2 or 3 feet with earth, planted with ivy and surrounded with trees. In warmer climates the depth of earth ought to be increased to 8 or 10 feet. The sine of the well ought also to be enlarged, and there might be even a third vacuity round it The space between the doors i and k should be filled up by a barley-straw cushion, and it would be well to have similar cushions against the doors g and h, at least during summer. The two recesses, o and pt are here shown only 2 ft. in depth; but, by making the walls behind them of brick, that depth may be increased at pleasure. It may also be observed, that, in situations where brick is cheaper than stone, all the walls in this design may be built hollow; and that the side walls of the ice-well need not be more than the width of a brick in thickness, the one wall being tied into the other. It may be further observed, that, if it should be inconvenient to cover the building with earth, a covering of straw or reeds, or even planting ivy against the outside walls, and surrounding the whole with a few trees; will be equally efficient in keeping out the heat.

If trees cannot be planted, on account of the soil, or of shutting out any view, a slight roof elevated on props of any sort will have the same effect One of the most effective icehouses that we have ever seen, was sheltered in this manner by a wire trellis, covered with Ayrshire roses, honeysuckles, clematis, and Virginian creeper. Ice-houses may be built square just as well as round; and are at lees expense, as effective above the surface as under it A square ice-house above ground, or sunk 3 ft into it, may have treble hollow floors formed of bricks on edge, covered with foot-tiles or flagstones; and its side walls may be treble also, and built of bricks on edge. To form the roof, a 9-inch semicircular arch may be first thrown on these walls, and over this arch three vacuities built of bricks on edge and tiles: there may be five doors, as in fig. 220.; and the whole may be covered with a cone of earth or thatch 4 ft. thick, and clothed with giant ivy. In fact, by the use of framework, or a stratum of loose stones to keep the ice from the ground and to allow the water produced by its thawing to drain away from it, and abundance of thatch, ice may be kept above ground just as easily as potatoes.

Ice-houses are, however, in the present day, of comparatively little importance, from the number of freezing machines, refrigerators, and other machines for making and keeping ice, which have been lately invented.