2186. The principle on which a cold house can be constructed in a warm climate must either be that of the exclusion of the heat by coverings or envelopes; or the abduction of heat by evaporation or contact with cold bodies. Heat will be, to a certain extent, excluded, by forming the house in the ground; by excluding the sun's rays from its roof; by a high wall on throe sides, leaving only an opening in the middle of the north side; and by a double or treble roof of glass to the excavation. A house to be cooled by evaporation may also be sunk in the ground; or it may be raised above it, shaded from the sun, and over it may be supported a number of shower pipes (2176.), which, by producing a gentle and continual rain on the glass roof and stone or other sides of the house, would draw off much heat by evaporation. Enclosing it by a line of powerful jets d'eau would effect the same purpose. To produce cold by abduction, the house might be sunk; its floor supported on pillars; and its sides and bottom kept in contact with a running stream; or, if it could be afforded, ice renewable as it melted. These hints are sufficient to show how cold plant-habitations may be formed in any climate: to enter more at length on the subject would be useless, in a work calculated chiefly for the climate of Britain. In our Encyclopï¾µdia of Cottage, Farm, and Villa Architecture and Furniture, will be found various designs for ice-houses and cool dairies, as well as illustrations of the general principles on which all houses, whether for economical purposes or plants, intended to retain an atmosphere cooler than that in which they are placed, require to be constructed.
