Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 2, 1802).djvu/527

495&#93; nor unable to with .1 or variable climate. Th. don of h it h< i in general, differs little from that .EBN-HOI . of both is to rec< ive as mnch benefit as possible from the genial warmth of the sun, assisted by the heat artificially procured from sub- terraneous stoves and flues. — We shall, the re tore, at present, only give an analysis (from the 1st. vol. of the second scries of Recreations in Agriculture, &C.) of the princi- ple on which Dr. Anderson's im- proved hot-houses are constructed, and for which he has lately obtain- ed a patent. He first points out the defects in the present method of erecting hot-houses ; in consequence of which the heat of the sun is not employed with that advantage of which it is susceptible. In the pre- vailing mode of building these houses, the roof glasses are, with very few exceptions, laid into the frames, by folding one frame over the other, and thus leaving an open space between each pane ; through which the air has a free passage, while the front panes are closely covered round with putty. This communication with the open air at the upper part of the house, is their chief imperfection ; for the power of the morning sun is thus lost for several hours ; and, in the evening, when the warm air with- in begins to cool and to contract in bulk, the cold air from iinl/'ioiu rushes in through the top or roof- glasses, cools the whole house in the most expeditious manner, and thus counteracts the influence of the solar rays. To remedy these inconveniencies, die patentee proposes the following HOT [495 plan of o 1, for, hoi desig, or guch plants as 1 niiar I em ise is to be built of the usual dimensions, but with ;i i!v tut ; and, as it. iedj all tha - or junfl - eeu each ire to be carefully closed with putty. Over this flat be erected, and covered either with slate, or likewise with glass, which will better answer the purpose. The upper chamber, which will thus serve as a reservoir for the heated air, communicates with the com- mon atmosphere only at its lower part, that is immediately over the roof of the lower house ; and there is a contrivance for another occa- sional communication with the lat- ter, by means of a pipe. or tube, that extends from the top cf the up- per chamber, almost to tie ground below. By this construction, as soon as the. sun expands the air in the lower house or chamber, a part of that air rises through the tube into the upper chamber ; where, it ascends to the top or roof, forcing out the copier air contained in the upper chamber, which passes oft" through the openings left above the floor of this chamber, or in the roof of the lower room. During the whole of this heating process, the vines, which are trained along, beneath the glass roof of the lower chamber, are surrounded with heated air. In the evening, when the influence of the sun is withdrawn, the. warm air begins to cool, and consequently to con- tract its bulk ; thus the external air rushes in, through the.aperture im- mediately over the lower glass roof, into the upper chamber, This cold air
 * . another sloping roof is, to