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HEATING GREENHOUSES. 



Amoxgst the various methods of heating gi'eeuhouses. hot water is 

 certainly the most economical, efficient, and certain ; but under ordinan' 

 circumstances, so Httle artificial heat is required for greenhouses, strictly 

 so called, that we think the erection supei-fluous, unless where it can be 

 put up at the same expense as the common flue. There are circumstances, 

 however, where its apphcation can be made to them with advantage, 

 namely, when several houses are to be heated at the same time, and 

 attached together so that one boiler may sen'e the purpose of several, or 

 where the greenhouse is so placed that the back, or one of the ends, may 

 be connected with the walls of the kitchen, or with some part of the 

 dwelling house, where a constant fii'c is kept up. In this case, a boiler may 

 be so constructed as to be heated by the fii'e used for domestic pm*poses, 

 by means of a pipe communicating thi'ough the wall, with the pipes in the 

 greenhouse. A small greenhouse might be heated by this means from 

 any ordinary kitchen, or even parlour fire ; a cock, upon Kewley's prin- 

 ciple, being placed so as to tmii the hot water ofl* or on, at pleasure. 



For ti'opical plants, where a considerable temperatui-e is reqiiii-ed. a hot 

 water apparatus should be fitted up expressly for the pm*pose, unless the 

 stove be of ven- limited dimensions, and placed so as to be heated as 

 above ; but we shall have occasion to retm'n to this subject when we come 

 to treat of plant stoves. 



The degree of heat requu'ed for gi'eenhouses is just sufficient to repel 

 fi'ost and to dispel damp. To efiect the former, if the vrinter be mild, the 

 fire may not be requisite more than from thi'ee to twelve nights in the 

 course of the winter, and the degree of heat need not be more than 

 sufficient to warm the flue. ^'Mien required for drying up superfluous 

 damp, if the house be properly glazed and cai'e taken not to spill water 

 unnecessarily, one or two fires during the season may be sufficient. 

 These, let it be obseiTed. should be apphed dming the day. when the 

 house can be fully ventilated, for the escape of the damp air. It is to be 

 observed, that when required for dispelling frost, the best. and. perhaps, the 

 most simple rule is, not to apply the fire until the fi'ost appear to be foiTuing 

 on the inner siurface of the roof Hghts. excepting in the geranium house, 

 where it should be apphed when the frost is forming on the outer smtace 

 of the glass. The application of heat mil be more fully explained under 

 each division, as no general nfie can be safely acted upon. 



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