THE GREEN-HOUSE. 



17 



modern culture of plants. The idea of darkening a 

 house at the ends or from above, for the sake of eco- 

 nomising fuel, is therefore quite out of the question ; 

 but some varieties of form have a tendency to Avaste 

 heat, without producing a counterbalancing benefit 

 by light; such as where the upper part of the roof is 

 exposed to the north, and where there are glazed 

 porches of entrance from that quarter. Large win- 

 dows to the north ought also to be guarded against; 

 and the entrance -door of a green-house ought never 

 to be on the north side, unless protected by a close 

 porch or other ante-inclosure. 



The form of a green-house must be such as to 

 admit of ventilation, by the entrance and exit of air. 

 In a conservatory, we have already stated it as an 

 essential point, that the roof should be removable in 

 summer. It is also a great advantage to that descrip- 

 tion of winter garden, to have the sashes of the side 

 or sides and ends removable ; thereby leaving the 

 plants, in effect, in the open air, and subject to all 

 the weather of the season. For a winter garden of 

 pots it is not essential that the roof be removable, 

 because the removal of the pots to the open air effects 

 the same purpose : but it is of great consequence that 

 there should be a power of opening the roof, as well 

 as the south side and ends, to admit air to enter, cir- 

 culate, and escape, every mild day during the winter 

 months. The common mode of effecting this in 

 right-lined houses, is by having the i*oof and front 

 composed of sashes which slide in grooves, and let 



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