GREEN-HOUSE AND CONSERVATORY, 



985 



SO as to admit of the sash shding down its whole length over 

 the one immediately below it ; and admitting that every alter- 

 nate top sash be thus let down, and the next bottom sash to 

 it, let down its whole length, resting by its top rail upon the 

 front of the house, where the front does not exceed four or 

 five feet in height, and the bottom rail on the ground ; by this 

 means, the half of the entire roof surface will be, with little 

 trouble, and at a comparatively trifling expense, exposed to 

 the rain, dew, air, &c. When the front is of greater height, as 

 is most generally the case with conservatories, then, instead 

 of letting down the bottom sash to the ground, they may be 

 drawn up under the top sash immediately above it, by similar 

 means to that by which the top ones are let down. When 

 ventilation is not to be given to its fullest extent, then the 

 sashes may be let down to any given degree in the same 

 manner, and having them (as a security against accidents by 

 slipping down) secured by spring catches fixed to the side rail 

 of the sash, and corresponding notches in the side of the 

 rafters. Conservatories are in general loftier than any other 

 species of hot-house, excepting those which are intended for 

 the cultivation of palms, or similar tropical plants, which require 

 much room. They, therefore, of themselves present very ample 

 means of ventilation, as all the sides and ends, that are made 

 of glass, may be so contrived as to be either removed or air 

 admitted by half their surface, by opening the sashes in such 

 a way as those that are fully open may cover those that remain 

 shut ; and, in addition to this, such parts of their sides as are 

 opaque, when it does not break in on any other arrangement, 

 may be ventilated either by glass windows or by wooden ven- 

 tilators, upon the principle of those already recommended, 

 and so placed as to suit existing circumstances. Ornamental 

 brass ventilators, having an expanding orifice upon the outside, 

 may be introduced into the walls when building, and may be 

 opened or shut at pleasure ; and probably they may be less 

 objectionable in their appearance than those constructed of 

 wood, as recommended for the culinary hot-houses. 



The plants which most generally enter into the conservatory, 

 are such as are capable of withstanding a considerable degree 

 of cold, being for the most part natives of the Cape, New- 



6k 



