STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 63 



This results from a very general desire to give the structure a 

 finer effect from a front view ; but it must be regarded as a 

 decided sacrifice of utility and adaptation to purpose. Making 

 the front of graperies from eight to ten or twelve feet high, 

 is not less objectionable than to make the roof on a level with 

 the plane of the horizon. The sides of a hot-house should never 

 be more than four or five feet in height. This gives the struc- 

 ture a more characteristic appearance, and is certainly mucli 

 more fitted for the purpose in view, than upright sashes, which 

 make the roof appear to the eye only a fraction of its real extent, 

 whether viewed from the interior or the exterior of the structure, 

 apart from the consideration, that the upright part of the house 

 neither produces nor ripens the berries of grapes so well as the 

 sloping part of the transparent surface. All structures of glass, 

 for horticultural purposes, should have a parapet wall, from 12 

 to 20 inches in height, on which to rest the frame-work of the 

 fabric ; then about four feet of upright glass. This modification 

 gives the house, whether of large or small dimensions, a neat 

 and characteristic appearance. A span-roofed house, 24 feet 

 wide and 16 feet high, with a five-feet front, makes a well- 

 proportioned house, and gives about 16 feet of a run for the 

 vines*under the rafters, — the slope of the roof being upon an 

 angle of 45°, which, as we have already said, is the best pitch 

 for a hot-house roof for general purposes. 



Until these few years, the forms of hot-houses were generally 

 plain, flat, right-lined buildings, differing in no respect from one 

 another than in their size and relative des^rees of clumsiness. 

 Lately, however, a great improvement has taken place in the 

 form and construction of this class of buildings. Single-roofed 

 houses are fast dwindling into desuetude, and right-lined houses 

 are giving way to the more light and elegant curvilinear roofs. 

 This is an important step in the right way; and we regard 

 those who, laying aside their prejudices in favor of right-lined 

 houses, adopt the curvilinear shape, as conferring a benefit on 

 exotic horticulture as acceptable to those interested in the pro- 

 fession as it is creditable to themselves. 



Regarding curved houses, Loudon says, — "On making a 



few trials, to ascertain the variety of forms which might be 

 6=^ 



