402 SUGGESTIONS ON 



morning light, whether that aspect should be treated on the 

 transparent light-admitting or the opaque heat-retaining principle, 

 and this may be further subject to a consideration of other 

 special objects ; but it will never, I believe, be disputed that the 

 northern aspect may be treated on the principle of preserving 

 internal heat, rather than of straining to catch a few extra rays 

 of dim diffusive light. According to this view the north side of a 

 plant house should always be a wall, and, when circumstances 

 permit, the eastern side may be a similar construction, either 

 wholly or in part ; but the south and the west would invariably 

 have a large proportion of glazing. 



It now remains to consider the roof. Taking the general 

 average angle of the sun's rays throughout the year, together 

 with the necessary conditions for throwing off rain, and general 

 convenience, the ordinary pitch of forty-five degrees appears very 

 suitable ; but instead of carrying the ridge of such a roof along 

 the centre of the parallelogram from north to south, I propose 

 to divide the length into a number of bays or compartments, such 

 as proportion or other considerations may dictate. These 

 divisions would then be covered each by its own ridge-roof 

 running east and west, with gutters between in the same direc- 

 tion. With regard to the two sloping sides of each ridge-roof, I 

 propose to make that to the south of glass, that to the north of 

 a cellular construction, which may be lined on the interior with 

 common boarding, plain or painted, or may be plastered or 

 covered with porcelain tiles, or, should a higher effect be yet 

 desired, it may be lined with silvered glass ; while externally any 

 of the ordinary covering materials of a mineral non-conducting 

 character, such as slates and tiles, may be employed. 



If a slight diagram be constructed it will be at once apparent 

 that, when the rays of light come from the south and do not form 

 with the horizon a greater angle than forty-five degrees, no particle 

 of light is obstructed by a roof made upon this principle, while, 

 on the other hand, a clear half of the radiating heat-wasting 

 surface will be replaced by the non-conducting reflector. 



The plan is equally applicable to cases in which the longer 

 line of the parallelogram may run east and west, but it would 

 not then be necessary to divide the length into compartments, 

 as the ordinary span roof, transparent on the south and opaque 

 towards the north, would effect the same purpose. 



Although the advocacy of a simple, natural, and economic 

 principle is my chief object, the method of c 



