CHAPTER VI 

 FRAMEWORK METHODS OF ERECTING 



The two cardinal virtues of a good green- 

 house framework are these : It must be strong 

 and light, and it must cast but little shade. 

 The greatest advance in greenhouse con- 

 struction in the last quarter of a century has 

 been in the framework. The old houses with 

 their high, solid walls and heavy woodwork 

 are dingy and dark, when compared with the 

 modern house, 90 per cent, of which is glass, 

 with little or no solid wall above ground. The 

 framework of these houses casts but a frac- 

 tion of the shadow produced by the old-style 

 frame, yet it is so perfectly rigid against 

 storms and snow that the large panes of glass 

 are seldom broken or even loosened in their 

 setting. 



Three general classes of framework are 

 used: (i) Wood frame, in which all members, 

 including the posts, are of wood; (2) semi- 

 iron frame, in which the posts, purlins and 

 purlin posts are of pipe or structural iron, 



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