THE GREEN-HOUSE AND CONSERVATORY. 19 



called conservatories, and this signification of the word is 

 generally accepted. 



A Pit is a structure below the surface of the ground, 

 generally excavated six to eight feet, and covered with a 

 glass roof. From such a structure the frost is excluded 

 with little expense, and a great heat may be maintained. 

 It is usually a cheap building, used for propagation, grow- 

 ing roses, and forcing vegetables. 



The glass structure which will be in general request is 

 the green-house, which is adapted for the growth of most of 

 our flowering plants. The same structure may be con- 

 verted into a stove by merely increasing the power of the 

 heating apparatus. 



A green house may be 

 "span-roofed" (Fig. 1), 



or " lean-to " (Fig. 2), FlG . 2 . FIG. i. 



that is, with both sides 



of the roof of glass, or with a back wall of brick, stone, 

 or wood, the roof and front being glass. 



The former is better for the symmetrical and healthy 

 growth of the plants, but requires powerful furnaces to 

 maintain sufficient heat ; the latter is more economical, 

 both in structure and heating, and is sufficient to grow 

 most of our ordinary " green-house plants." 



