i8 



THE CONSTRUCTION OF THE FORCING-HOUSE. 



roof with an even span, those with a lean-to or true shed 

 roof, and those with an 

 uneven or broken roof. 

 These various types of 

 houses are illustrated in 

 the accompanying dia- 

 grams. Figs, i and 2 

 show the ordinary types 

 of an even-span house, 



pj gs 3 &nd 4 (page J9 ) 



A simple two-walk even-span house, 



aojeet wide. 



forms of an uneven or 



broken span, and Figs. 5, 6 and 7 (pages 20, 21 and 22), of 

 a lean-to or shed house. The older type of forcing-house 

 was rather narrow in proportion to its width ; that is, it 

 was rarely more than 20 feet wide, whilst the length might 

 vary from 50 to 300 feet. A house of this width is propor- 

 tionately more difficult to heat and to manage than one of 

 greater width, and the tendency at the present time is to- 

 wards much wider houses, especially in establishments 

 where a large product is expected to be grown. The wide 

 house, however, when built with a gable roof, becomes too 



j. A broken or uneven span, 20 feet wide, on a side kill. 



high to admit of economical construction and heating, and 

 the plants are also too far removed from the glass for 

 best results. It is necessary, therefore, in these very 



