GREENHOUSE CONSTRUCTION AND HEATING 15 



to find single houses covering an acre or more of land, 

 and there are a few ranges (Fig. 1) that cover from 4 

 to 10 acres of land. 



Houses vary greatly in width. The majority of the 

 oldest houses range from 9 to 12 feet wide. The even, 

 connected ridge and furrow type, so common in the West, 

 varies from 15 to 18 feet wide. Numerous commercial 

 houses are from 20 to 24 feet wide. The 27-foot standard 

 house of the West has many advocates, and its width is 

 considered by some of the experienced growers the 

 maximum for best results. 



In New York, New Jersey and Pennsylvania 30 to 34- 

 foot houses are common, while Boston inclines toward 

 the 40-foot three-quarter span. (Fig. 2.) Much wider 



Fig. 2. Typical three-quarter-span houses of the Boston district. 



houses than these have been built and used for vegetable 

 forcing. There is, at New Castle, Pa., a hillside three- 

 quarter-span house (Fig. 3) that is 120 feet wide; and a 

 house of similar form, built on level ground, at North 

 Wales, Pa., that measures 172 feet in width. These are 

 very unusual structures. 



Wide houses should be considered with special refer- 

 ence to economy of heating. Jn actual practice the air in 

 a wide house with greater height cannot be changed as 

 often in a given period as that in two or more narrow 



