Greenhouses, their construction and equipment . placed on the north end,where it will not shade the house. Theprincipal disadvantage is that during themiddle of the day, when the suns rays aremost potent, they strike obliquely againstthe roof and much heat and light is lost byreflection. Moreover, a large part is cut offby the sash bars and rafters. In the east and west arrangement, the di-rect sunlight enters from the south side only,and in the morning and afternoon strikes theroof obliquely. During the middle of theday, when it is most efl^ective, it strikes al-most at right angles, although
Greenhouses, their construction and equipment . placed on the north end,where it will not shade the house. Theprincipal disadvantage is that during themiddle of the day, when the suns rays aremost potent, they strike obliquely againstthe roof and much heat and light is lost byreflection. Moreover, a large part is cut offby the sash bars and rafters. In the east and west arrangement, the di-rect sunlight enters from the south side only,and in the morning and afternoon strikes theroof obliquely. During the middle of theday, when it is most efl^ective, it strikes al-most at right angles, although it is not even-ly distributed and the plants on the northside of the house receive much less thanthose on the south side. This would seem tobe a serious fault, but in practice is lessserious than in theorv. Of no s^rowerswhom the author consulted on this point,38 were in favor of the north and south ar-rangement, 42 were in favor of the east andwest and 30 expressed the opinion that thereis little or no difference. GREENHOUSE ARCHITECTURE 53. 54 GREENHOUSES Uneven Span Houses.—The uneven dis-tribution of light in even-span housesrunning east and west early led to theexperiment of cutting off the north one-fourth, so as to make an uneven or three-quarter span house. The following advant-ages are claimed for these houses: (i) Theysecure a more even distribution of direct sun-light to all plants. (2) The north span ad-mits indirect light which insures better re-sults than may be secured from a lean-tohouse. (3) The heat is more evenly distri-buted than in a lean-to house. They areoften used in growing roses and other plantsrequiring a maximum of light. The con-struction of uneven span houses has beenvaried from time to time, the general ten-dency being to lower the north wall to ap-proximately the height of the south arrangement insures even better distri-bution of light and does away with the neces-sity of elevated benches. Uneven span houses are sometimes usedfor gr
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