GREENHOUSE CONSTRUCTION AND HEATING 



29 



wooden plates because 

 of their smaller size, 

 durability and efficiency 

 in preventing ice from 

 forming along the 



Fig. 15. Wooden gutter. eaVCS 



Gutters are expensive, difficult to keep in repair, and 

 being wider than eaves-plates they cast a larger shadow 

 upon the plants in the greenhouses. Wooden gutters, 

 similar to the one shown in Fig. 15, are in common use. 

 They must be kept well painted in order to prevent rapid 

 decay. Cast-iron gutters (Fig. 16) are more satisfactory 

 than wooden ones, and should be used more generally. 

 They are made in great variety, but drip grooves are 

 essential features. 



Sash bars for the roof, sides and ends vary greatly in 

 size and to some extent in shape. Fig. 17 shows typical 

 forms of roof and side bars. The sash bars should be 

 large enough to prevent sagging in any part of the house, 

 but no larger than necessary, because of their obstruction 

 to the light. Their size is largely dependent upon the 

 strength and rigidity of the supporting structure of posts, 

 purlins and braces. The 

 sizes shown in the illus- 

 trations are in gen- 

 eral use. 



Roof. The roof 

 should not be heavier 

 than necessary to se- 

 cure proper strength, 

 and it should be built 

 in such a manner that 

 there will be the least 

 obstruction to light and 

 sunshine. The pitch of 

 the roof should receive 



rrmcirlfratirm F 'S- l6 - Iron 8 utter wit h roof bars con- 



lUUdiUCiailUIl. nected. Also shows connection with iron post. 



