74 THE PRINCIPLES OF FLORICULTURE 



used for forms may later be used for bottoms of wooden 

 benches. 



61. Side- wall construction. The foundations usually 

 come to the level of the interior grade of the house, and 

 from here the side-walls begin. They may be of cement, 

 wood, hollow-tile, concrete blocks, brick or stone. Pref- 

 erence is now given to cement because of its durability, 

 and the expense is not much greater than for wood. In 

 the end it is cheaper. There are various forms of side- 

 walls, as follows : 



Concrete capped with iron sill, to ivhich flat rafters are 

 attached. In the first type of construction, the concrete 

 side-walls extend from eighteen inches to three feet above 

 the foundations, depending upon whether solid beds or 

 raised benches are used in the interior (Fig. 12, upper). 

 In large houses, the side- walls are usually ten inches thick. 

 On these side-walls, nine-inch iron sills are held firmly in 

 place by a fine mixture of one part cement to two parts 

 sand (Fig. 12, middle). Flat-iron rafters are attached 

 to this sill by iron lugs and bolts, and the upright sash- 

 bars are held in place by the same means (Fig. 12, 

 lower). No side-walls should ever be high enough to 

 shade the first bench in the interior of the house. 



Concrete capped with iron sill, ivith flat-iron posts extend- 

 ing to the eaves. In the second type of side-wall, the 

 construction is practically the same as in the first, the 

 main difference being that a flat-iron post is used which 

 goes only to the eaves, in place of the flat-rafter which 

 extends to. the ridge. 



Wooden posts embedded in foundations, to which posts, 

 wooden side-walls are attached. In the third type of con- 

 struction, wooden posts of six-by-six inch material and 

 eight or nine feet in length are strongly embedded in the 



