GLASS STRUCTURES 105 



of it have kindly consented to the use of it here. It is 

 called the "Model Forcing Pit." Fig. 40 shows a cross 

 section of this house, which is made with a valley in the 

 center, so that in point of fact it is two houses. The total 

 width of both houses is twenty-six feet. The alleys are 

 dug into the ground in each house eighteen inches wide 

 and eighteen inches deep and boarded up on each side. 

 The beds on each side are four feet wide, and the atten- 

 dant can cultivate them when standing in the alley. The 

 peak of the greenhouse is only four and a half feet above the 

 ground level or six feet from the bottom of the alleys. The 

 sides are only one foot above the ground, and are made 

 of plank nailed to cedar 

 posts and banked upon 

 the out side with horse 

 manure in winter. The 

 roof is covered with 

 moveable sashes 7 or 

 lYi feet long and of any 



convenientwidth. Com- Flg " 40 " Market gardener>s 

 mon hotbed sash (3x6feet) might be made to answer, but 

 sash having larger glass than is generally put in them is 

 best. Large sized glass is preferable, 12x16 inches being a 

 good size. A light framework for the sash to rest on, 

 similar in construction to that shown in figure of a green- 

 house hotbed is necessary, and the sashes should be 

 screwed down and ventilation secured in the same way as 

 there explained. At B, where the two roof sections meet, 

 the sashes rest on a plank 12 inches wide cut out ^by 8 

 inches, to form a gutter to carry off water, as shown in Fig. 

 41. The center planks rest on two rows of 2x3 inch posts, 

 two and a half feet long and twelve inches above the beds ; 

 these posts are four feet apart in each row. 



