36 THE CONSTRUCTION OF THE FORCING-HOUSE. 



erable to a few very large ones. The house shown in 

 Figs. 12 and 13, which is unusually light and fully exposed 

 to the sun, is ventilated by a continuous double row of 

 sash a foot wide, and this width is sufficient for all narrow 

 even-span houses. Uneven spans may require ventilators 

 a foot and a half in width, and I should think that two 

 feet would be the utmost desirable width for any ordinary 

 purpose. It is generally unnecessary to have side venti- 

 lators in forcing-houses whose side walls are under four 

 feet in height. In general, it is best to hang the ventilators 

 at the bottom, thereby allowing the heated air to pass 

 out at the very peak. If a row of sash is placed upon 

 either side, and each row is operated by a separate mech- 



Line B C to face outside 

 of house and Sash Bars 

 to nail to it 



Ideal Plate.made from a Vx 6'ttick 

 The inner edge at (A) dressed down to 1 inch thick 



19. A good forcing-house plate. 



anism, the most perfect means of ventilation will be 

 secured. In the very wide shed houses, ventilators upon 

 the sides may be necessary. 



The glass and glazing.-Glass for forcing-houses should 

 always be double-thick, not single-thick. The double-thick 

 glass may be expected to save its extra cost within a year 

 or two in the less breakage, and it makes better joints 

 and a> warmer house than the single-thick. The difference 

 m cost between the two grades may be indicated by stat- 



