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 4’ x 6 stick 
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 
in cost between the two grades may be indicated by stat- 
