346 FORCING GARDEN. 
The roof is unequally ridged, the north or shortor side:be 
ing slated and furnished with ventilators, to admit air, 
The sashes are immovable,'and the laps of the panes are 
closely puttied. There is a path within, and a single turn 
Fig. 42. 
of a flue behind. We should prefer the following form, 
in which there are ventilators, a a, and a hot-water appa- 
ratus surrounding the whole pit. The dimensions of this 
Fig. 43. 
may be fifty feet long, and nine feet wide, the glass being two 
feet and a half from the curb of the bark pit in front, and 
five feet behind. We next present a section of a pine-pit 
with a curvilinear roof, in which the astragals are parallel. 
A segment of an elliptical arch somewhat less than a quad- 
tant, the origin of the curve being on the front wall, seems 
better adapted for a pit than any portion ofa circle, This 
