DREER'S VEGETABLES UNDER GLASS. 29 
As there are two rows of sashes on each side of the 
house there must be five lines of support, the peak or ridge 
piece serving for two lines of sashes. These five lines are 
permanent. The outer lines, forming the sides of the house, 
are of wood, resting upon wood, with glass below. The 
interior ones rest upon iron pipe posts, which are strong and 
yet light, occupying but little room. 
Each of the two hundred (or more) sashes required to 
cover one of Mr. Esher’s houses is 7 feet long by 3% feet 
wide, glazed with 10 x 12 panes. 
Each sash when on the house is held in place by two 
screw bolts. These bolts pass through the sash, take hold 
of the wood beneath easily, have square heads and can be 
removed with little trouble. 
Provision is made for ventilation by making every third 
sash of the upper row, on each side of the house, movable at 
its lower end. This admits fresh air immediately over the 
walks on both sides of the house. 
The joints of the sashes are covered with weather strips 
to keep out the cold, and along the peak of the entire roof 
where the sashes come together there is nailed a strip of felt 
or tarred paper, which effectually turns the rain and snow. 
The paper is tacked in place with circular tin roofing buttons. 
THE VENTILATORS. Sometimes the sash to be used for 
a ventilator is simply hinged to the opposite sash, at the 
upper end. This permits the lower end of the sash to be 
raised at pleasure. Mr. Esher has what he thinks is a better 
plan. He takes two pieces of hoop iron, each a foot in 
length. In each piece five holes are drilled. Through the 
middle of each piece a six-inch wood bolt is passed, and 
driven part way into the top of the ridge piece of the green- 
house. 
In summer time, when the houses are not in use, these 
bits of hoop iron still remain in pairs (a sash’s width apart) 
