REQUIREMENTS OF A FORCING-HOUSE. Ly 
are only high enough to allow of room for the plants to be 
grown under the glass, or, in the case of shed-houses, to 
give a proper slope to the roof. It is a common practice to 
secure head room in the forcing-house by sinking the walks 
below the ground level. In this way, the house is kept low, 
thus saving in cost of construction and;in exposure to winds. 
Such sunken walks are shown in Figs. 1 and 3 (pages 17 and 
18). Itis always handier, however, to have the main walks 
on a level with the surface, thus avoiding steps in passing to 
and from the establishment. In wet or springy ground it is 
I. A simple even-span, 10 feet wide. 
important to avoid sinking the house. The roof of the 
forcing-house should be as flat as is consistent with the 
ready shedding of rain and snow, in order that all the 
plants may grow close under the roof; for it should be 
said that plants are usually more stocky and productive 
and healthy when grown near the glass. The house should 
be of the lightest possible construction in order to gain 
sunlight, particularly if tomatoes, melons, cauliflowers and 
other sun-loving plants are to be grown. 
There are three general types or shapes of houses in 
common use for the forcing of vegetables. These are: The 
