2 BULLETIN 8&4, IT. S. DEPARTMENT OF AGRICULTURE. 
The drawings illustrate the principles and the typical forms of con- 
struction. The three typical cross-sections of the kiln have been 
drawn to show some of the possible and allowable variations. Factors 
influencing such variables are indicated in the text. Thus the draw- 
ings may be altered to fit individual requirements and local condi- 
tions. 
THE KILN. 
The kiln proper consists of a drying chamber approximately 11 
feet high, 12 to 16 feet wide, and of indefinite length, usually from 
20 to 100 feet. The lumber is piled in the kiln lengthwise (with or 
without kiln trucks) and on either side of a central open space or 
passageway extending the length of the kiln. This central space, 
as well as the space between the piles and either side wall, is usually 
from H to 2 feet in width. 
Fig. 1.— Typical cross section of kiln with center-spray chamber. Studs and sheathing, crib construction, 
wood roof, wood spray chamber, wood posts. 
Between the floor of the drying chamber and the bottom of the 
kiln proper there is a space about 4 h feet high in which heating coils 
are situated to provide the necessary heat for the drying chamber. 
