THE AIR SEASONING OF WESTERN SOFTWOOD LUMBER 19 
pile reached an average moisture content of 23 per cent in 128 days, 
whereas that is the lower pile required 191 days, or a period half 
again as long, to come down to 23 per cent. 
Increase in the foundation height is justified up to the point where 
the loss of yard space and additional cost of piling may offset the 
very real seasoning advantages mentioned. The minimum clearance 
below the stringers upon which the stock rests should be 12 inches. 
This means ordinarily a foundation height of 18 inches at the rear, 
and proportionately more at the front if the usual slope is built into 
the structure. When the influence of an active horizontal circulation 
under the pile is correlated with the local seasoning problem, a 
greater clearance may be found profitable. In yards where the rate 
of drying is exceptionally slow, an 18-inch rear clearance may be the 
most effective and cheapest remedy, returning real dividends on the 
added cost. Further, this potent aid to fast drying can never be the 
cause of depreciation from excessive drying, since it affects primarily 
only the lower section of the pile. 
In practice to-day the average rear height of foundations is be- 
tween 8 and 12 inches, which at best means a clearance under the 
pile of about 6 inches. Practice varies, however, from a 4-inch 
height—simply stringers laid on the ground—to 24 inches, or a 
rear clearance of 18 inches. Plate 5, A shows an only too common 
type of foundation. With such construction, wind currents along 
the alleys exert but little effect upon the circulation under the pile. 
It is not difficult to appreciate how damp and sluggish the air must 
be in the lower portion of these piles and beneath them. 
SLOPE OF FOUNDATION 
The slope in the foundation from front to rear is many times 
given more thought than other more essential considerations. A 
slope of from 0.5 to 1 inch per foot of length is commonly used. 
This, if carried up in part at least with the pile, undoubtedly makes 
it easier to give adequate pitch to the roof and consequently to se- 
eure good run-off. Also, water leaking into the pile will drain off 
more rapidly. With the piles adequately roofed, however, slope be- 
comes of minor importance, except as it may be of some little 
mechanical assistance in constructing the pile. If slope is not built 
into the foundations, it may be obtained by using extra crossers 
at the front and center, as illustrated in Plate 3, A. 
DIRECTION OF FOUNDATIONS 
Almost without exception in the West, lumber is piled perpen- 
dicularly to the alleys, and foundations are constructed accordingly. 
Piling parallel to the alleys has sometimes been considered to be a 
superior means of seasoning, but this claim was not substantiated 
when actual comparisons of the two methods were made. Two very 
apparent objections to parallel piling are, (1) that the run-off 
from the roof falls in the narrow spacing between piles, where the 
soil necessarily dries out more slowly than in the wider rear alleys; 
and (2) that the cost of handling stock by this method is greater than 
by perpendicular piling. 
