THE AIR SEASONING OF WESTERN SOFTWOOD LUMBER vs 
horizontal circulation in the lower part of the pile. Tramways also 
prevent the direct sunlight from reaching the lower part of the pile. 
Naturally, the rate of drying below the tram level is greatly 
affected. Actual yard tests under ordinary conditions have shown 
that stock below the tramway requires 40 per cent more time to dry 
down to a given moisture content than stock above the tramway. 
Also, during a given period, stock below the tramway will reach a 
moisture content of only 18 per cent while the stock higher up is 
coming down to a moisture content of 11 per cent. It follows that, 
in drying pine, stain development is much greater below the tram. 
Such differences between the upper and lower part of the pile are 
very much greater than in piles of the same height where trams are 
not used. 
Trams are going into disuse gradually but surely. A considerable 
number of tram yards are still found in the California pine region, 
but only an occasional one is found in the Douglas fir region; there 
are few in the Inland Empire and in the redwood region. Where 
trams are in use, their effect on drying should be definitely recognized 
and circulation below the tramway assisted as far as possible by 
modifying the arrangement of the lower part of the pile. 
PILE FOUNDATIONS 
The foundation upon which the pile is erected should be so con- 
structed as to perform several very definite functions, the least of 
which are the designation of the location of the pile and the keeping 
of stock from direct contact with the soil, for almost any kind of 
bottom will do these things. Horizontal algnment of the lumber, to 
prevent deformation and even breakage in the lower part of the pile, 
depends largely upon the foundation. Construction must therefore 
be such as to prevent appreciable sag at any point. To provide ade- 
quate bearing surface for the stock, a stringer must be placed across 
the width of the foundation for each tier of crossers to be used in 
piling. But the function of vital importance to seasoning, and the 
one generally disregarded, is the facilitating of proper circulation. 
Adequate clearance between the ground and the foundation string- 
ers is necessary for both horizontal and vertical circulation. It is 
absolutely necessary for positive horizontal circulation at or near 
the bottom of the pile, by which means the moist air dropping to the 
bottom of the pile is removed. Not only does such construction 
provide for the flow of moist air from beneath the pile, but also it 
affords access to wind currents from the main and rear alleys. These 
currents find little if any ingress at the front and back of the pile 
because of the crossers, 
TYPES OF FOUNDATION AND STRUCTURE 
Plates 3 and 4, illustrating the standard types of the better foun- 
dations now used in the West, show the basis for recommendations. 
The construction shown in Plate 3, A is an example of the unit pier 
and stringer bottom. Plate 3, B shows the common pier and stringer 
foundation of the continuous type. Both of these are excellent if the 
ground is properly prepared and heavy mud sills are used. The 
109391°—28——-3 
