THE AIR SEASONING OF WESTERN SOFTWOOD LUMBER 29 
construction productive not only of slower but of more uniform dry- 
ing. These include narrower spacing between boards, thinner stick- 
ers, and other methods to be discussed later. 
FLAT-PILED AND EDGE-PILED STOCK 
With but rare exception, all stock is flat piled. In an occasional 
yard 2 by 4 dimension is edge piled with the purpose of reducing the 
likelihood of bowed stock, a material objection in this item. Inas- 
much as both methods afford exactly the same bearing, top and bottom, 
it is doubtful if there is any advantage in edge piling. Further, 
the necessity for greater precision in piling to secure proper verti- 
cal circulation in the pile makes edge piling certainly less desirable 
than flat piling. 
NUMBER OF CROSSERS TO THE COURSE 
The most effective spacing of crossers between courses of stock, 
depends upon several considerations. Crossers should be frequent 
enough to avoid sag; otherwise bowed lumber and other types of 
deformation will result, as well as interference with horizontal air 
circulation. On the other hand, as the tiers of crossers are increased 
in number, air movement in the lumber pile meets more resistance. 
In actual yard tests to compare the relative efficiency of 3, 4, and 5 
crosser piles of 16-foot pine stock, little difference was found in the 
amount of degrade and but slight variation in drying rate and final 
moisture content. Less blue stain developed in the pile having three 
tiers of crossers and depreciation from cupping was smallest in the 
five-crosser pile. Within limits the crossers do not materially affect 
horizontal circulation since this is primarily a movement from one 
side of the pile to the other rather than from end to end; but, on the 
other hand, in seasoning pine stock the greater the number of crossers 
used the greater is the liability of crosser stain or blue stain develop- 
ment on that part of the lumber in contact with the crosser. These 
defects very generally result in the degrade of select and shop grades 
and to a smaller extent of the better common grades, but in any case 
they injure the appearance of the stock. 
The use of three crossers on stock 12 to 16 feet in length and of four 
or five crossers on longer stock is the most common practice, although 
a great deal of lumber is piled on two crossers with 4 feet or more 
overhang at the rear of the pile and very often an excessive number 
of crossers are employed. Everything considered, maximum efficiency 
can ordinarily be expected from the use of two tiers of crossers on 
8-foot and shorter stock, of three tiers on 10 to 16 foot stock, and of 
four tiers on 18-foot and longer stock. With a span of 8 feet or less, 
the lumber will not sag, and on the other hand with each additional 
tier of crossers in the pile circulation is further obstructed and, in 
piles of pine, the liability to crosser stain is increased. 
In the discussion of pile foundations, it was stated that each tier of 
crossers should bear directly upon a stringer, and for that reason the 
crosser practice should determine this feature of foundation con- 
struction. Unfortunately in too many instances “the tail wags the 
dog,” so to speak, and crosser practice is shaped to fit the foundations. 
While a tier of crossers, unsupported by a stringer, keeps the boards 
