32 DEPARTMENT BULLETIN 1425, U. S. DEPT. OF AGRICULTURE 
and-better, and with Douglas fir and western larch for 1 by 8 inches 
and wider No. 1 common-and-better, and 2 by 8 inches and wider 
select common-and-better; with at least the standard and better 
grades of redwood 8 inches and wider; and with at least the select 
grades of other species. 
It is not uncommon to find special crossers used only at the rear 
of the pile or at the rear and center. ‘The idea back of such methods 
is that the rear and center crossers are subject to greater deprecia- 
tion than the front crosser. This theory does not, however, appear 
tenable upon review of the underlying causes of crosser depreciation, 
nor is it substantiated by the results of actual yard comparisons. 
What little variation in degrade occurs in the different tiers of 
crossers runs slightly higher in the front crossers and lower in the 
rear and center crossers. 
DIMENSIONS OF THE CROSSER 
The dimensions of the crosser have a very direct bearing upon 
seasoning. The influence of the width has been brought out forcibly 
in the preceding discussion. Special crossers should not exceed 6 
inches in width, and 4 inches is preferable. Width of the stock 
crosser is usually fixed by that of the stock piled. When random. 
width lumber is self-crossed, the use of the 4 and 6 inch widths for 
the crossers should be definitely insisted upon, since much deprecia- 
tion can thus be avoided. 
Thickness of crossers is a very important item in seasoning prac- 
tice. The necessity for adequate horizontal circulation in the lumber 
pile, and more particularly within the lower third to remove the 
moist air which drops into this section from above, has been em- 
phasized. Obviously, this horizontal air movement is assisted by 
any increase in the thickness of crossers. Further, this means of 
increasing circulation in the pile is a very flexible one, since the 
crosser thickness can be increased in the lower section or wherever 
a more positive air movement is desirable, by the simple expedient 
of doubling the crossers at such points. And if an even greater 
opening is desired at intervals, three or more crossers can be em- 
ployed in the same manner. 
Crosser thickness, where seasoned crossers are used, may be the 
key to the solution of serious drying difficulties. Horizontal circula- 
tion in the pile may be increased by this means wherever it is most 
needed. ‘The usual lag in drying between the upper and lower parts 
of the pile can thus be greatly reduced. Stain development, most 
severe in the lower sections, can be greatly retarded by doubling 
crossers in this part of the pile, without inviting the increased de- 
preciation that would result from an equally rapid drying in the 
upper sections. All of these definite advantages have been thor- 
oughly tested by numerous comparisons in the different regions. 
In an attempt to cut down the time required for drying redwood 
the relative merits of various crosser thicknesses were studied. It 
was found that stock piled on 4/4 (1-inch) crossers required 36 per 
cent more time, and stock on 6/4 crossers 10 per cent more time to 
become air-dry than did that on 8/4 crossers. For the California 
pines, an increase in the crosser thickness not only increased the rate 

