18 EXTRACTING AND CLEANING FOREST TREE SEED. 
over which wire screening is stretched to form a long oblong box. 
The frame is held rigid with four internal X-shaped cross braces 
about 5 feet apart, connected at the ends by horizontal slats or 
strips. The screening is stretched horizontally from end to end of 
the frame and should never be wound round the frame. The frame- 
work may, of course, be constructed to fit any width of screen. The 
ends of this long screened box or shaker are left open to allow the 
free passage of cones. Holes are bored through the center of the 
four cross braces before they are put in the frame, and when the 
whole box is assembled a2-inch iron pipe, bent at the upper end so asto 
form a crank, is thrust through these holes and firmly fastened to the 
frame, the lower end projecting beyond the shaker for a short dis- 
tance to form a support. This pipe is then set in two wooden frames 
so as to allow the shaker to revolve. The lower end of the churn 
should be mounted from 3 to 6 inches below the upper end, where 
the cones are inserted. A chute should be constructed at the upper 
end, so that cones dumped into the chute will roll directly into the 
shaker. When in operation the whole machine should be set on 
canvas sheets to catch the seed as it falls through the wire screens. 
One man is required to revolve the shaker, another to pour in the 
cones, and a third to remove the empty cones at the lower end. The 
total cost of this apparatus is about $5. It has a capacity of approxi- 
mately 40 bushels of yellow-pine cones per hour. With other species 
which give up their seed less readily a modification of this design is 
necessary to secure a more violent shaking of the cones.* 
SORTING CONES. 
Various appliances to separate opened from unopened cones 
have been deyised. These consist of slats so spaced as to permit the 
small, unopened cones to pass through while retaining the larger, 
opened cones, the principle being similar to that used in machines 
for grading fruit by size. Such devices generally give poor results 
on account of the irregular size of both opened and unopened cones. 
It is usually preferable to sort cones by hand. The small amount of 
seed, however, ordinarily obtained from cones which do not open in 
the first drying does not justify much expenditure for sorting. 
SEED CLEANING. 
IMPURITIES PRESENT. 
After extraction from the cones, the seed contains impurities which 
must be removed. Aside from wings, these consist mainly of broken 
cone scales and needles, broken and empty seeds, resin, and dust. 
1JTllustrations of this machine and of a box shaker are given in Plate IV of Forest 
Service Bulletin 98, ‘“‘ Reforestation on the National Forests.” 
