20 BULLETIN 876, U. S. DEPARTMENT OF AGRICULTURE. 
of a series of inclined steps, arranged about 2 inches apart, over 
which the mixture is allowed to run. About three-fourths of the 
rye falls through the openings. The simplest method of all is to 
spread the seed on a barn floor and allow chickens to pick out the 
erain, which they will do, leaving the hairy vetch. Separation can 
also be accomplished on clover graders or wild-oats separators, 
which consist essentially of endless belts of felt or Canton flannel 
set at such an incline that the rye is carried up and over the top 
while the hairy vetch rolls to the bottom. 
Large lots of seed can not be handled in such a manner, however, 
but must be separated on a spiral separator. This simple but in- 
genious device is really the keystone of the hairy-vetch seed industry, 
as without it there would be no way to separate seed in large quanti- 
ties. The general type of construction of the spiral separator is 
shown in figure 6.' 
The spiral separator is operated entirely by gravity and centrifugal 
force and contains no moving parts. It consists of three or more 
concentric spiral chutes mounted on a vertical column, the outer 
chute being larger than the others and fitted with a vertical rim. 
The mixture of vetch and grain is fed into the hopper at the top of 
the machine, whence it is distributed equally to each of the small 
spirals. Upon opening a slide the mixture commences to whirl 
down through the spirals at a high rate of speed, a given portion 
traveling from top to bottom in a few seconds. The rye, oats, or 
other grains, being flat-sided or oblong and not rolling readily, cling - 
to the center of the spirals and are discharged from a central spout 
at the base. The hairy-vetch seeds, however, being round and 
smooth, roll quickly to the outsides of the spirals, where they jump 
over the edge and fall into the large outside spiral. At the base of 
the large spiral is a vertical partition which divides the stream of 
hairy vetch into two parts, with the heavy and more nearly round 
seeds on the outside and the light, irregular or shrunken and broken 
seeds on theinside. Thus, there is discharged at the bottom of the 
machine three grades of seed---the grain, the second-grade hairy 
vetch, and the first-grade hairy vetch. If cockle or other semiround 
seeds are present, they come out for the most part in the second- 
grade seed. 
Oats are separated more easily than rye, and rye more easily than 
wheat. Rosen rye is somewhat more difficult to separate than 
common rye on account of its plumper and more nearly round kernels. 
4 Spiral separators are put on the market by at least four manufacturers in this country and sell for $35 
to $85, depending upon their construction and finish. The cheaper machines made of galvanized iron 
work quite as well as the more expensive ones, which are of heavy sheet iron and castings. The former 
are popular with farmers, while the latter are preferred by millers. The machines are also useful for remoy- 
ing mustard and other round seedsfrom grain. There are norestrictions in the way of patents orroyalties 
on the manufacture of spiral separators, but owing to their peculiar design they can hardly be made eco- 
nomically at home. 
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