EXTRACTING AND CLEANING FOREST TREE SEED. 17 



CYLINDRICAL SHAKERS. 



A convenient size for the cylindrical shaker is 3 feet in diameter 

 by 4 feet long. The ends are of wood, but the sides consist of heavy 

 wire screening, usually with J-inch mesh, supported by a wooden 

 framework, and a hinged door. An axle is put through the center 

 of the cylinder, a handle attached, and the entire machine set on a 

 sawhorse or windlass. 



Of these types of shakers, the box is more easily constructed, and 

 is more effective with cones from which the seeds are extracted with 

 difficulty, since the shaking is more violent. On the other hand, 

 this is a disadvantage in the case of easily extracted seed, since it 

 breaks up the cones and increases the amount of rubbish to be removed. 

 Small cones, furthermore, like those of lodgepole pine, are apt to 

 collect in the corners of box shakers. 



Shakers of both types should be revolved at a rate which will just 

 bring the cones to the top of the mass and then allow them to fall 

 straight to the bottom. The speed necessary varies with different 

 species, as does also the number of revolutions required to extract all 

 of the seed. From 20 to 40 revolutions is ordinarily sufficient to get 

 practically all of the good seed. Too much time should not be spent 

 in trying to secure every seed, since those at the extremities of the 

 cones, which are extracted with the most difficulty, are often imper- 

 fect, and their presence in good seed lowers the quality of the whole. 



BARREL SHAKERS. 



A barrel may be used for seed extracting in practically the same 

 way as the devices already described. One and a half inch iron pipe, 

 with a crank at one end, is run through the center of the barrel. 

 With this as an axis the barrel is mounted on a box about 4 feet long, 

 2J feet wide ? and 3 feet high. Both ends of the barrel are screened, 

 with one screen movable to permit filling and emptying. For con- 

 venience in handling the seeds a tray may be fitted into the box to 

 catch them as they fall from the barrel. The large box is useful 

 not only as a means of support but also to keep the seed from blow- 

 mg away. A 40-gallon barrel, filled about two-thirds full, will hold 

 from 2J to 3 bushels of well-opened Douglas fir cones. Seed can 

 ordinarily be extracted thoroughly by revolving the barrel about 

 five minutes. 



INCLINED SHAKERS. 



Where seed extraction is to be conducted on a more extensive scale 

 a shaker capable of handling a larger quantity of cones should be 

 built. This is hardly worth while for less than 250 bushels of cones. 

 A model which has been used successfully with yellow-pine cones 

 consists of a wooden frame 3 feet square at the ends and 16 feet long ; 



