OF THE 



UNIVERSITY 



SCIENCE OF THRESHING. 25 



ance with the threshing members is the mechan- 

 ism which separates (hence the name "Separator") 

 the shelled grain from the straw in which it is 

 entangled. While the operation seems simple 

 enough on first thought, there are some things 

 involved which render the devising of a successful 

 separator very difficult, and as yet no one has con- 

 structed a machine which will remove every kernel 

 from the loose straw under all conditions of threshing. 

 Gravitation is the form of attraction which causes 

 unsupported bodies to fall. Owing to inertia, a 

 falling body starts to fall quite slowly, its motion 

 downward increasing in a fixed ratio as it continues 

 to fall. A body placed in a vacuum will fall 16 ft. 

 the first second, the first half of the second it falls 

 only four ft. while the last half of the second, owing 

 to its increased speed, it falls 12 ft. It requires one- 

 fourth of a second to fall the first foot. The sepa- 

 rating of the grain from the straw is done by gravity; 

 time must be given the kernels to fall out of the 

 straw. In falling they must pass down through the 

 small interstices between the stalks. 



If we pick up a quantity of straw between whose 

 stalks and leaves loose kernels of grain are entangled, 

 we may toss the bunch or bundle around up and down 

 a good deal without dislodging the grain. The 

 kernels will remain in the straw. We must move the 

 stalks of the bundles about among themselves in 

 order to shake the kernels out from their resting 

 places, and the more mildly and gently we do this, 



