154 SCIENCE OF SUCCESSFUL THRESHING. 



placed in the second notch and third or fourth hole. Some- 

 times these two sieves are used together and when so used, 

 the former, G, should be placed in the first notch and third 

 hole and the latter, H, in the fifth or sixth notch and the 

 fifth hole. 



For a screen, either the one-fourteenth by one-half inch 

 oblong hole, L, or the one-sixteenth by three-eighths inch, 

 K, is suitable, depending upon the size of the kernels of 

 wheat. For cockle, the five-thirty-seconds inch round hole 

 screen, I, is the right size. 



Turkey Wheat. Some varieties of wheat, such as the 

 "Turkey," which is raised extensively in Oklahoma, is very 

 difficult to knock out of the heads and often six rows of con- 

 cave teeth will not thresh it clean from the straw. In this 

 case, one or more three-row concaves of corrugated teeth are 

 necessary. For such grain, the cylinder speed should be kept 

 fully up to the stated number of revolutions. 



Threshing Rye. Rye is more easily knocked out of the 

 heads than wheat, and usually two rows of concave teeth 

 are sufficient. When damp, the straw is tough and as it is 

 long, it tends to wrap on the cylinder and beater. To pre- 

 vent this, the cylinder should be run at a high speed say 

 800 for the twenty-bar or 1150 for the twelve-bar. Tough 

 rye straw is more liable to wrap if bruised by the cylinder, 

 and therefore, in threshing damp rye, it is best to use not 

 more than two rows of concave teeth and often these may 

 be left quite low, as the high cylinder speed suggested above 



