SCIENCE OF THRESHING. 21 



their front and their rear edges. The proper posi- 

 tioning of these has given rise to much discussion, as 

 some experts claim that a cylinder is less liable to 

 slug when the front edge of the concave is the 

 higher, than when the concave is fixed in the opposite 

 position, as the wedge shaped opening through which 

 the straw passes broadens as the straw progresses and 

 does not tend to clog or bunch it. 



THE GRATE. 



A grate formed of slightly separated parallel bars 

 through which the kernels may easily fall is placed 

 just back of the cylinder. It should be so adjusted 

 that the straw in passing from the concave will 

 strike it at an angle ; this will aid the separation by 

 affording a comparatively straight or unobstructed 

 path for the -flying kernels which are thereby less 

 impeded and fall through more readily. This 

 position also allows the passing straw to sweep the 

 grate cleanly, and to prevent it loading up with chaff 

 and sticks. 



