44 



SCIENCE OF THRESHING. 



the space between the concave and cylinder bars, thus 

 leaving about two inches through which the bundle 

 must be passed. This compressing process of the 

 teeth consumes a large amount of power. A five 

 hundred pound cylinder has a momentum or striking 

 force of thirteen hundred and twenty tons. This 

 indicates the terrible strain on the machine when a 

 bundle is fed in of sufficient size to stop the cylinder, 

 although this does not often happen. But the power 

 consumed when the bundles are not properly divided 

 up is enormous, and is still further increased when 

 the straw is damp and tough, as tough and pliable 

 straw clings more firmly to the cylinder teeth than 

 does dry and brittle straw. 



SELF-FEEDERS. 



Self-feeders are of comparatively recent develop- 

 ment, though they have been experimented with for 

 several years. After patient study and many unsuc- 

 cessful trials, the feeder and band cutter has reached 



