SCIENCE OF THRESHING. 67 



the others so that it can be enlarged and used when 

 the belt stretches and is cut and relaced. 



Good lace leather of uniform width of about five- 

 sixteenths of an inch should be used, with the ends 

 tapered for convenience. The smooth side should be 

 placed out, as the lace will then last longer. 



Pulleys are crowned or larger in the center to 

 cause the belt to run in the center of the pulley. If 

 the shafts of two pulleys are parallel, the belt has a 

 tendency to run to the large part of the pulleys. If 

 the shafts of two pulleys are nearer together at one 

 end, the belt when doing work or is tight, has a ten- 

 dency to run towards the ends nearest together. If 

 one shaft is level and the other high at one end, the 

 belt has a tendency to run towards the low end. 

 If a belt slips, it will run off on the side of the pulleys 

 nearest together. 



