88 SCIENCE OF SUCCESSFUL, THRESHING 



for, say, the threshing motion and turn the engine in the 

 direction in which it would run, just past the crank-end 

 dead-center. Block the cross-head so that the crank-shaft 

 cannot revolve, disconnect the cylinder-cock rod, and open 

 the throttle. This will admit steam on the crank-end of the 

 high pressure cylinder, and if the cylinder-cock on the 

 head-end of the low-pressure cylinder blows steam when 

 opened, it can come only from leakage of the metallic 

 packing in the center-head. 



