SCIENCE OF THRESHING. 



-D is the third quarter of the revolution, the crank 

 being at the lowest point, and both inlet and outlet 

 ports being wide open. 



E shows the parts at the end of the revolution in 

 the same position as at the starting point. 



To compensate for the shortening of the valve 

 stem and the eccentric straps from the take up for 

 wear, as well as for taking up the crank and shaft 

 bearings, it is necessary to set the valve so that it will 

 have even throw or travel in relation to . the center 

 of the engine stroke. 



THE GOVERNOR. 



When an engine is running at a constant speed the 

 work done by the steam in the cylinder must just 



equal the resistance over- 

 come at the flywheel rim. 

 Should the resistance be- 

 come less than the work, the 

 excess power causes the 

 moving parts to move 

 faster and faster, and the 

 engine "races" or "runs 

 away." If, on the con- 

 trary, the resistance at the 

 flywheel rim is greater than 

 the work done in the cyl- 

 inder, the engine slows 

 down and finally stops. 

 The work required of an 

 engine does not, of course, 



