362 



FARM MOTORS 



ferent designs for carrying out the actions. The prin- 

 ciple is that of a cylinder separated into two parts by a 

 piston. There is a valve connected with the cylinder by 



FIG. 242 NEWCOMEN'S ENGINE 



means of which the steam is thrown from one side to the 

 other. This valve also conducts the exhaust steam out 

 of the cylinder. In Fig. 243, A is a steam chamber which 

 receives the steam from the boiler. B is the valve which 

 slides back and forth on the valve seat /. The valve B, 

 situated as it is in this figure, allows the steam to pass 



