STEAM ENGINES 



363 



from the steam chest A, through the steam port C, into 

 the front end of the cylinder D, and press against the 

 piston E. This forces the piston through the cylinder 

 toward the end F. At the same time the steam which 



FIG. 243 CYLINDER AND VALVE OF STEAM ENGINE 



has been previously admitted to the end of the cylinder F 

 is forced out through the cylinder port G into the ex- 

 haust chamber H, and out through the exhaust port / 

 into the air. By the time the piston E has reached the 

 end of the stroke the valve B has reversed its position 

 so that the steam chest A is connected with the end of 

 the cylinder F by way of the steam port G. The exhaust 

 port / is now connected with the exhaust end of the 

 cylinder C, hence as the steam enters the cylinder at the 

 end F it drives the piston toward the end D. 



