STEAM ENGINES 389 



engine. The indicator diagram shows more clearly the 

 effect of throttling the steam of an engine than any de- 

 scription. Fig. 273 shows a diagram taken from an 

 engine ; No. i, with full load ; No. 2, with about half load ; 

 No. 3, with about quarter load. 



In all the diagrams it will be noticed that the 

 points of compression, admission, cut-off, and release 

 remain constant, while the steam and expansion lines 

 vary. 



537. Automatic cut-off governor. Steam cannot be 

 used as economically under low pressure as under high, 





FIG. 274 



