NIPHER OUTPUT OF THE NON-CONDENSING STEAM ENGINE. 



43: 



od. The line K^ represents ^ IIP as function of boiler pressures, 

 O/'and OP' bein<4" simultaneous values of mean effective and 

 boiler pressure, measured from the atmospheric line. V K rep- 

 resents the belt-power requii'ed to drive the engine if boiler and 

 mean effective pressure were zero. 



Calling // ^ the atmospheric pressure, and P' =z boiler pressure 

 measured from atmospheric pressure, we have 



h + A _ h -h^ 

 h + P\ - h +P' 

 or 



h -\- P 



(6) 



In this equation the value of P is known from (i). Po is de- 

 termined by means of the indicator. It remains to determine 

 P' Q-, the boiler pi-essure required to drive the engine at the fixed 

 speed represented in Fig. i , when tv = o. 



Fig. 1. 



If the engine were driven at a very slow speed, the cylinder 

 pressure would be identical with boiler pressure until the point 



