6 Walker, The Poly tropic Curve 



efficiency will approach a value somewhere in the neighbour- 



L 



hood of half that of the value of i — 



r8-i 



This exolains the 



approach of the efficiency to a value of 38 per cent, instead 

 of 65.2. 



•2 *4 <6 «S 1-0 l«E 1-4 



Values of n or r/io 



(recompression Raho) 



If, however, p has a value greater than unity (say 1.1), as 

 represented by the complete diagram of Fig. 4, then as n 

 approaches S, the effect of diminution of the shaded area in 

 reducing efficiency becomes negligible, since there always 

 remains the work done and the heat given represented by the 

 corresponding portions of the unshaded area, so that the limit 

 in this case is determined by the ratio of these portions. This 

 ratio is always given by (7) when p>i. 



These facts at once explain why efficiency generally does 

 diminish in internal combustion engines when " n " is inten- 

 tionally or otherwise reduced in value, but to the writer's 



