258 WORK OF STEAM AT EFFLUX. 



therefore, from (2) of Art. 136 and (1) of the present Art,, 

 we have 



W 



which gives the velocity of efflux, ft being the coefficient 

 of efflux (Art. 131). 



COE. 2. From (1) of Art. 130, we have 



D = ^J2 (.,-.,). (0) 



Let F! and F 8 be the volumes of steam per second from 

 a cubic foot of water at P l and P 2 pressures respectively ; 

 then (Art. 130), 



QV 1 = a^v lt 



which in (6) gives 



and we see again, as in (3), that the work of steam varies 

 as the cube of the water evaporated. 



V 

 Solving (7) for Q -* = ^, we have 



$ n 



which gives the theoretical velocity of efflux, 



