144 



WAVE IMPACT ON 



this point in the pipe never exceeding 24 v. The diagram as 

 recorded by the indicator will, however, in general show 

 smaller maximum pressures than those actually obtained at this 

 point, because of the extremely short interval of time during 

 which these pressures are exerted. A close approximation 



24 v. 



Fio. 5 



to the effect of the suddenly applied force on the indicator 

 may be got by assuming it to be uniform over the time 

 41 4- V p seconds. Let F be the magnitude of the force on the 



piston in Ibs. ; let be the effective mass of the indicator 



u 



piston line and linkage, and let ' S ' be the stiffness of the 



