122 PERIOD OF VIBRATION OF STEAM VESSELS. 



the weight or displacement multipHed by the cube of the length and divided by the 

 moment of inertia of the midship section, or 



l-(^) (B) 



The coefficient, however, is seen to vary as the loading changes, since the bend- 

 ing moment curve alters with the loading, and the deflection curve also. If the 

 displacement be expressed in long tons ; the length to propeller post, in feet ; and /, 

 in feet: — 



For the vessel Plates 56 and 57, 



V. P. M. = 1 ,619,000 — ^_^ = 76, as observed 



s AX rj ' ' 



(9) 



