171 



The rise r.f the bubble - h , 



An important quantity concernea with the motion of the bubble is the rise at the end of the 

 first oscillation, since this determines the position of the bubble when the peak pressure in the wave 

 is omitted. None of the above methods of approximation enables this quantity to be estimated. 

 Inspection of the full calculations published for four depths, and of the unpublished calculations 

 for a 1 or. charge at 6 feet show that the rise h due to gravity is given by the following empirical 

 formula with an error not exceeding 10 per ctnt over the range of non-dimensional depths from 



Z„ = 2 to 2„ = ' 







h = 1.05 t« (non-dimensional) 



Using equation (l6) this becomes 

 1.19 



(non-dimensional) (12)- 



This rise of the bubble has been calculated on the assumption that all free or rigid surfaces 

 are remote enough to exert no disturbing effect on the motion. Its value fs plotted in Figure 8. 

 The correction for the proximity of a surface is dealt with in the Appendix. 



