349 



to a spherical shape. The profiles for small values of "t/t^^ are of 

 questionable accuracy, since the treatment using two Bessel functions breaks 

 down for small values of the time. However, the convexity in these profiles 

 may not be entirely fictitious because of the nonuniform distribution of 

 water loading. 



In Table V the results of the treatment assuming a parabolic pro- 

 file (Part III) are compared with the results of the more exact treatment 

 with parameters appropriate to the UERL diaphragn. It is significant that 

 the values of z»^ are in close agreement except for small values of 6 , the 

 more exact treatment giving larger deflections than the parabolic. This 

 discrepancy is evidently due to the fact that the profile is more nearly- 

 conical than parabolic for waves of very short duration as mentioned above. 

 The values of "t^ for the more exact treatment are about 20^ lower than 

 those for the parabolic. A corresponding difference is found in the funda- 

 mental frequencies. 



36 



