346 



Figure iu shov/s how the periods calculated iTom the 

 equation (2.1) compare with the observea results. The 

 agreement is excellent. 



Using k = .23 and i'ormulas (1.27) and (1.28) the mi- 

 gration v/as fo-und by numerical integration of I^ I'or each 

 value Z . The calculatea results are compared v/ith the 

 observed values in Figure 11. The agreement seems to be 

 fair. 



The peak pressure is calculatea from formulas (1.56) 

 and (1.50). ir we use the values of k and y determined 

 by the period measurements, the calculated pressures are 

 about one-half the observea pressure. Theoretically, it 

 would be possible to use one experimentally determined 

 value of pressure with the tv/o constants a and p to solve 

 for the three quantities rQ, k and y. This was done but 

 it did not lead to consistent results. It seems likely 

 that the value of y at the time of minimum size may be 

 different from the value of y during the time of expan- 

 sion and contraction. 



Despite this difficulty with the magnitude of the 

 pressure, the variation of pressure with depth is given 

 approximately by formula (1.50). If we multiply the cal- 

 culated pressures by a constant chosen so that the calcu- 

 lated pressure agrees with that experimentally observed 

 at the depth of 18.5 feet, vie get Figvu?e 12. 



