576 



detonation energy with density of loading or to a difference in the partition 

 of a given amount of detonation energy between the shock wave and bubble 

 phenomena for the two types of charge. 



The values of the proportionality constant, Jj^, are higher here than for 

 the shots in free water. The values of K, (Table 3QV) are similarly higher 

 than the free water values. This wonld argue that there may well be a 

 systematic difference between the deep and shallow shots. (See Sec. 10.) 



In Table XVIII are shown for comparison some resiilts from an earlier 

 report^) on larger charges. The first charge was within 3 bubble radii 

 of the surface and is thus roughly comparable to the 25 gm charges at 5 ft. 

 The other two are relatively deeper. The values of J]_ are slightly higher 

 than for the l/2 lb charges in free water (Table XV), but this is within 

 the limits of error of Table XVIII and may not be significamt. 



TABLE XVIII 

 MAXIMUM BUBBLE RADIUS, LARGE TNT CHARGES 



* Calculated from period. 



C. Radii for Second and Third Periods in Free Water . These were 

 found as described above and are sumnarized in Table XIX. No values for the 

 very shallow shots were measured because of .the uncertainty in the depth 

 after the first oscillation. The scatter in J is an indication of the 

 decrease in precision of these values as compared to the first bubble cycle. 



One value for a 56 lb charge is included. The exterior of the bubble 

 appeared to be very rough during the second oscillation and the radius 

 cannot be estimated at all precisely. To calculate Jp in this case, the 

 bubble was assumed to migrate upwards 15 ft between trie first and second 

 bubble maxima. 



IV. COf/IPARISON OF F^ERII.ENTAL RESULTS WITH THEORY 



9. Resume of the Theory ; The Role of the Adiabatic Parameters 



The theory of the oscillating motion of the bubble of gases produced by 

 an underwater explosion has been developed in recent years principally by 

 Doringl^), Zollerl^), Hermesl^), Keil and Wunderlichl7 ) i^ Germany; Taylor^^^ 



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