575 



the photographs*. Since the bubble may very well be ovoid when so close 

 to the surface, the nearly vertical radii (i«rtiich were the only ones that 

 could be measured) may not accurately represent the radius of the 

 equivalent spherical volume. 



TABLE XVII 



FIRST MAXIMUM BUBBLE RADIUS FOR TSTRYL CHARGES 

 CLOSE TO THE SURFACE 



Charge Weight: 0.0558 lb 



It will be noted that the average value of J-, for loose tetryl is about 

 3.5^ above that for the pressed tetryl. The period constant for loose tetryl 

 was also foiind to be about this same percentage higher than that for pressed 

 tetryl, not only in free water (l/2 lb charges, Sec, 5) but also in this 

 same series of shallow shots (Sec. 7). Since both J-^ and K-|_ (the period 

 constant) are directly related to the energy of the bubble, the fact that 

 the difference between loose and pressed charges is inaintained here seens 

 significant, since equal systematic errors in the ir.easurement of J and K are 

 exceedingly unlikely. The results are most plausibly interpreted as 

 indicating a real difference in bubble energy, due either to variation of 



*■ See Ref. (l), Fig-.. 36-39. 



-39- 



