565 



No data were obtained for loose tetryl charges in free water but a 

 few shots were made with 1/2 lb charges in water deep enough so that the 

 surface correction amoimted to only about 1%. These values are given in 

 Table VIII. It will be noted that the value of the period constant is 

 about 3% higher than for the pressed charges. Borden and Arons^) also 

 found a higher vsdue for loose tetryl charges of various sizes than the 

 value reported here for pressed tetryl. 



Because of the accuracy of the experimental methods and the con- 

 firmation of the results Tjnder differing conditions, it is felt that 

 this difference between loose and pressed tetryl is a real one. There 

 also may be a real discrepancy between the 1 oz and l/2 lb pressed 

 charges, eLLthough the evidence is not entirely conclusive. 



TABLE VIII 



FIRST PERIOD CONSTANTS FOR LOOSE TETRYL 



Charge Weight: 0.5'^'' lb 

 H = 39 ft 



* Depth not accurately known due to rough seas. 



Table IZ gives the results of several shots made with various 

 1/2 lb pentolite charges. These values were obtained incidentally to 

 other studies, and the experimental conditions are not strictly 

 comparable. The data are not siafficient in number to give a final 

 value for the period constant, nor is i't felt that thay are as accurate 

 as the scatter would indicate. The average falls between the averages 

 for the TNT and pressed tetryl charges of comparable weight. It may be 

 significant that the periods for the two long cylindrical cliarges sire 

 somewhat lower than for the other charges. 



Finally, for comparison, a number of period constants calculated 

 from period values available in the llteratiure are given in Table X. 



-9- 



