400 



2 3 4 5 6 7 8 

 Distance from Woll Z In feet 



Figure 9 - Upward and Horizontal 



Components of Displacement of 



the Gas Globe from 3A Ounce 



of-Tetryl or TNT 



The charge is assumed to be detonated 10 feet below 

 the surface of the water, far above the bottom, and 

 Z feet from a rigid vertical wall. The curves show 

 the displacement from the point of detonation up to 

 the point of greatest recompression, according to 

 approximate calculations. 



2 4 6 8 10 12 14 16 18 20 

 Height above Bottom in feet 



Figure 10 - Displacement of the Center 



of the Gas Globe from 3A Ounce of 



Tetryl or TNT, up to the Instant 



of Maximum Recompression 



Detonation is assumed to occur at the height shown 

 above a rigid horizontal bottom in water 20 feet 

 deep. Positive ordinates represent a rise, negative 

 ones a descent. The curve is based on approximate 

 calcxiLations. 



The effects due to gravity and to the surface are almost additive 

 but not entirely so, because of the occurrence of B or IS^I in F. When grav- 

 ity and the surface produce opposite effects, as in the case of a rigid bot- 

 tom or a free surface, the net displacement is a little greater than the 

 numerical difference of the values that the two displacements would have if 

 they occurred singly. In such cases the gas globe contracts to a smaller 

 radius than it would if only one effect occurred, and this decrease in the 

 minimum radius increases the displacement. Otherwise, as in the case of a 

 rigid wall located to one side of the globe or the rigid bottom of a boat 

 above it, the two displacements are slightly decreased by their coexistence. 



The formulas are illustrated in Figures 9 and 10, which refer to a 

 jA-cxjnce charge of tetryl or TNT detonated at Z feet from a surface. In 

 Figure 9 the surface is assumed to be a rigid vertical wall, the charge is 

 detonated 10 feet below the surface of the water, and the bottom is assumed 

 to lie much deeper. The vertical rise of the center of the gas globe and its 

 horizontal displacement toward the wall, up to the point of maximum compres- 

 sion, are shown by curves. In Figure 10 curves are shown for the same charge 

 Z feet above a horizontal rigid bottom in water 20 feet deep. It will be 

 noted that the gas globe descends if formed less than about 5.5 feet from 

 either the bottom or the free surface. 



The formulas for a free surface and for a rigid bottom are plotted 

 in general terms in Figures 11 and 12, as explained under the figures. 



