536 



to compare explosives at constant charge-to-gauge distances rather than 

 at constant weights or volumes, so the equivalent weights of explosives 

 were the quantities determined directly. "Hie other ratios can easily 

 be calcxilated if one ratio, the exponents m and n, and the explosive 

 densities are known. 



For example, If the equivalent weight ratio Wy^/Wg (D and d held 

 constant) is designated as Wj)^; the equivalent volume ratio V^/Vg 

 (D and d held constant) as Vjj^; the equivalent distance ratios 

 d^d. (D and W held constant; and cLo/d^ (D and V held constant) as 

 djjjj and djjy, respectively; and the density ratio W^Wg (V held constant) 

 as Wy, then 



'Dd 



(%)-^e 



(23) 



^ - ("v) -'X"^ 



Vn/u ^"'/" 



(2k) 



and 



^ 



e4) 



m/n 



(25) 



2. The Effect of Wooden Frames 



In tests with damage gaiiges, some sort of framework for fixing the 

 orientation of gauges and charge-to-gavige distances is essential. The 

 first type of frame used at UERL consisted of a wooden cross at the center 

 of which the charge was fastened. One gauge was mounted on the end of 

 each of the four eurms of the cross so that it faced the charge. The 

 whole rig was lowered by a rope or wire cable into the water with safety 

 lines connected to the gauges. A top view sketch of this type of frame 

 is shown in Figure 10. 



Gauges 



Charge 



Figiire 10. First frame type 



