518 



5. S\arroundlng the fix)nt face of the gauge with a steel disc or 

 baffle increased the resulting damage by as much as 30%. 



6. In ordinary use with email charges, the time required for the 

 complete deformation of the diaphragm was about 3 times the time -constant* 

 of the primary shock-wave. Subsequent piolses from the bubble had no 

 appreciable effect on the final deformation \anle8s the experiment was set 

 up so that the bubble migrated toward the gauge during its oscillation. 



In this case, bubble pvilses increased the deformation as much as 8o^, 



and the time required for final deformation was correspondingly increased. 



7. It was proved by flash photographs that cavitation was formed in the 

 water in front of these diaphragms during deformation vinder certain con- 

 ditions but not for most of the experiments described herein. Although 

 exhaustive tests were not conducted, the theoretic£LLly derived criterion 

 for the formation of cavitation was found to agree with observations. 



8. If the mass of the diaphragm was increased by a factor of about 7*7 

 without a corresponding change in mechanical strength, the damage was 

 decreased by about 50^. 



9. Gauges placed in the Mach region of two intersecting shock-waves 

 from a pair of charges recorded up to 30% more damage than gauges placed 

 the same distance from a single charge of the same total weight. 



10. "Hie bubble from one charge was fovind to shield a damage gauge from 

 the effects of a second charge detonated on the other side of the first 

 charge, provided that the two charges were not too close. 



* The time required for the pressure to fsuLl to i/e, or S^'^^ ot its 

 maximum value. 



