BOMBS AT BIKINI 



and explosion-produced damage were to be fully under- 

 stood. 



Impulse can be computed directly from pressure- 

 versus-time data.* It can also be measured by special 

 gages which take account of intensity as well as dur- 

 ation of pressure. A number of such gages were con- 

 structed and placed at strategic locations on target ves- 

 sels. No detailed description of these gages is neces- 

 sary; many of them resemble some of the pressure 

 gages described on the previous pages, but contain 

 heavier, slower-moving pistons, better suited to taking 

 a long view of things. 



SHOCK- WAVE VELOCITY 



Shock-wave is the name given to a pressure wave 

 in its early, spectacular phase. To appreciate the spec- 

 tacular phase, one must recall the relatively unspectac- 

 ular behavior of most pressure waves. A typical pres- 

 sure wave, such as the sound wave produced by banging 

 a dishpan, leads a very dull life. It has no choice as to 

 the velocity of spreading. It always spreads at exactly 

 the same rate of roughly 1100 feet per second. This ap- 

 plies to faint sounds and moderately loud sounds, to 

 low-pitched sounds and high-pitched sounds. And such 



* It is well known that at moderate and great distances from 

 an explosion, the overall impulse zV zero. That is, the initial push 

 is exactly balanced by the pull of the ensuing suction phase. Close 

 to the Zeropoint, however, the push always exceeds the pull, and 

 the overall impulse has a net value greater than zero. 



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