BOMBS AT BIKINI 



made excellent records of the line of demarcation be- 

 tween agitated water and water not yet swept. The 

 shock wave buffeted every ship of the target array and, 

 still traveling at velocity greater than that of sound, 

 continued its outward sweep. 



After traveling three miles, the shock wave had lost 

 much of its original character. Its hammer-blow qual- 

 ity was less pronounced, and it took on the character 

 of a sudden violent gust of wind. The automatically- 

 operated motion picture cameras on Bikini showed the 

 palm trees shake vigorously as the invisible wave shot 

 past. 



After roughly fifty seconds the wave reached the 

 support ships, located ten or more miles from the 

 Zeropoint. But at this distance it was no longer a shock 

 wave; it was a mere pressure wave. The wave front 

 was no longer ^'square"; the velocity had subsided to 

 that of sound, 1140 feet per second. This fully-tamed 

 wave produced in the ears of observers only a dull, 

 low-pitched thud. 



The shock wave had quitted the lagoon; but thou- 

 sands of instruments bore witness to its passage, and 

 five ships were sinking. 



PRESSURE 



Within five seconds an excellent, indelible record 

 was obtained of peak pressure, the most important 

 property of the shock wave. The majority of the gages 



