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pressure values measured just behind ships were defi- 

 nitely lower than pressures at the near sides of the 

 ships. Ordinarily, the pressure values were not as great 

 close to the surface of the water as they were at greater 

 depth. 



As the underwater shock wave struck the target 

 ships, it delivered terrific blows. A peak pressure of, 

 say, 1000 pounds per square inch produces a total force 

 of nearly a million tons on the underwater hull of a 

 large warship situated broadside. 



The underwater shock wave spread not only out- 

 ward but also upward. In fact, it was the upward 

 sweep which produced the most unprecedented effect. 

 The upward sweep of the shock wave and fireball ' ' gas 

 bubble ' ' reached the surface of the lagoon within a few 

 hundredths of a second. As the gas bubble approached 

 the surface, it produced a swelling called the dome. 

 The dome was, of course, illuminated from within ; and 

 atop the dome rode the LSM-60. The dome now burst, 

 and the fireball and water column leaped upward from 

 the lagoon. 



At about this instant, LSM-60 was blown to bits 

 and sprayed upward with the column. If the column 

 could be called a jet, LSM-60 's departure was about 

 the ultimate in jet assisted take-offs. If LSM-60 ever 

 sank, it was as a fine rain of steel fragments and dust. 

 No large fragment of her was ever found. 



Observers could scarcely follow the lightning ascent 

 of the column. Its upward rise was initially at a rate 



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