TEST B: UNDERWATER EXPLOSION 



BASE SURGE 



The base surge was an awesome yet deceptive phe- 

 nomenon. It looked like a great wave of water. Ac- 

 tually it was a rolling mass of flufty spray, mist, and 

 air. It was not formed by the explosion proper, but 

 as an indirect after-effect. The millions of tons of 

 water thundering l)ack into the lagoon created an enor- 

 mous volume of spray and mist, which billowed out- 

 ward from the column base. The outward velocity of 

 this diffuse mass was initially more than fifty miles 

 per hour ; later it slowed to twenty-five miles per hour. 

 As the base surge spread out, it resembled a steadily 

 expanding and fattening doughnut. At first, its height 

 was about 300 ft. — a mere three times the height of a 

 battleship's mast; later it reached 1000 ft., and ulti- 

 mately towered to 2000 ft. 



The base surge, for all its tenuousness, left a kiss 

 of death on the majority of the target vessels. The white 

 billows carried radioactive fission products equivalent 

 to many tons of radium. Gamma radiation issued in all 

 directions. The base surge did not merely pass hy the 

 ships; its radioactive mist settled on the deck, moist- 

 ened every bit of exposed metal, wood, and canvas. 

 Even after the moisture evaporated, radioactive resi- 

 dues remained. And always the deadly gamma radia- 

 tion continued; persons remaining within its reach 

 Avould have been doomed. The radius of action is es- 

 pecially great downwind, since the surge tends to drift 



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