might have remained at their stations several hours. Thus it is pos- 

 sible that initial efforts at damage control might have kept ships 

 operating, but it is clear that vessels within a mile of an atomic 

 bomb air burst would eventually become inoperative due to crew 

 casualties. 



SECTION II 



Observations on Test "B" 



The Board divided into two groups for the observation of Test 

 "B." Four members, after surveying the target array from the 

 air, witnessed the explosion from an airplane eight miles away at 

 an altitude of 7,500 feet. The other three members inspected the 

 target array from a small boat the day before the test and observed 

 the bomb's explosion from the deck of the USS HAVEN, 11 miles 

 at sea to the east of the burst. 



The Board reassembled on the HAVEN on July 26, and the 

 members have since examined photographs, data on radioactivity, 

 and reports of other phenomena, and have inspected some of the 

 target vessels. They have also consulted with members of the Task 

 Force technical staff. 



As scheduled, at 0835 Bikini time on July 25, a bomb was 

 detonated well below the surface of the lagoon. This bomb was 

 suspended from LSM-60, near the center of the target array. The 

 explosion was of predicted violence, and is estimated to have 

 been at least as destructive as 20,000 tons of TNT. 



To a degree which the Board finds remarkable, the visible phe- 

 nomena of explosion followed the predictions made by civilian and 

 service phenomenologists attached to Joint Task Force One. At 

 the moment of the explosion, a dome, which showed the light of 

 incandescent material within, rose upon the surface of the lagoon. 

 The blast was followed by an opaque cloud which rapidly enveloped 

 about half of the target array. The cloud vanished in about two 

 seconds to reveal, as predicted, a column of ascending water. From 

 some of the photographs it appears that this column lifted the 

 26,000-ton battleship ARKANSAS for a brief interval before the 

 vessel plunged to the bottom of the lagoon. Confirmation of this 

 occurrence must await the analysis of high-speed photographs 

 which are not yet available. 



The diameter of the column of water was about 2,200 feet, and 

 it rose to a height of about 5,500 feet. Spray rose to a much 

 greater height. The column contained roughly ten million tons of 



96 



