shock wave was perceived at the Japanese fishing boat as two loud reports like rifle shots, arriving 7 or 8 minutes after the flash was seen. At Rongerik the shock wave shook the windows in the buildings 11 minutes after the first blast was observed (Reference 68). The cloud formed was like a funnel with the narrowing at about 25,000 feet (19 km) altitude. The growth of the cloud is shown in Figure 58. As early as 10 minutes after burst, the cloud was already more than 65 miles (106 km) across. At about H+30 minutes, aircraft from the cloud photogra- phy project visually observed material falling from the cloud from the point at which the funnel flared out (Reference 26). At Station 70 on Eneu, radiation readings began to rise within one-half hour of the burst and at 1 hour reached 250 R/hr (see Figure 59). The personnel within the bunker were well sheltered; during the fallout peak the reading within the structure was 0.035 R/hr (Reference 16, p. K-~3). The fallout picture at Bikini at this time is summarized in Figure 59. At 0800, the fleet began to receive fallout, which resembled pinheadsized white and gritty snow. The USS Bairoko and the USS Philip were pre- Paring for the reentry sequence to Bikini. A helicopter had been Launched from the Bairoko for radiological reconnaissance, but was recalled when the CTG 7.1 informed the Bairoko that the Eneman complex was radiologically too hot for reoccupation. The source of information for CTG 7.1 may have been the Station 70 bunker on Eneu. Plans for the launch of four other helicopters, including one to aid the USS Molala in controlling the YAGs lying west of Bikini, were also cancelled (Reference 80). The radiation levels aboard the ships built up quickly, from 0.0002 to 1 R/hr on the Bairoko in 5 minutes. At this time the Bairoko was 31 nmi (57 km) at 133° from the Bikini ground zero. Washdown systems were started on all affected ships, and CTG 7.3 ordered the vessels south to 50 nmi km) from Bikini at "best speed" (Reference 80). 210 (93