rise slowly. A peak intensity of 2.5 mr/hr was reached at 2130 hours, and then subsided. 5,4 3 July 1958 Fallout On 3 July 1958, following an event at Bikini Atoll, the background at Site Nan began to rise after a rainshower at 1500 hours, The background rose from 4mr/hr at 1500 hours to 12 mr/hr at 1645 hours, and then began to decline, as follows: 0300 hours July4...... 1200 hours July4... 1000 hours July5.. 5.5 . . 5 mr/hr ... . 3mr/hr tons 1 mr/hr 13 July 1958 Fallout On 13 July 1958 a slight rise in the background and the continuous air monitor was noticed at 0030 hours at Eniwetok Atoll. The background monitor reached a high of 1.8 mr/hr and the air monitor showed 20, 000 c/m at 0345 hours and then declined to 1.5 mr/hr and 2000 c/m at 0630 hours, 5.6 18 July 1958 Fallout At 1420 hours, 18 July 1958, the background monitor at the Site Elmer Rad-Safe Center began to rise sharply. At 1430 hours the background had risen to 20 mr/hr and reached a peak intensity of 34 mr/hr at 1449 hours. The increase in background was noticed shortly after rain began to fall, An- other rain squall started at 1452 hours and the background intensity dropped sharply and continued to decrease to 0.3 mr/hr at 1630 hours. A survey of Site Elmer showed intensities up to 4 mr/hr at 1530 hours, The tent areas showed readings of 3 mr/hr and the interiors of the tents showed 23