Shot6: (At Eniwetok) Over 1000 rf/hr in tue immediate vicin- ity ofground zero, dropping to 17 to 32 r/hr on the islands westward and 1 to 6 r/hr eastward from ground zero. Within the atoll, there was no apparent trend of radioactive rarticle size distributicn with distance, direction,or time. The approximate number-median diameters of samples collected ranged from 5 to 20 pe. Up to forty-three per cenit of these particles were under 10 pe Shot 1 particles appeared to be coral or crystalline; those from Shot 3 appeared to be mostly crystalline, ashlike, or fused. In particles from 149 to 1000 wp, the percentage of particles with activity on the outside generally increased directly with size, while the percentage of uniformly radioactive particles generally decreased with size. These two types of particles accounted for about 90 per cent of the radioactive particles examined. Activity was scattered randomly throughout the remaining 10 per cent of particles. There was no apparent correlation between the location of activity on the particles and their physica] appearance, No conclusions covld be drawn about the presence or absence of radioactivity in the base surge,because no samples were obtained in the base-sirge region.