in Figs. 2 and 3. The theoretical curve is based on fission products from slow neutron fission and the assumptions that there is no fractionation and that the radionuclides are dis~ tributed over an infinite plane, while at Rongelap measurable amounts of activity remained on the trees. The actual measure- ments fit closely to the theoretical decay curve for Rongelap islet and at least for the first four years after fallout at Kabelle islet in spite of the assumptions made in determining the theoretical curve and the variability of the field measurements. The measurements on one small islet may vary by a factor of more than three, even when the identical instrument is used by the same person. Decline following first storm About two weeks after initial contamination there was a storm with heavy rain, and a subsequent reduction in gamma dose rate somewhat greater than would have been expected on a theoretical pasis (2/4), (Fig. 2). Fallout in 1956 and 1958 The rises in gamma dose rates in 1956 and 1958 were due to operations Redwing and Hardtack. Even though there was a measurable amount of contamination, as was seen by the shortlived radionuclides present and by following the beta decay rates in plants collected in 1958, the total contribution was