"Progress is reported in an evaluation of fission product concentration in rain as a function of time, location, and meteorological setting. Data on rainfall collected at Westwood, N. J., were analyzed for information on the mechanisms of fallout deposition, seasonal variations in fallout, the stratospheric residence time of W/sup 185/ resulting from Operation Hardtack, and the accuracy of pot samplers for sample collection. Data from other collection stations were also analyzed for consistency with Westwood data."