radial distance from ground zero, but the wind information was not always. adequate to determine the angular position, For example, on Koa the es- timated height line bearing was 0 degrees but the sampling aircraft encountered fallout at a polar angle of 50 degrees. For Walnut the 4-hour sampling position given was quite accurate, but the later curving of the height line toward the west could not be predicted. Sampling position estimates were the best of all on Oak and even the most distant points were predicted within 2 degrees in bearing and 3 miles in distance, oy Tables’ B1-B6 give a summary of all the samples collected by aircraft for the project. It will be noted that in addition to the cloud samples taken from the light and variable layer, there were several samples on each shot from lower altitudes, Analytical data for these samples is included since they give information on the variation of cloud composition with altitude (see Appendix D), 2.4 PARTICLE WORK Some investigation of particle characteristics was carried out for all the cloud and height line samples from Shot Koa which were large enough to work with, Approximately one quarter of each filter paper from the cloud samples, and one section from the E-1 sampler, were shipped to UCRL by the first flyaway following the shot, On each sample the filter