The radioactive debris dispersed quickly throughout the world and all but a few stations experienced measurable fallout at some time during the series. Examination of the daily results showed spread in time also. When fallout occurred at a station it usually lasted for several days, a . fact tending to improve the reliatility of the station totals. It frequently happened during continental tests tnat most of tne fallout of a period occurred on a single day or two days. During the recent series this pattern was less common. 4. Acknowledgment The sampling network included weather stations of the U. S. and Canadian Weather Bureaus, the Army, the Navy, the Air Force and the Coast Guard. Most of the military stations were operated by Air Weather Service per sonnel. Two stations in Japan were manned by the Atomic Bomb Casualty Commission and one in Canada was provided by the Chalk River Atomic Energy Installation. The armed forces and the Weather Bureau cooperated also in other ways and the Weather Bursau is studying the data and will issue a report. Phases of the survey to be reported separately were accomplished in . aia cooperation with Joint Task Force Seven and the Navy.