device. If the predominant direction of fallout cannot be determined, then sampling stations should be located in all directions from ground zero. Such an array should be avoided where possible because of the large amount of wrk required to maintain the resulting large number of stations. Water-based stations should be used at the Pacific Proving Grounds to provide proper area coverage to document the fallout. Land stations at the shot atoll do not by themselves provide enough fallout documentation. Larger bases, such as barges, should be used where practicable as instrument platforms in the lagoon rather than the rafts used at CASTLE. The rafts used at CASTLE were inadequate bases on which to mount fallout collectors. Seas in the lagoon are generally so rough that it is difficult for personnel to moor rafts to buoys, transfer equipment from boats to rafts,and work on the rafts. New types of fallout collectors should be designed to sample fallout in locations subject to more or less continuous salt water spray and occasional immersion before and after the instrument has operated. Present fallout collectors, though adequate to keep ordinary rains from working parts, are not adequate when mounted on low rafts at sea stations and at land stations subject to water waves from close-by nuclear detonations. 102