at several] Underwater Sound Transmission Experimental Facilities (USTEF) stations in the Pacific and at similar research stations {in the Atlantic The studies were designed to lead to a better understanding wave forms, indicating that the shock had picked up water. For these two shots, the gage group was lo- cated near the edge of the water The force plate and density gage seemed to be suitable for field use, but study was needed on their response to dust. of the underwater sound propagation and to determine the accuracy of device yield figures that might be extracted from the measurements. Shots 2, 4, 5, and 6 were monitored by detecting stations located on the California coast and at Bermuda. No clear-cut signals were recorded which could be attributed to sources at either Bikini or Eniwetok. It was concluded that the positions of the shots, inside the lagoon and on the atoll rim, precluded the coupling of energy into the SOFAR channel in the frequency channel to which the instruments were sensi- “Instrumentation for Projects 1.2a, 1.3, and 1.7” (WT-907), Sandia Corporation; R. H. Thompson, project Officer. The primary objective of this project was to make support measureinents of pressures, shock winds, and ground accelerations from large scale detonations for Projects 1.2a, 1.2, and 1.7. A secondary objective was to field-test several new gages. tive. “che primary measurements were made with Wiancko and Sancia pressure transducers, differential-pressure y-tubes, and accelerometers. Other instrumentation used included drag q-tubes, forecplate stagnation~presaure gages, density gages, temperature gages, and displacement gages. Of the records taken on 112 data channeis, 99 gave complete infurmution; 6 gave information up to arrival of the shock wave; and seven gave no information. Project 1.6 ‘‘Water Wave Measurements” (WT-910), Scripps Institution of Oceanography; R. R. Revelle and John D. Isaacs, Project Officers. The objective was to study water surface waves generated within the lagoon by a large-yield surface detonation. The measurements of wave height were obtained from underwater gages designed to record the hydrostatic pressure vibrations produced by the Preliminary evaluation of new inatrumentation passing wave. In addition, surveya of inundation levels on land areas wcre made. In contrast to the Ivy-Mike results, Castle data indicated that the recorded waves did emanate from the central region of the detonation. The time of arrival of the first crest of the direct water wave showed a indicated that: (1) the density gage needed better waterproginvg, (2) the force plate operated satisfac- torily, (3) the temperature gage was still too delicate for field use, (4) the gage q-tube was easy to cali- orate but needed waterproofing to protect the canti- lever f-om custing and to protect the E-coil, and (5) propagation velocity fitting the relation V = (gh)!/?, the differential cressure gage was easy to calibrate but needed wate: proofing. where h is an average depth of 170 feet assumed for the Bikini lagoon. Refraction and reflection against the reef or shoreline can significantly reduce or amplify the destructive capabilities of water waves at termination. Where focusing effects and the reflectionrefraction potential of the adjacent lagoon topography Project1.4 “Underwater Pressure Measurements” Project Officer. This project was designed to measure the under- water pressure-time field produced by large-yield surface bursts. Pressure-time measurements and oall-crusher-gage measurements were obtained for was a minimum, the heaviest inundation and potential damage occurred with the first crest. These results were obtained uncer particular conditions of geometry, in a region of relatively shallow depth; such damage Shots 2, 4, 5, and 6; ball-crusher-gage measure- ments were obtained for Shot 1. The gages were lo- criteria are applicable to conditions that depart only slightly from those under which the data were obtained. cated as close ag 6,000 feet from ground zero. Some difficulty with instrumentation was experienced during the operational phase; as a result, a Project 1.7 “Ground-Motion Studies on Operations Ivy and Castle” (WT-9002), Sandia Corporation; W. R. Perrett, Project Officer. lesser amount of reliable data were obtained than uriginally anticipated. The major result of the recorded data indicated that the maximum, or peak, This project was designed to obtain measurements underwater pressures are of the same magnitude as the air-blast peak overpressures at the same range. of three components of ground acceleration on Shota 3 and Echo. These measurements were to be closer in to ground zero than those obtained on Ivy-Mike and it was concluded, therefure, that a nuclear weapon detonated on the surface of a relatively shallow water layer, under conditions as experienced on the Castle hence augment and extend those measu ements pre- shot, produces underwater pressures which are probably of small military significance. Project 1.5 “Acoustic Pressure Signals in Water (SOFAR)” (WT~909), Office cf Naval Research; J. W. Smith, Project Officer. The objectives were to make special observations viously obtained. Unfortunately, the yield of Shot 3 was only about a tenth of that expected and Shot Echo was cancelled. As @ result of the low actual yield of Shot 3, set ranges for the gages were too high, recording a verylow signal amplitude. With such a low signal-to-noise ratio, the identification of phase arrival, frequencies, 107