more or less arbitrary method for predicting these overpressures. Because it was fairly cer- tain that the yield of Mike shot would be at least 5 Mt, or the equivalent of a burst of 10 Mt in fyee air, a pressure-distance curve for 10 Mt, scaled directly from Greenhouse George and Easy shots,'? seemed to be a feasible starting point. This 10-Mt curve from Greenhouse George and Easy shots is by no means free-air curve. In fact, because of the comparatively low burst heights of these two shots, it might more properly have been considered as representative of surface burst conditions. Consequently, when allowance was made for variations in yield and for indeterminate factors causing variation in shock overpressure at great distances, this method of prognostication seemed as valid as any. Prediction of overpressures on King shot was less uncertain, since the anticipated yield (500 Kt) was morenearly of the order of previously fired weapons. Not only could the yield be estimated more accurately, but set ranges for the gauges in the overpressure region of interest were derived from a pressure-distance curve scaled from experimental data on Greenhouse tower shots."? A factor of 20 per cent was added as a safety factor. 4 CONFIGURATION AND INSTRUMENTATION OF THE BLAST LINE 4.1 Mike Shot The magnitude of the anticipated yield from Mike shot made it mandatory that pressuremeasuring stations be placed at considerably greater distances from ground zero than on earlier tests at Eniwetok and the Nevada Proving Grounds (Table 1). Predicted overpressuresat the eleven station locations (Fig. 1) ranged from a maximum of approximately 320 psi to a minimum of 0.8 psi, and spacing was such that the predicted overpressure at each station was |, approximately half that at the preceding station. Actually, factors such as suitable island lo_ cations and existing recording shelters had to be considered in choosing these locations, making it necessary in some instances to deviate slightly from the basic plan. One station was on a man-made island (Noah) between Bogon and Engebi. As pointed out earlier, the crescentshaped configuration of the island chain made it impossible to align all stations of the blast line on a single radius from ground zero. The four closest stations, 614, 615.01, 615.02, and 610, were essentially on a radial line bearing northeast from the shot island, but the remaining stations were at variant azimuths from the reference line passing through ground zero. AS will be seen from Fig. 1, the shock wave traveled a major portion of its path across water be- fore reaching Stations 611.01, 611.02, 611.03, 613.01, 611.04, 613.02, and 612.01. Table 1—- LOCATIONS OF MEASURING STATIONS FOR BLAST LINE ON MIKE SHOT Island Station Azimuth Distance from Type of mount* No. (from north) ground zero, ft Line i Line 2 Teiteir Bogairikk Bogon Noaht Engebi Muzin Bokon 614 615.01 615.02 610 611.01 611.02 611.03 12°11 51" 72°44" 45" 73°01'08"’ 72°49' 25" 93°16'38"" 105°§1/31"" 111°18’50"’ 4,402 5,900 8,250 11,490 15,900 21,412 30,354 GB GB GB SOB SOB SOB SOB GB GB GB SOB PS Ps Ps Aomon Runit Parry 611.04 613.02 612.01 109°55’ 37" 127°18°57" 144°59'56" 47,574 74,884 114,240 SOB SOB SOB —~wPSS SOB PS Aitsu 613.01 111°34717” 36,708 SOB *GB, ground baffle; SOB, side-on baffle; PS, pitot static tube. TA pipe mount on the reef between Bogon and Engebi. 13 SOB Shelter No. and recorder 600(A) 600(A) 600(A) 600(B) 601(A) 602(A) 603(A) 603(B) 604(A) 605(A) 606(A)