pensate for the duration of the precursor. Likewise the peak positive pressures and positive impulses were those actually read from the pressure-time curves with no correction for the precursor or other factors. Negative impulses were not corrected for the effect of the second shock. Table 6—DATA ON SECOND SHOCK(KING SHOT) Station No. Arrival time, sec Peak positive pressure, psi Blast Line over Water 617.01 617.02 617.03 617.04 617.05 617.06 617.07 617.08 612.02 4.108 4.885 8.353 12.684 Blast Line over Land 6101.01 6101.02 6101.03 6101.04 : 4.048 5.601 7.948 Tabulated data from King shot (Table 5) are presented graphically in Figs. 20 to 29. In Figs. 20 and 21, arrival times are plotted against both slant range and horizontal distance from ground zero. It is readily seen that there is no significant difference in the shapes of the two curves, and consequently the other parameters are plotted against horizontal distance only. The fact that in every instance the shock wave arrived at the land-line stations sooner than at those over water may be attributed to formation of the precursor, which of course traveled faster than the main shock. ‘ Peak pressures measured at the stations over water decayed smoothly with distance from ground zero (Fig. 22), and there was considerably less scatter in the data than in those measured on Mike shot. Peak pressures measured over land exhibited the attenuation believed characteristic when the precursor forms; since the precursor was just beginning to be well formed at the first station on the blast line, this attenuation was actually not observable until the shock wave had reached the second and third stations on the land blast line. At the fourth station the peak pressures had apparently recovered. The dip in peak pressures was not as marked on this test as under similar circumstances in tests at the Nevada Proving Grounds, probably because the sector of land over which the precursor formed was quite narrow and the sharp waveforms over the adjacent large areas of water tended to aid in maintaining the shape of the shock front. Despite the scatter of the data it would appear that the positive-phase durations (Fig. 23) as measured on the land blast line were longer than those measured over water, as would have been expected in view of precursor formation. On the other hand, precursor formation apparently did not decrease the positive impulse (Fig. 24). The increased length of the positive phase over land thus compensated for the diminution of peak positive pressure. Although there was considerable scatter in the data from the negative phase (Figs. 25 to page 50.) ext continues on 39 ases40Wei 3g elected.