APPENDIX A SHOCK SYMMETRY MEASUREMENTS Copper indenter gauges’? were used to determine whether there were any gross asym- metries of the divergent air shock wave on Mike shot. Groups of 10 gauges were placed at each of two locations at equal radial distances from ground zero; the angle between the radii was 142°36’. Table A.1 presents pertinent information on gauge locations. Table A.1— LOCATIONS OF GAUGES Island Station No. Distance from ground zero, ft Bogallua Engebi 8104 6103 18,568 18,568 Azimuth angle 240°39 98°03’ The assembled gauges were mounted flush with the ground surface on steel stake mounts. No attempt was made to baffle the gauges, inasmuch as this series of measurements wasto be semiquantitative only in that data from one set of gauges were to be compared with those from another set. It was recognized, of course, that had these gauges been used for quantitative measurements of peak pressure it would have been necessaryto provide a suitable baffle ar- rangement as well as to dampthe gauges.':? As used here the gaugesin effect probably inte- grated the pressure-time curve for the first small fraction of a second. Since the duration of the positive phase at the distance of these gauges is approximately 5, sec, the peak pressure could not have decayed appreciably in this fraction of a second. Thus it can be assumed that the gauges did read a fair approximation of peak pressure. Nineteen of the twenty gauges were recovered, and the pertinent data obtained from analysis of the gauge indentations are presented in Table A.2. Peak pressure is proportional to the area of the indentation in the copper disk of the gauge. But, since the ultimate objective was merely the comparison of the two sets of data, it was unnecessary to find the area; the square of the diameter was sufficient. Using X; to represent the square of the diameter for onestatistical set (the readings from the group of gauges on Bogallua), the formula for the standard deviation of the mean can be written _ A 9% * VNxiNx -1) 65