1089 
density of sea water at given temperature and salinity 
4) 
5-58 + 0.0065 T, where T is temperature in degrees 
Centigrade 
L°o 
R 
charge-to-gauge distance in ft. 
The first term only of this equation is usually reported as the 
energy factor (see Sec. d), but in the case of a spherical shock wave 
the second term is not negligible when the charge-to-gauge distances 
are small. Figure 6 shows the second, or so-called "afterflow", term 
of the equation as a percentage of the first, or "primary", term plotted 
against R/Wl/3 A scale of charge radii for TNT is also showm in Fige 6. 
Charge-to-gauge distances (R) in Fig. 6 vary from 5 to 47 feet, and 
the importance of the afterflow term is seen to increase rapidly as RAit/S 
decreases. 
(e) The pressure time curves;:--Average pressure time curve 
for TNT ,is shown in Fige 7. The curve is based on ten records corrected 
to a Wi/3 7p value of 0.242. This curve falls off exponentially out to a 
time t <0, passes through a minimum (Pain? Sa) and a maximum (tins 
ras) to form the “bump characteristic of piezoeleotric pressure time 
curves, and falls off again, at first exponentially and then more slowly. 
ah ae Pecans the Guan eee Pmin> Poax? tin Ve » and 
tmex/ versus W /R are shown in Figs. 8 and 9. The prin and prey 
values follow the similitude law though their scatter is great, and the 
tnip/Wt/5 and eee 5 quantities fall’on a very nearly straight line 
with slight negative slope 
aie Mechanical Gauge Results 
Table A=-II of the Appendix shows the deformations in inches for all 
the ball crusher gauges, and Table A-III of the Appendix contains the 
data from momentum, diaphragm and Modugno gaugese 
Ball crusher gauges were mounted in two ways; four to a block in 
side-on orientation at distances from 5 to 67 feet from the charge, and 
two to a block in face-on orientation at distances 15 to 60 feet from 
the charges The deformations from the gauge blocks in side-on orienta- 
tion have been interpreted in terms of peak pressuree Fig. 10 shows 
log peak pressure versus log wt 3/R for TNT and the best average line 
through the experimental points may be represented by the following 
empirical equation: 
p = 1.92 x 104 (wi/S 7p)? 8 
with a standard deviation of the experimental points from the line of 
2.9%. Peak pressures from piezoelectric gauges are shown as dotted lines 
on the ball orusher peak pressure plots. The method of determining peak 
= ot 
