1127 
apr Pee -0.6580 - 0.2039 Tr + 4 [=0? + 156.25 | & nillisec 
2 held 
for rg <R (20 
(t, - ty 20 for r¢ > R) (21) 
as before, and at 
t £2 - ty = 0.0066 rq for Tr, < R (22) 
vets ketene | 
t be t, = 0.6580 + 0.2105 [= (rp + 156.25) millisec 
for rp 2R ; (23) 
For double-ended detonation, there is a second critical distance R', 
at which t fyp = to. When rg =R', tp = tp, and when rp SR’, 
tp = t J/g- The theoretical lines for tp - ty, ty - ty, t Bo - ti 
and t f Wey t, are given in the lower portion of Fig. 6, and the 
observed values of tp, - ty are plotted. The critical distances 
R! = 23.4 ft, and R = 48.4 ft are indicated by vertical dotted lines. 
te - t, slowly approaches a limiting value of 0.658 millisec as T> 
increases. 
The theoretical expressions for t,, t,, tg,» t 4/2) and tp are 
summarized in Table III, and the appearance of these points on the 
pressure-time curves is indicated in Figs. 4 and 5. 
For all charge orientations and conditions of firing, the 
observed time intervals fall further below the calculated time 
intervals as the charge-to-gauge distance increases. This is what 
one would expect from the assumption of constant shock-wave velocity 
in calculating the time intervals. Actually, the latter part of the 
pressure wave, travelling in a higher pressure region, has greater 
velocity, and gradually overtakes the shock front. The greater the 
distance from the charge, the more pronounced will be this overtaking 
effect. 
-17- 
