1452 
VII. COMPARISON WITH EXPERIMENTAL RESULTS 
There is experimental evidence for small charge depths 
that the reflection of the underwater explosion shockwave is 
unusual (Ref. 10). There is a certain range of distortion 
wherein the peak pressure is smaller and the reflected wave 
arrives later than expected. The boundary between that range 
of disturbance and the free water propagation can be found for 
two conditions which were investigated in Ref. 10. 
In Fig. 7A the results of Fig. 5 of Ref. 10 are replotted. 
They were obtained for 250 gm Pentolite with a charge gauge dis- 
tance of 45.6" (r = 34.8) and different depths; charge and gauge 
were in the same depth. Using Fig. 6 the fact can easily be de- 
rived that the disturbance should reach the gauge only for depths 
d = 3.5 ,» that is for d= 4.6" under the test conditions. The 
results of Fig. 7A seem to give a larger depth; however, these 
measurements scatter considerably and were not obtained with the 
last gauge type (page 10 of Ref. 10). An estimated curve con- 
sidering this scattering of the peak pressures is plotted as a 
broken line in Fig. 10 and gives a critical depth of about 5", 
which does not differ greatly from the calculated value of 4.6". 
In Fig. 7B the results of Fig. 7 of Ref. 10 are replotted. 
These results were obtained for 250 gm Pentolite with gauge and 
charge in constant depth of 4" (a = 3.06) and different distances 
between charge and gauge. From Fig. 6 it was derived that the 
24 
