1445 
value of pews the corresponding pressure 7 4s derived from 
Fig. 2. Grae corresponding to this pressure 7 is taken 
from Fig. 3. The value which finally corresponds to the used 
value of r..34 is derived as d= Torit sin ees The results 
cri 
thus obtained are plotted in Fig. 4. They show that the approxi- 
mation formulae (16a) and (16b) are adequate for describing this 
relation for depths larger than 10 charge radii. This corresponds 
to a pressure at the critical distance of about 1000 at, which is 
about twice the limit given above. 
Regarding the initial question “if a critical distance 
always exists for any charge weight in any depth”, it has been 
found that this critical distance always exists for the shockwave 
of an underwater explosion thus giving a range of distance between 
charge and surface from this critical distance on to infinity, 
wherein the reflected wave propagates along the primary wavefront 
and attenuates its peak pressure. 
17 
