1460 
This is in good agreement with the result of J. von 
“Neumann (Ref. 1) who gives 
fa} = ‘ 
@, ~ 157 Ye, 
while it was derived here 
2] — ~ 
Oe atyl,. =/5! a, 
According to the critical distance Ee for reflection 
of an underwater explosion shockwave at a free surface, a critical 
distance can be derived for the reflection at a rigid boundary: 
Ps 
@ vorit (30) 
which is correct only for small pressures ( 7 S 500 at) also. 
A general result, which was derived by J. von Neumann in 
Ref. 1 can easily be reproduced here: 
Combining (25) and (26) gave (27), and it was found 
i (@) ~ 
ee hr a 
The minus sign for the root gives no physical sense and 
is neglected. This result can be transformed with (28) and gives 
_({ Om 
Ori 2 (tay! (37) 
and 2 
fi ee NEN SOL ge 
+¥/-(2) 
7 «= 
32 
