1449 
relation between charge depth d and critical distance (Fig. 4) 
together with the relations plotted in Fig. 2 and Fig. 3 are used. 
However, it is more convenient to investigate the following 
case first: A spherical shockwave, produced by an underwater ex- 
plosion, will be considered in infinitely extended water with a 
sudden disturbance (attenuation) produced at one point P, of the 
shockfront. The shockfront is chosen to correspond to about the 
highest pressure 7 for which the critical angle is known. Accord- 
ing to the above investigations, the disturbance begins to propa- 
gate in a direction differing by that critical angle @ from the 
direction toward the charge. If a series of spheres of equal 
—~ 
4 
wa =~ 
pressures “”,; -< “, are constructed, the sphere 2, is soon 
hit in Pp if we followed the direction given by @ = CPZ) 
CHARGE 
CENTER 
At PP. we would have to follow a direction inclined by 
O,= Osrit (#2) against the connection to the charge. 
However, this would not be the best approximation. We have 
21 
