1450 
to choose a point Py,’ on the wavefront 7, so that starting 
with o, in Ee | against the radius of the shockwave, this 
direction just intersects with the line P,P, in the center be- 
tween P, and P5. Following this direction throxgh P,' out- 
ward gives the intersection Pz with the wavefront corresponding 
to 7. Now P,' has to be chosen so that the direction a. 
against the connection of Pz’ with the charge just hits the 
connection Py’ Pz in its center. In this way a boundary of the 
undistorted propagation is derived in non-dimensional scale be- 
cause all distances were expressed in charge radii. Thisresult 
is presented in Fig. 5, both for Pentolite and TNT. It can be 
seen that the range of disturbance gets greater for Pentolite 
than for TNT due to its higher pressure. 
Another way of obtaining these two curves could have been 
accomplished by using the fact that the pressure-distance relation 
for Pentolite and TNT as plotted in Fig. 2 is described by two 
nearly parallel curves. Therefore, if the pressure for a TNI charge 
of a certain weight W is given by OF as = f tr). the pressure 
relation for a Pentolite charge of the same weight W would be 
given by ia = f (r/org) with n> 1, thus permitting the sub- 
stitution of a Pentolite charge W by a TNT charge nw, However 
this would not be simpler than the way used here. 
With the curves Fig. 5 available it is now easy to determine 
the boundaries of the peak pressure attenuation for different charge 
depths. The fact that the well known law of similitude is correct 
22 
