894 i 
(45) yer) = 24) -g J TAS 
(T) 
where P is any point on T behind the ae front. By (3,1) 
the total vressure st P is 
i t- eA Be GES 
where Pe is the pressure due to e in the absence of eg. The 
corresponding equation for the pressure in front of T follows 
similarly from (4,1), (4,2), (3.2), and (3,3). It is 
(4,5) p(P) = pa (P) + $268) Sa 2M] ds 
where P is any point between T and the hats wave-front and where 
Q is the mirror image of P in T. 
5. The equations (4,4) and (4,5) express the pressure in terme of 
boundary conditions on any infinite plane dividing the gauge 
from the source of the explosion. However, what is really needed 
is an expression for this pressure 
in terme of the motion of the 
gauge. In order to obtain such 
an expression, choose the plane T 
7. of the preceding varagraph to be 
° 
Qo 
. 
initially coincident with the face 
of the gauge. In the following, thia plane is denoted by tT) in- 
stead of T. In Fig. 4, let 
A 
: face of the piston (pistons), 
face of block in which the piston moves, 
- 4. 
