473 
is identical with that employed for the calculation by the theory of 
Kirkwood and Bethe. The initial value of the reduced energy variable, 
Q) = 258, was calculated by means of Eq. 8.3822 This value corresponds 
to the value €, = 572 cal./gm. or, with an explosion energy of 1060 cal./ 
gm., to an energy of the gas bubble at its first maximum of 478 cal./gm. 
The remarkably good agreement of the latter figure with experiment is 
probably fortuitous, 
The calculated peak pressure-distance curve is compared with the 
predictions of the kinetic enthalpy propagation theory of Kirkwood and 
Bethe in Figure 8.1. At large distances, the results obtained by the sim- 
ilarity restraint theory are about 18 percent lower than those obtained by 
the kinetic enthalpy propagation theory. In view of the very different 
nature of the two theories, it may be concluded that the two theories are 
in satisfactory agreement. 
The application of the similarity restraint theory to the calcula- 
tion of the shockewave parameters for particular explosives has been facil- 
itated by the preparation of tables of the integrals of Eqs. 8.24 for a 
number of initial values of the peak pressure and reduced energy varianies=2) 
These tables permit the immediate evaluation of the shock-wave parameters 
for particular explosives after the initial conditions have been computed, 
and they may be employed with curve-fitting techniques for the extrapolation 
of experimental results, measured over a limited range of distance, to 
larger or smaller distances from the charge. 
32/ The thermodynamic properties of the explosion products of TNT were 
taken from a tabulation by J. G. Kirkwood, S. R. Brinkley, Jr., 
and J, M. Richardson, OSRD Report 2022 (1943). 
