487 
where &, the fraction of the total explosion energy delivered to the 
first shock, can be estimated from measurements of the maximum bubble 
radius from spherical charges, or in the absence of such information, 
roughly approximated by the value 1/2, A more refined analysis for the 
determination of the initial shock-wave energy, similar to that for the 
spherical shock wave, has not been carried out for the cylindrical case, 
10. Comparison with the Experiment 
We conclude the discussion of the theory of the propagation of 
underwater shock waves by comparing with experimental values the results 
of the calculation of shock-wave parameters by the two theoretical proce-- 
dures which have been outlined for two typical explosives. The kinetic 
enthalpy propagation theory and the similarity restraint propagation theory 
are based on entirely different theoretical assumptions, and it is therefore 
of interest to compare the predictions of the two theories and also to com- 
pare the theoretical predictions with experiment. A discussion of the tech- 
niques for the experimental determination of shock-wave parameters will be 
found elsewhere in this work, 20/ 
The use of the peak approximation to the kinetic enthalpy on the 
gas surface ir the kinetic enthalpy propagation theory and the assumption 
of an exponential Lagrange energy-time curve in the similarity restraint 
propagation theory results for each theory in the prediction of an exponen- 
tial form of the Euler pressure-time curve. The exponential pressure-time 
36/ See also R. H. Cole, Underwater Explosions, Princeton University 
Press, Princeton, New Jersey (1948). 
