1514 
from expected scaling laws which have been observed under 
conditions of Mach reflection near the ground in air blast 
studies may be at least partly associated with distortions 
originating in interaction with the reflecting medium as well 
as with the afterburning effects to which all of the deviations 
are now generally ascribed. 
The development of an accurate theory of the pressure- 
time curve of an obliquely reflected strong shock wave presents 
an extremely difficult if not insoluble problem, and it is 
felt that the most fruitful approach at the present time lies 
in further experimental investigation of pressure-time curves 
in air blast and in shock tubes. Results of such investigations 
may in turn provide fresh assumptions and starting points for 
theoretical development. 
II. The effect of viscous attenuation on 
exponential shock waves. 
Introduction . 
7.1 In view of the fact that shock wave measurements at relatively 
large distances from the origin of the explosion are now becoming 
available, it seems appropriate to examine the effect of viscous 
attenuation upon exponential shock waves. It is a familiar 
result of acoustic theory” that harmonic waves would be subject 
to an exponential attenuation of amplitude with increasing range 
of propagation, and that the attenuation coefficient depends 
upon the viscous forces and the sauare of the frequency of the 
harmonic wave. 
- 38 
