1513 
Comments with respect to oblique reflection of strong shocks. 
6.1 The theory developed in the foregoing sections is purely 
linear, applicable only to pressure waves which do not deviate 
appreciably from the restrictions of the acoustic approximatiors, 
and it is not possible to discuss the oblique reflection of 
strong shocks (such as air blast reflected from ground or water 
surfaces) in the same terms. 
Many workers have discussed the strong shock problem, 
but the theory has so far met with rather limited success. In 
view of the results described above, one is led to question 
whether present theories take proper account of the interactions 
occurring at the boundary surface and to speculate as to the 
type of experimental investigation which might cast some light 
on the problem. 
One suggestion (made by Dr. W. D. Kennedy) is the 
systematic comparison of pressure time curves obtained at the 
Plane which is the perpendicular bisector of the line connecting 
two simultaneously detonated charges, with curves obtained 
close to a rigid boundary (such as a piece of armor plate), the 
charge being detonated at a perpehdicular distance from this 
surface equal to half the charge spacing in the first experiment. 
Such an experiment would essentially provide a test of the 
hypothesis that the rigid plane boundary can be replaced by an 
image charge to satisfy the boundary conditions at the surface 
of discontinuity. 
Furthermore, it is conceivable that various departures 
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