I. 
1253 
GENERAL DESCRIPTION OF PROBLEM AND RESULTS 
i. When a finite shock-wave in a fluid is reflected 
from a solid body, the pressure on the body at first rises 
nearly instantaneously and then decays to its initial value 
when the reflection is completed. In theoretical studies 
of reflection attention has been directed mainly toward the 
initial increase in pressure. No attempt has yet been made 
to determine the subsequent decrease in pressure when the 
incident wave falls obliquely on the reflecting surface. 
When, however, the incident wave is reflected normally, the 
situation is much simpler. In this case Chandrasekhar 1) 
has worked out the complete pressure-time curve for air by a 
numerical method based on Riemann's treatment of motions ef 
finite amplitude. The purpose of this report is to extend 
his work to other fluids, particularly water. In so doing it 
has been found possible to replace his numerical method by 
an analytical one. 
2. Let a laterally infinite, rigid wall be struck 
by a normally incident, plane shock. (An exactly equivalent 
hydrodynamical situation is presented by the head-on 
collision of two equal shocks, and so results obtained 
here ere applicable to such a collision.) Since the wave 
incident on the wall is plane, it is able to propagate 
in only two directions - forward and backward. In order 
to describe this wave completeiy it 1s necessary to 
= 1 -« 
