The physical properties within the two-dimensional flow produced by the reflection of a plane shock of intermediate strength at a wedge, have been determined by analysis of the particle trajectories. The particle trajectories were obtained by high speed photography of smoke tracers within the flow. Trajectories were determined for different initial positions of the tracers relative to the wedge. The conservation of mass equation was used to determine the density at points within the flow. A knowledge of the shock configurations within the flow, together with the Rankins-Hugoniot equation, was used to determine the pressure immediately behind the incident and reflected shocks. The isentropic equation of state was used to determine the pressure after the passage of the reflected shock. The pressure determined in this manner agreed, within the limits of experimental error, with that obtained using a piezo-electric transducer. The temperature, velocity of sound, and particle velocity at points within the flow were also determined. / Graduate / 0605