The data from observations of two important radio galaxies, Cygnus A and Hercules A will be analyzed and interpreted. The study of Cygnus A is expected to improve our knowledge of properties of jets in powerful radio galaxies, to improve our understanding of the processes at work in the hotspots, to define the properties of the newly discovered filamentary structures inside the lobes, and to characterize the radio spectrum as a function of position. In contrast to the case of Cygnus A, which seems to be readily understandable in terms of current notions of radio source structure, Hercules A presents many puzzles. The study will aim particularly at elucidating the system of "puffs" that appear to emanate from one side of this galaxy. These studies will be relevant to many issues in the theory of extragalactic radio source structure, including confinement and beaming in high luminosity jets, flow conditions at the jet working surface, source energetics, and source ages.
