Three instrumented super pressure balloons were flown throughout the southern hemisphere at 18 mbar, over a period of 5 months. The balloon trajectories, reconstructued from NIMBUS 6 satellite location data, have proved to be valuable indicators of mid-stratospheric structure and dynamics in the Lagrangian frame of reference. Several examples of high zonal and meridional winds are reported. Also shown in the analysis is a feature encountered between 30¿S-40¿S during a 2 week period. The feature appears to be a breakdown of large-scale zonal flow and its replacement by weak cyclonic (stationary) eddies. During the observational period of balloon document the spring reversal (of zonal winds and meridional temperature gradient). This is accomplished by the movement of a planetary scale anticyclonic cell, which itself established the boundaries between the easterlies and the westerlies on a day to day basis. Men zonal wind speed analysis from balloon positions were obtained covering the area 15¿S-6¿S. The results presented here are in substantial agreement with those of Hartmann (1977).