The second magnetospheric tail Ba release of the AMPTE program on May 13, 1985, was observed by several field stations. A Fabry-Perot imager was operated at Mt. Hamilton, California, to measure the line-of-sight velocity of the barium ions in the tail. Simultaneous imaging observations were made from there and from El Leoncito in Argentina. From the two-station imaging data sets we have obtained cloud position by triangulation. The ion cloud bulk velocity was obtained from the position measurements and was intercompared with the Fabry-Perot direct velocity measurements. The triangulated barium ion cloud appeared to be field aligned, and its triangulated direction was in excellent agreement with the Tsyganenko-Usmanov magnetic field model. Following the initial expansion phase and the magnetic cavity formation, the barium cloud became magnetized by the ambient magnetospheric magnetic field. The bulk of the ion cloud was moving very slowly compared to the ambient ion velocity, which was measured by the nearby IRM satellite and which was of the order of several hundred kilometers per second. The slow motion of the barium ions was attributed to an ''electrostatic cavity'' formation at the boundary of the high-density cloud, which excluded the ambient electric field by polarization. Several morphological changes of the ion cloud were obsevbed during the following period, which resulted in the bifurcation of the cloud and the formation of a distinct S shape. Thus the cloud appeared to exclude the ambient convection electric fields, and at the same time it remained responsive to some time-dependent field configuration changes. Thirty-five minutes after cloud release, the cloud suddenly brightened and accelerated in the antisunward direction, tending to take up the local plasma velocity. This acceleration coincided with an increase in the ambient magnetic field and the plasma velocity. There was no clear evidence that the change in the ambient conditions was a direct cause of the observed cloud behavior. ¿ American Geophysical Union 1989