During a 5-hour interval on November 9, 1972, Imp 7 detected strong earthward plasma flows within the plasma sheet. The plasma flow exhibited a sequence of nine clear temporal pulsations in which the bulk speed varied from zero up to 1000--1500 km/s. The pulsations occurred at 15- to 30-min intervals. These speed variations are shown to be positively correlated with changes in the standard deviation of the magnetic field (15-s accumulations). During the flow pulsations, ground magnetograms exhibited only weak high-latitude substorm activity, which is consistent with the Heos 2 detection of low values for the interplanetary field, with only a moderate southward component. Closer to earth, ATS 5 and Imp 6 detected some plasma heating during the period of Imp 7 flow pulsations. However, there was no evident periodicity corresponding to the Imp 7 flow pulsations in any of the other magnetospheric or solar wind data. Integrated over the 5-hour interval, the strong plasma flows injected roughly 1022 ergs into the inner magnetosphere, yet both the solar wind and the ground magnetogram data are consistent with the magnetosphere having been in a relatively quiet state with only weak substorm activity along a contracted auroral oval. We suggest that the pulsations may be evidence that tail reconnection is inherently unsteady, with 10- to 30-min periods.