Intense electron microbursts were detected by means of bremsstrahlung X ray measurements during a period of strong substorm activity on July 31, 1973. The time resolution of the X ray data was sufficient to examine in detail the temporal and spectral features of individual microbursts in differential energy windows of 25--50, 50--75, and 75--100 keV. The duration (full width at half maximum) of a typical microburst was ~150 ms; periodic spacings in multiple microbursts were of the order of 0.5 s. Both of these characteristic times are at the low end of the range of corresponding times observed for microbursts at higher latitudes. With respect to the mean spacing in multiple microbursts, this result is consistent with precipitation models which predict an L dependence for this characteristic time. Power spectra of long segments of data showed that the microbursts tended to cluster in groups spaced from 3 to 7 s apart. Significant substructure of the order of 30--70 ms was evident in many microbursts. Double-peaked bursts were frquently observe in the 75- to 100-keV channel. Microbursts exhibiting substantially different rise times, of the order of 30 and 70 ms, could also be distinguished in the 75- to 100-keV channel.