The traveling ionospheric disturbance of 13 May 1964, discussed by Thome (1968), appears to have had unusually high amplitude and would seem well-suited for further investigation into its possible extension into the southern hemisphere as well as the possible presence of a simultaneous north-bound wave. With f-plot data, supported by tabulated hourly values as well as, in some cases, the actual ionogram, the authors have found some evidence for an extension of the wave into the southern hemisphere with a phase of 180 deg in accordance with Thome's predictions. Preliminary investigations into a north-bound wave seem to reveal a disturbance traveling at approximately the same velocity as the south-bound traveling ionospheric disturbance. (Author).