Squared time derivatives of output powers of the Argonne and Maryland gravitational radiation detectors are written on magnetic tapes at Argonne and Maryland every 0.1 sec. A computer files the threshold crossing times. A coincidence is a pair of identical crossing times of both tapes. The accidentals rate is measured by repeating the procedure for a sequence of time delays in either channel. A significant excess of coincidences is found at zero delay. © 1973 The American Physical Society.