  We have conducted a search for aperiodic millisecond variability in the
integrated 1 to 25 keV X-ray region of Cyg X-1. We have examined HEAO A-1
archival data and Rossi X-ray Timing Explorer (RXTE) guest observer data for
evidence of excess power above the Poisson noise floor using the relative
integral power analysis and the Fourier transform method. Our results are in
disagreement with the results of Meekins et al. (1984). We attribute the
discrepancy to an instrumental effect for which Meekins et al.(1984) did not
apply a correction. With the correction we see no evidence for excess power
above 25 Hz in the HEAO A-1 data. Our analysis of RXTE data is in agreement
with previously published results of different data sets and shows no sign of
excess power above 30 Hz.
