Drifting pulses of traveling-wave convection

I describe experiments on ``pulses'' of convective traveling waves in an ethanol water mixture contained in an extremely uniform annular cell. In contrast to previous observations, I find that pulses drift continuously, with no long-term change in velocity. The drift velocity vanishes at onset, increases with the distance above onset, and agrees with the results of numerical integrations of the Navier-Stokes equations.