The year 1992 marks the sesquicentenary of Doppler's paper on his effect and the centenary of Vogel's application of the Doppler effect using photographic spectroscopy to determine reliably the velocities of stars in the line of sight. This article discusses the circumstances in which these two classical papers were written and discusses the reasons for the fifty-year interval between the enunciation of the Doppler effect and its practical application to starlight.