Wallace Campbell: The Twelfth Bruce Medalist

Readers of this series may recall that in the late nineteenth century Hermann Carl Vogel [Mercury, Nov/Dec 1990] obtained the first reliable measurements of radial velocities of stars--their speed toward us or away from us. It was Vogel's laboratory measurements of Doppler shifts on photographs of stellar spectra which allowed him to bring uncertainties in these velocities to +/- 3 kilometers per second, a factor of ten better than William Huggins [Mercury, Sep/Oct 1990].