  The luminosities of globular clusters are found to correlate with their
half-light radii. The most luminous clusters have half-light radii r ~ 3 pc.
Mean cluster luminosities are < Mv > = -6.64 +/- 0.26 for r < 2.0, < Mv > =
-7.44 +/- 0.20 for 2.0 < r < 4.0 pc, and < Mv > = -6.57 +/- 0.21 for clusters
with r > 4.0 pc. An even fainter value < Mv > = -5.85 +/- 0.36 is found for
large clusters with r > 8.0 pc. These results possibly weaken confidence in the
conclusion that the peak of the globular cluster luminosity distribution is a
universal standard candle. In the outer Galactic halo globular clusters with
red horizontal branches are fainter by about a factor of ten than are clusters
with blue and intermediate color horizontal branches. Among clusters with
Galactocentric distances > 10 kpc there appears to be a clear dichotomy between
normal clusters (which all have [Fe/H] < -1.2) and the anomalous relatively
metal-rich clusters Pal 1, Pal 12 and Ter 7, which are both unusually faint (Mv
> -5) and relatively metal-rich ([Fe/H] > - 1.0). This suggests that these
relatively metal-rich halo clusters may have had an unusual evolutionary
history.
