  We present velocities for 230 stars in the outer parts of the globular
cluster M15 measured with the Hydra multi-object spectrograph on the WIYN
telescope. A new Bayesian technique is used for analyzing the data. The mean
velocity of the cluster is -106.9+/- 0.3 km/s. Rotation with an amplitude of
1.5+/- 0.4 km/s and a position angle of 125+/-19 degrees is observed and the
model including rotation is marginally favored over one without rotation. The
velocity dispersion decreases from the center out to about 7' and then appears
to increase slightly. This behavior is strikingly different from the continued
decline of velocity dispersion with increasing radius that is expected in an
isolated cluster. We interpret this as an indication of heating of the outer
part of M15 by the Galactic tidal field.
