  We compare the transverse velocity dispersions recently measured within the
Sculptor dwarf spheroidal galaxy to the predictions of previously published
dynamical models. These provide good fits to the observed number count and
velocity dispersion profiles of metal-rich and metal-poor stars both in cored
and in cusped potentials. At the projected radius where the proper motions were
measured, these models predict transverse dispersions in the range 6 to 9.5
km/s, with the tangential dispersion about 1 km/s larger than the (projected)
radial dispersion. Both dispersions are predicted to be about 1 km/s larger for
metal-poor than for metal-rich stars. At this projected radius, cored and
cusped potentials predict almost identical transverse dispersions. The measured
tangential dispersion ($8.5 \pm 3.2$ km/s) agrees remarkably well with these
predictions, while the measured radial dispersion ($11.5 \pm 4.3$ km/s) differs
only at about the $1\sigma$ level. Thus, the proper motion data are in
excellent agreement with previous data but do not help to distinguish between
cored and cusped potentials. This will require velocity dispersion data (either
from proper motions or from radial velocities) with uncertainties well below 1
km/s over a range of projected radii.
