  Dynamic velocity dispersion and mass estimates are given for a sample of five
X-ray luminous rich clusters of galaxies at intermediate redshifts (z~0.3)
drawn from a sample of 39 clusters for which we have obtained gravitational
lens mass estimates. The velocity dispersions are determined from between 9 and
20 redshifts measured with the LDSS spectrograph of the William Herschel
Telescope, and virial radii are determined from imaging using the UH8K mosaic
CCD camera on the University of Hawaii 2.24m telescope.
  Including clusters with velocity dispersions taken from the literature, we
have velocity dispersion estimates for 12 clusters in our gravitational lensing
sample. For this sample we compare the dynamical velocity dispersion estimates
with our estimates of the velocity dispersions made from gravitational lensing
by fitting a singular isothermal sphere profile to the observed tangential weak
lensing distortion as a function of radius. In all but two clusters, we find a
good agreement between the velocity dispersion estimates based on spectroscopy
and on weak lensing.
