  We present measurements of the masses of 20 X-ray luminous clusters of
galaxies at intermediate redshifts, determined from a weak lensing analysis of
deep archival R-band data obtained using the Canada-France-Hawaii-Telescope.
Compared to previous work, our analysis accounts for a number of effects that
are typically ignored, but can lead to small biases, or incorrect error
estimates. We derive masses that are essentially model independent and find
that they agree well with measurements of the velocity dispersion of cluster
galaxies and with the results of X-ray studies. Assuming a power law between
the lensing mass and the X-ray temperature, M_2500 T^alpha, we find a best fit
slope of alpha=1.34^{+0.30}_{-0.28}. This slope agrees with self-similar
cluster models and studies based on X-ray data alone. For a cluster with a
temperature of kT=5keV we obtain a mass M_{2500}=(1.4+-0.2)\times
10^{14}h^{-1}Msun in fair agreement with recent Chandra and XMM studies.
