  We report on the analysis of the photometric and spectroscopic properties of
a sample of 29 low redshift (z<0.6) QSOs for which both HST WFPC2 images and
ultraviolet HST FOS spectra are available. For each object we measure the R
band absolute magnitude of the host galaxy, the CIV (1550A) line width and the
1350A continuum luminosity. From these quantities we can estimate the black
hole (BH) mass through the M(BH)-L(bulge) relation for inactive galaxies, and
from the virial method based on the kinematics of the regions emitting the
broad lines. The comparison of the masses derived from the two methods yields
information on the geometry of the gas emitting regions bound to the massive
BH. The cumulative distribution of the line widths is consistent with that
produced by matter laying in planes with inclinations uniformly distributed
between 10 and 50 deg, which corresponds to a geometrical factor f=1.3. Our
results are compared with those of the literature and discussed within the
unified model of AGN.
