  We present a measurement of the mean intensity of the hydrogen-ionizing
background radiation field at low redshift using 906 Ly-alpha absorption lines
in 151 quasar spectra from the archives of the Faint Object Spectrograph on the
Hubble Space Telescope. Using a maximum likelihood technique and the best
estimates possible for each QSO's Lyman limit flux and systemic redshift, we
find J(\nu_{0})= 7.6^{+9.4}_{-3.0} x 10^{-23} ergs s^{-1} cm^{-2} Hz^{-1}
sr^{-1} at 0.03 < z < 1.67. This is in good agreement with the mean intensity
expected from models of the background which incorporate only the known quasar
population. When the sample is divided into two subsamples, consisting of lines
with z < 1 and z > 1, the values of J(\nu_{0}) found are 6.5^{+38.}_{-1.6} x
10^{-23} ergs s^{-1} cm^{-2} Hz^{-1} sr^{-1}, and 1.0^{+3.8}_{-0.2} x 10^{-22}
ergs s^{-1} cm^{-2} Hz^{-1} sr^{-1}, respectively, indicating that the mean
intensity of the background is evolving over the redshift range of this data
set. Relaxing the assumption that the spectral shapes of the sample spectra and
the background are identical, the best fit HI photoionization rates are found
to be 6.7 x 10^{-13} s^{-1} for all redshifts, and 1.9 x 10^{-13} s^{-1} and
1.3 x 10^{-12} s^{-1} for z < 1 and z > 1, respectively.
