  We have found for the first time a Balmer edge feature in the polarized flux
spectrum of a quasar (Ton 202). The edge feature is seen as a discontinuity in
the slope, rather than as a discontinuity in the absolute flux. Since the
polarized flux contains essentially no broad emission lines, it is considered
to arise interior to the broad emission line region, showing the spectrum with
all the emissions outside the nucleus scraped off and removed. Therefore, the
polarized flux spectrum is likely to reveal features intrinsic to the Big Blue
Bump emission. In this case, the existence of the Balmer edge feature, seen in
absorption in the shorter wavelength side, indicates that the Big Blue Bump is
indeed thermal and optically thick.
