  From 1994 to 1997 we monitored the optical spectrum of RXJ0019.8+2156. This
supersoft X-ray source is one of only two accreting white dwarfs in the Galaxy
thought to be burning hydrogen on their surface as a consequence of a high rate
of mass transfer from a binary companion. Accurate orbital ephemerides are
derived from radial velocity measure- ments of HeII emission lines, which
exhibit a stable velocity semi- amplitude of 71.2 +- 3.6 km/s. We report the
discovery of transient, low-velocity, bipolar jets. These jets are respresented
by redshifted and blueshifted pairs of emission lines with an outflow velocity
of v cos(i) = 815 km/s, where i is the binary inclination angle. When present,
the jet lines also exhibit an orbital modulation of 71 km/s, which indicates
that the jets are oriented nearly perpendicular to the orbital plane. On most
occasions, the Hline profiles are further altered by P Cygni absorption. We
show that the jets and the P Cygni features have very different temporal
characteristics and binary phase dependence. The jet material and the absorbing
wind must therefore occupy very different geometries. Finally, the measured
mass function is combined with binary evolution models to suggest a limit, i <
40 deg. A particular model invoked to explain a high rate of mass transfer
requires 16 < i < 25. However, at such small inclination it is difficult to
explain the large amplitude of the orbital light curve. By contrast, a simple
model fit to the jet outflow lines indicates an orbital inclination angle of 35
< i < 60.
