  We find that a temperature differential can drive superfluid oscillations in
4He. The oscillations are excited by a heater which causes a time dependent
temperature differential across an array of 70nm apertures. By measuring the
oscillation frequency and simultaneously determining both temperature and
pressure differentials we prove the validity of the most general form of the
Josephson frequency relation. These observations were made near saturated vapor
pressure, within a few mK of the superfluid transition temperature.
