  The transverse velocity of a spiral galaxy can be measured to an accuracy
$\sim 60\,\kms$ by making parallax observations of quasars being microlensed by
stars in the disk of the galaxy. To make the measurement, a quasar must be
located behind the disk of the galaxy between about 1 and 2 scale lengths from
the center. The quasar must then be monitored for microlensing events and the
events followed simultaneously from the Earth and a satellite in solar orbit,
preferably at $\sim 30\,$AU. A systematic search in a volume within
$21,000\,\kms$ could locate quasars with $B<23$ behind a total of $\sim 1900$
galaxies. The rate of lensing events (and hence galaxy velocity measurements)
would be $\sim 3\,{\rm yr}^{-1}$. The events would have typical characteristic
times $\omega^{-1}\sim 3\,$yr. Under the assumption that the mass spectrum of
lensing objects is the same in other spiral galaxies as in our own, the
observations could be used to measure the Hubble parameter to an accuracy of
5\%.
