  Crystal grains of solid $^4$He can move in relation to each other even when
embedded inside the solid. In this work, we characterize a macroscopic motion
of solid hcp $^4$He composed of such grains. Motion is induced by applying an
external torque to the solid contained inside an annular channel mounted on a
torsional oscillator. In order to characterize the surface of the moving solid,
we developed an in-situ flow detection method using a sensitive "microphone"
embedded in the wall of the channel. Motion is detected by counting the
vibrations induced by rows of He atoms moving past the microphone. Such
vibrations were detected only at T=0.5K, our lowest temperature. At this
temperature, the measured dissipation associated with the solid He is zero
within our accuracy. Our results indicate that the orientation of the surface
of the moving solid is the (0001) basal plane of the hcp structure. At T=0.5 K,
we found that for speeds < 7 micrometer/sec, the solid flows without detectable
friction.
