Hildebrandt, A. F.2022-06-222022-06-22196813695610https://hdl.handle.net/10657/9779From ordinary hydrodynamics it is known that an "entrainment" of sound occurs in a moving fluid. A similar effect is expected to take place in the hydrodynamics of helium II. A measurement has been made of the change in time of flight of a second sound pulse as a function of the relative velocity (v[lowered n] - v[lowered s]), where v[lowered n] is the normal fluid velocity and v[lowered s] is the superfluid velocity. From this measurement we may infer how the reference frame of second sound varies with the motion of the normal fluid and superfluid. The change in time of flight was measured within ±0.14 x lO[raised -6] seconds.application/pdfenThis item is protected by copyright but is made available here under a claim of fair use (17 U.S.C. Section 107) for non-profit research and educational purposes. Users of this work assume the responsibility for determining copyright status prior to reusing, publishing, or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires express permission of the copyright holder.Thesisreformatted digital