2022-01-262022-01-26197113695627https://hdl.handle.net/10657/8594From 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 the 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. A temperature range of 2.10°K through 1.00°K was covered. A typical time of flight at 1.75°K for a second sound pulse for stationary conditions was 5.8622 milliseconds. The change in the time of flight for a normal fluid velocity of 0.4 cm/sec at 1.75°K was 0.7 microseconds. Each time of flight for the second sound pulses was measured within [plus-minus] 0.1 microseconds.application/pdfenThis item is protected by copyright but is made available here under a claim of fair use (17 U.S.C. §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