Surface Waves on Bulk Liquid Helium

The velocity of a surface wave on bulk liquid helium is measured as a function of frequency at temperatures above and below the $\lambda$ point. The results do not reproduce those of Everitt, Atkins, and Denenstein. Below the $\lambda$ point our results follow the classical theory, and no two-fluid effects are seen. There is some deviation from simple theory above the $\lambda$ point. The variation in wave amplitude as a function of temperature is qualitatively consistent with the amplitude variation expected from consideration of the specific-heat curve.