The dispersion curve for elementary excitations in He H at low temperatures and at the vapor pressure is evaluated using inelastic neutron scattering data. It is found that this dispersion curve is consistent with recent specific heat measurements of high resolution. We represent the dispersion curve by means of cubic splines, and emphasize the need for further neutron scattering studies at low momentum transfer.

A continuously balanced impedance bridge under computer control constructed for a cryogenic thermometry application provides a few ppm resolution in resistance ratio measurements. The use of IEEE-488 computer bus-compatible commercial equipment reduces the design mainly to that of software and permits flexibility in the balancing procedure.