Advances in hydrostatic leveling with the NPH6, and suggestions for further enhancements

This paper reviews the state-of-the-art of hydrostatic leveling and tilt measurement, with an emphasis on the Pellissier H5, and the National Radio Astronomy Observatory NPH6. Details of the NPH6 design are described, experimental results are discussed, suggestions are made for further enhancements, and additional potential applications are offered.