Abstract: An instrument for establishing a horizontal plane for leveling ceilings, tables, floors and the like, consisting of a reference head having a translucent liquid reservoir, an adjustable field head, and a hose for interconnecting the two heads. With the level of liquid in the reservoir calibrated to correspond to the desired elevation, the liquid level at the field head at the other end of the hose will correspond to the selected reference level, thereby providing a means for defining a horizontal plane which is independent of a continuous line of sight. A plurality of datum scales in visual juxtaposition with the reference head reservoir and correlated to the mounting channel or to the base of the reference head provide reference marks at known vertical distances from these mounting points.