Liquid level indicators

Claim 1

A reflective-type liquid level gauge for a container having a threaded neck and having a quantity of liquid therein, comprising: a circular metal cap having internal threading for securing the same on the threaded neck of the container, said cap having a plurality of arcuate, windowlike cutouts therein, and said cap being provided, on its top surface, with indicia adjacent said cutouts forming a calibrated scale representing the volume of liquid in the container; a circular top formed of clear, transparent plastic molded over and around said metal cap, the indicia on said cap being visible through said transparent plastic top; a concentric tubular, transparent plastic blade member molded integrally with said plastic top and adapted to extend downwardly into the liquid in said container, said blade being aligned with the arcuate windowlike cutouts in said metal cap, and said blade having a curved, spirallike longitudinal edge; and a plurality of stepped, prismatic facet elements formed in said curved longitudinal blade edge, each of said facet elements comprising a plurality of downwardly converging angled faces, said prismatic facet elements being adapted to reflect light upwardly and superpose the same on the scale on the cap thereabove, said facet elements being so designed that light is not reflected upwardly through the facet elements on that portion of the blade immersed in the liquid, whereby light reflected upwardly through the lowermost facet element located immediately above the surface of the liquid will give a precise visual indication on said scale of the volume of liquid in the container.