(under subclass 323) Sight glasses having means for reflecting or magnifying the liquid in the glass. The reflection or magnification may be accomplished by prismatic formations integral with the glass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
293, for reflectors or magnifiers incorporated with illuminating means.
SEE OR SEARCH CLASS
359, Optics: Systems (Including Communication) and Elements,
642+, for lenses, per se, and subclasses 838+ for mirrors, per se.
374, Thermal Measuring and Testing, 191, for a reflecting or magnifying element combined with an
indicating tube type thermometer, and subclass 193 for an indicating tube type thermometer in which the tube has a cross section causing it to act as an optical element.
