(under subclass 213) Subject matter wherein the light to be measured falls on the pupil of an observer to control the size of the pupil as by contraction or dilation of the iris, together with means to permit the observer to see his pupil and to compare or measure the size or tangent of the pupil as the light to be measured falls thereon.
SEE OR SEARCH THIS CLASS, SUBCLASS:
372+, for structure to measure articles for some type of dimensional size.
SEE OR SEARCH CLASS
33, Geometrical Instruments, for devices which visually measure by means of scales or standards or markings a linear dimensional size.
351, Optics: Eye Examining, Vision Testing and Correcting,
