DeZeng’s Refractometer, made by the Cataract Optical Co., Buffalo, NY. Two rotating wheels of lenses, each with 7 openings, are mounted at the eye end; each wheel marked “concave cylinders”. The two wheels, as a unit, can be rotated on the optical axis by means of a geared drive. A peripheral degree scale is marked “axis register”. Within the 9” long outer cylinder is a lens barrel which can be racked in and out. A scale on the topside of this barrel is marked from 0-9, with parts of the scale inscribed “myopia, concave, and spherical”. Fitted behind the focussing knob is a 3” dia. circular scale. A large portion of this scale is marked “hypermetropia convex spherical” with a scale divided from 0-18. The remainder of the scale is marked “myopia concave spherical” with the scale divided from 0-1.5. The instrument is constructed of nickel plated brass, with the various scales and indicators and the cast iron tripod finished in black enamel. Complete, except for a set screw to lock the column height adjustment and a clip-on eye shade. All optics are present and all mechanisms are working. The instrument is marked “DeZeng’s Refractometer, Cataract Optical Co., Buffalo, NY”. Henry DeZeng, Jr., of Geneva, NY, received a patent for this instrument Dec. 3, 1895.
close up view
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