DeZeng’s Refractometer was made by the Cataract Optical Co., Buffalo, NY.
Two wheels of lenses, each with 7 openings, are mounted at the eye end. Each wheel is marked “concave cylinders”. The two wheels, as a unit, can be rotated on the optical axis by means of a geared drive. The peripheral degree scale is marked “axis register”. Inside the 9” long outer cylinder is a lens barrel which can be ratcheted in and out.
The scale on the top of this barrel is marked from 0-9, with parts of the scale inscribed “myopia, concave, and spherical”.
Behind the focusing knob is a 3” diameter circular scale. This scale is marked “hypermetropia convex spherical” with the scale divided from 0-18. The rest of the scale is marked “myopia concave spherical” with the scale divided from 0 -1.5.
The refractometer is constructed of nickel-plated brass, with the various scales and indicators and the cast iron tripod finished in black enamel. Henry DeZeng, Jr., of Geneva, NY, received a patent for his instrument on Dec. 3, 1895.