For accurate measurement of the radius of curvature of spherical lenses or curved surface objects. Three-pronged brass table with three pointed legs carries a vertical main scale from 10 - 0 - 10 mm on one of the prongs, and a micrometer scale on a brass disc with 100 divisions. The table has a screw at its center with a pitch of 1 mm giving a least count of 0.01 mm.