well-spherometern.Optics (now rare) a form of spherometer incorporating a cylindrical aperture, for accurately measuring the radius of curvature of a lens.
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1886 Amer. Jrnl. Sci.131 67 Other and simpler forms of the well-spherometer suggest themselves.
1916 Biogr. Mem. (National Acad. Sci. U.S.A.) 8 263 The other [paper], published in 1886..was upon a well-spherometer of his own invention.