Herschel's fringesn. spectral fringes observed in a prism standing on a plane mirror at the line of separation between the brighter field, due to incident light internally reflected by the prism, and the darker field, due to light externally reflected by the mirror, first observed by Sir William Herschel.
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1890 T. PrestonTheory of Light viii. 153 (heading) Herschel's fringes.