from The Century Dictionary and Cyclopedia

  • n. A plate of colored glass or other transparent medium, interposed in the path of a beam of light to absorb certain rays while allowing the rest to pass; specifically, a screen which cuts out all but the middle portion of the spectrum, so that when it is interposed before an isochromatic plate it becomes possible to obtain satisfactory photographs of celestial objects with refractors which are not photographically corrected.


Sorry, no etymologies found.



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