Prismatic compass

Prismatic \Pris*mat"ic\, Prismatical \Pris*mat"ic*al\, a. [Cf.
   F. prismatique.]
   1. Resembling, or pertaining to, a prism; as, a prismatic
      form or cleavage.
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   2. Separated or distributed by a prism; formed by a prism;
      as, prismatic colors.
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   3. (Crystallog.) Same as {Orthorhombic}.
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   {Prismatic borax} (Chem.), borax crystallized in the form of
      oblique prisms, with ten molecules of water; --
      distinguished from octahedral borax.

   {Prismatic colors} (Opt.), the seven colors into which light
      is resolved when passed through a prism; primary colors.
      See {Primary colors}, under {Color}.

   {Prismatic compass} (Surv.), a compass having a prism for
      viewing a distant object and the compass card at the same
      time.

   {Prismatic spectrum} (Opt.), the spectrum produced by the
      passage of light through a prism.
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