thaumatrope

from The Collaborative International Dictionary of English v.0.48
Thaumatrope \Thau"ma*trope\ (th[add]"m[.a]*tr[=o]p), n. [Gr.
   qay^ma a wonder + tre`pein to turn.] (Opt.)
   An optical instrument or toy for showing the persistence of
   an impression upon the eyes after the luminous object is
   withdrawn.
   [1913 Webster]

   Note: It consists of a card having on its opposite faces
         figures of two different objects, or halves of the same
         object, as a bird and a cage, which, when the card is
         whirled rapidly round a diameter by the strings that
         hold it, appear to the eye combined in a single
         picture, as of a bird in its cage.
         [1913 Webster]
    

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