The Collaborative International Dictionary of English v.0.48:

Graduator \Grad"u*a"tor\, n.
   1. One who determines or indicates graduation; as, a
      graduator of instruments.
      [1913 Webster]

   2. An instrument for dividing any line, right or curve, into
      small, regular intervals.
      [1913 Webster]

   3. An apparatus for diffusing a solution, as brine or
      vinegar, over a large surface, for exposure to the air.
      [1913 Webster]