The Collaborative International Dictionary of English v.0.48:

Tregetour \Treg"et*our\, n. [OE. tresgeteor. See Trans-, and
   Jet a shooting forth.]
   A juggler who produces illusions by the use of elaborate
   machinery. [Obs.]
   [1913 Webster]

         Divers appearances
         Such as these subtle tregetours play.    --Chaucer.
   [1913 Webster]