The Collaborative International Dictionary of English v.0.48:

Jigging \Jig"ging\, n. (Mining)
   The act or using a jig; the act of separating ore with a
   jigger, or wire-bottomed sieve, which is moved up and down in
   water.
   [1913 Webster]

   Jigging machine.
   (a) (Mining) A machine for separating ore by the process of
       jigging.
   (b) (Metal Working) A machine with a rotary milling cutter
       and a template by which the action of the cutter is
       guided or limited; -- used for forming the profile of an
       irregularly shaped piece; a profiling machine.
       [1913 Webster]