The Collaborative International Dictionary of English v.0.48:

Sicker \Sick"er\, v. i. [AS. sicerian.] (Mining)
   To percolate, trickle, or ooze, as water through a crack.
   [Also written sigger, zigger, and zifhyr.] [Prov. Eng.]
   [1913 Webster] Sicker

The Collaborative International Dictionary of English v.0.48:

Zigger \Zig"ger\, Zighyr \Zig"hyr\, v. i. (Mining)
   Same as Sicker. [Prov. Eng.] --Raymond.
   [1913 Webster]