The Collaborative International Dictionary of English v.0.48:

Wharl \Wharl\ (hw[add]rl), Wharling \Wharl"ing\, n.
   A guttural pronunciation of the letter r; a burr. See Burr,
   n., 6.
   [1913 Webster]

         A strange, uncouth wharling in their speech. --Fuller.
   [1913 Webster]