The Collaborative International Dictionary of English v.0.48:

Calking \Calk"ing\, n.
   The act or process of making seems tight, as in ships, or of
   furnishing with calks, as a shoe, or copying, as a drawing.
   [1913 Webster]

   Calking iron, a tool like a chisel, used in calking ships,
      tightening seams in ironwork, etc.
      [1913 Webster]

            Their left hand does the calking iron guide.
                                                  --Dryden.
      [1913 Webster]