The Collaborative International Dictionary of English v.0.48:

Tamping \Tamp"ing\, n.
   1. The act of one who tamps; specifically, the act of filling
      up a hole in a rock, or the branch of a mine, for the
      purpose of blasting the rock or exploding the mine.
      [1913 Webster]

   2. The material used in tamping. See Tamp, v. t., 1.
      [1913 Webster]

   Tamping iron, an iron rod for beating down the earthy
      substance in tamping for blasting.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tamp \Tamp\, v. t. [imp. & p. p. Tamped; p. pr. & vb. n.
   Tamping.] [Cf. F. tamponner to plug or stop. See
   Tampion.]
   1. In blasting, to plug up with clay, earth, dry sand, sod,
      or other material, as a hole bored in a rock, in order to
      prevent the force of the explosion from being misdirected.
      [1913 Webster]

   2. To drive in or down by frequent gentle strokes; as, to
      tamp earth so as to make a smooth place.
      [1913 Webster]