The Collaborative International Dictionary of English v.0.48:

Bushhammer \Bush"ham`mer\, v. t.
   To dress with bushhammer; as, to bushhammer a block of
   granite.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bushhammer \Bush"ham`mer\, n.
   A hammer with a head formed of a bundle of square bars, with
   pyramidal points, arranged in rows, or a solid head with a
   face cut into a number of rows of such points; -- used for
   dressing stone.
   [1913 Webster]