Abstract: A down-hole pneumatic rotary-percussion hammer drilling apparatus is disclosed. The apparatus includes a drill string for progressively extending into a hole in the earth; an elongated housing connected to the drill string; an impact drill bit, rotationally coupled to the housing, having an engaging surface, an earth impacting surface, a channel, and a plurality of conduits extending from about an exit of the channel to an exit portion of the conduits; a piston within the housing for engaging the engaging surface; and a working fluid handler for energizing the piston with a working fluid. The impact drill bit is rotatable about a longitudinal axis, with the channel and the conduits providing a path of flow of the working fluid from the piston to the exit portions of the conduits. The exit portions are displaced from the longitudinal axis and extend generally downwardly and outwardly. The working fluid emerges from the exit portions and effects rotation of the impact drill bit about the longitudinal axis.