Abstract: A normally generally horizontal cylindrical open-ended casing having a cylindrical rotor coaxially mounted therein for rotary and axial movements, the rotor having a rear end forwardly spaced from the rear end of the casing and a boring head on its front end projecting forwardly of the front end of the casing. At least one motor is mounted in the casing for imparting rotation to the rotor. A pair of fins are mounted in the casing for movements radially through openings in the casing to engage earth material to control rotation of the casing on its axis in the ground. Fluid pressure rams operate to impart limited axial movements to the rotor and boring head relative to the casing and radially extending and retracting movements to the fins. Controls for the rams and motor provide for common operating pressures to the rams and motor.