is satisfactory depending upon acceptable flexibility for operation as the cable is being inserted into the hole the upward push by the drive mechanism 22 is resisted by the frictional back pressure of the surface of the hole 16 thus the cable is in slight compression particularly near the entrance of the hole therefore the cable requires a certain amount of rigidity because the strands must be pushed to near the top of the hole rotation of the cable in a direction in which the strands are twisted renders the cable more rigid and thereby makes its insertion into the hole easier additionally outcroppings of rough rock surface within the hole can catch on the top surface of the cable as it is inserted and cause it to buckle or bend however with rotation during insertion the twisting motion of the cable causes it to pass the outcropping and continue its upward movement fig3 shows a hollow filament or open duct 24 located in each of the four strands 20 each such duct extends from one end of the cable to the other to allow air to escape as the cable is inserted simultaneously with the insertion of the cable a bonding agent 25 is introduced into the annulus shaped cavity defined between surface 16 and cable 18 the bonding agent which will be described in more detail is introduced through a plurality of passages 26 in face plate 27 face plate 27 presses against a sealing gasket 28 positioned against the roof 14 to prevent leakage of the bonding agent beneath face plate 27 is a rotating plate or cable rotor 30 having a patterned opening 32 the profile of which corresponds to the shape of the cable thus plate 30.