Grade setting and surveyor rod

Claim 1

A telescoping instrument comprising, a plurality of telescoping tubes, including at least one outside tube and one inside tube, means for locking said telescoping tubes at any selected random length, an inwardly inclined guide adjacent the inner end of the inner tube formed by a cut away portion of the wall of the inside tube cut on three sides thereof and bent inwardly of said inside tube, the opposite cut away side edges and said guide forming a guide channel, a rolling element within Said channel and on said inclined guide being free to roll on said inclined guide in said channel radially outwardly of said inner tube when the tubes are turned in one direction thereby wedging said tubes together, and to roll from said narrow peripheral end inwardly to the deepest portion of said channel when the tubes are turned in the opposite direction thereby to free said tubes for telescopic adjustment, said rolling element being completely withdrawable into said deepest portion of said channel within the periphery of said inside tube.