target rod

leveling rod, leveling staff

leveling rod A straight rod or bar, designed for use in measuring a vertical distance between a point on the ground and the line of collimation of a leveling instrument which has been adjusted to a horizontal position; usually made of wood and has a flat face which is graduated in terms of some linear unit and fractions thereof, the zero of the graduations being at one end of the rod; may have the graduations on a metal face. On some rods the graduation marks are designed to be read by the observer at the leveling instrument; another type, a target rod, carries a target which is moved into position according to signals made by the man at the instrument; when the target is bisected by the line of collimation, it is read by the rodman.