target is used, the rodman takes the rod reading.
(b) San Francisco Rod. The San Francisco rod is used for direct reading only and is
available with three sliding sections.
(c) Chicago Rod. The Chicago rod is available with three or four sections that, instead of
sliding, are joined at the end to each other like a fishing rod.
(d) Lenker Rod. The Lenker rod is a two-section rod similar to the Philadelphia but is
graduated in feet and inches to the nearest one-eighth inch rather than the decimal. The upper section of
the Lenker rod has the graduations on a continuous metal belt that can be rotated to set any desired
graduation at the level of the height of the instrument (HI). To use the rod, set it on the bench mark and
bring the graduation that indicates the elevation of the bench mark level with the HI. As long as the
level remains at that same setup whenever you set the rod on a point, you can read the elevation of the
point directly. In short, the Lenker rod does away with the necessity for computing the elevations.
(e) Lovar Rod. The Lovar rod is a high-precision leveling rod. It is usually T-shaped in
cross section and has the scale inscribed on the metal strip. High-precision leveling rods usually have
tapering, hardened-steel bases and some are equipped with thermometers so that the temperature
correction can be applied. These rods generally contain built-in rod levels.
Figure 5-19. Leveling rods
5-17
EN0591
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