level rod[′lev·əl ‚räd]
a measuring device used in leveling; it is a wooden stick 3–4 m long with a rectangular or I-shaped cross section and a scale inscribed on its face. A distinction is made between checkered and lined rods.
On one or both sides of a checkered rod there are white and black or red and white checkers 1 cm wide; divisions are marked at each decimeter, and the zero lines on the scales on both sides are offset a given distance relative to one another (Figure 1, a; BC is the plumb bob). Lined rods are used for highprecision
leveling. The front side has a channel in which an invar strip with two rows of lines 1 mm thick and 5 mm apart is stretched with a force of approximately 200 newtons (20 kilograms-force). There are divisions marked every half decimeter (Figure 1, b).