57-7202-0PTRAB

Definition Transit

An instrument having two coaxial centers, one inside the other. A telescope is attached to the inner center and mounted in such a manner that it may be rotated in vertical or horizontal arcs. The outer center carries the horizontal scale. The telescope and horizontal circular scale may rotate about the same axis, independent of each other, or integrally, as a single unit. The scales are read visually by means of verniers. The instrument is usually leveled by means of four leveling screws. It is used for measuring horizontal, or horizontal and vertical angles. Excludes transit, pocket.