Transit instrument Meaning, Definition & Usage

  1. noun a telescope mounted on an axis running east and west and used to time the transit of a celestial body across the meridian

WordNet

Definitions
  1. . (Astron.) (a) A telescope mounted at right angles to a horizontal axis, on which it revolves with its line of collimation in the plane of the meridian, used in connection with a clock for observing the time of transit of a heavenly body over the meridian of a place. (b) (Surv.) A surveyor's transit. See Transit, 5, above.

Webster 1913