A Note on the Variation of the Lateral Refraction at Night

Abstract

By examing the night observations of the first order triangulation, it was found that the difference between the values of any angle obtained by observing it at two different times t and t+τ(τ<20 minutes) seemed to belong to a normal distribution with its stan dard deviation proportional to the square root of the time interval (τ), independent of the angle orientation and of the initial time t.