TRIGONOMETRIC LEVELING. Two points, A & B, are 3,134.50 From a third point, C, on the line between A the measured vertical Determine meters apart. and в, and 1,992.25 meters from A, to A is +35 28' and that to B is -15 14'. angle the allowance fraction. difference in elevation between A and B making due for the effects of curvature and atmospheric refraction