surveying iii (topographic and geodetic surveys) - Modern Prepper

(a) (1) Begin by completing the information in the page heading.(b)(2) Record the readings from the backsight (near) rods (keep a running total).(c) (3) Record the readings from the foresight (distant) rods (keep a running total).(d) (4) Enter the means of each set of three thread readings on the near rod and the sum of themeans. (The decimals are not usually shown when recording the mean of the three thread readings;however, they have been inserted here since millimeters and tenths of a millimeter will be used to helpdetermine the C factor.)(e) (5) Enter the thread interval on the near rod. This reading is obtained by subtracting themiddle thread reading from the upper thread reading and subtracting the lower thread reading from themiddle thread reading for each backsight.(f) (6) Enter the sum of the intervals for each backsight and the sum of all backsights.(g) (7), (8), and (9) Apply the same procedure used to obtain columnar values for thebacksights, using the readings in column (3).(h) (10) The curvature and refraction correction (Table 4-1) must be taken out and applied tothe distant-rod readings. Use each foresights separately, and determine the curvature and refractionvalue. Sum these values and apply this sum to the sum of the mean values in column (7).Table 4-1. Total Correction for Curvature and RefractionEN0593 4-14