Column 1. Record the station number of each post set. This includes the stationing of all
terminal end posts, intermediate posts, setups, setbacks, and broken grades.
Column 2. Record all backsight shots with the reading from the meter side of the rod. A
backsight reading indicates a change of position for the instrument. Try to balance the length
of all backsights and foresights to reduce errors introduced by curvature and refraction.
Column 3. Record the meter rod readings on all posts set on the baseline. Notice that
readings are to the nearest 0.001 of a meter. Make the numbers clear and legible.
Column 4. The value for each entry in this column is the difference between successive rod
readings. For example, at station 4 the rod reading was 1.309 meters and at station 3 it was
1.540 meters. Therefore, the entry in column 4, opposite station 4 is 1.540 - 1.309, or 0.231.
Since station 4 is higher than station 3 (indicated by a smaller rod reading at station 4), record
it as 0.231.
Column 5. In the remarks section, list the name, rank, and position of each individual in the
survey party. Also, add any other information pertinent to the survey, such as unusual wind
conditions and temperature variations. The observer should initial the field notes after he has
checked the recorder's figures.
Column 6. Record all backsight shots from the reading on the foot side of the rod. Add this
reading to the elevation of the known benchmark to establish the height of instrument (HI).
You must know the HI in order to calculate the elevations of the posts set on the baseline (if
available).
Column 7. Record the foot rod readings on all posts on the baseline. Notice that the readings
are rounded to the closest 0.001 of a foot.
Column 8. The value for each entry in this column is the difference between successive rod
readings. For example, at station 4 the rod reading was 4.290 feet and at station 3 it was
5.052 feet. Therefore, the entry in column 8, opposite station 4, is 5.052 - 4.290, or 0.762.
Since station 4 is higher than station 3 (indicated by a smaller rod reading at station 4), record
it as +0.762.
Column 9. Take the difference in elevation in feet (column 8) and convert this figure to
meters. This is done so that all figures in the final computation of the mean difference
between the two runnings will be in the same unit of measure.
Column 10. To obtain this value, take the entry in column 4 and column 9 and find their
mean difference. For example, taken from station 4:
EN0593
3-10
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