Difficulty: Easy
Correct Answer: Establishing intermediate points in straight line between terminal stations
Explanation:
Introduction / Context:To measure a straight distance accurately with a chain or tape, the line between the two terminal stations must be clearly defined and kept straight. Ranging is the process used to align and mark intermediate points so that measurement proceeds along the intended straight line without lateral deviation.
Given Data / Assumptions:
Concept / Approach:In direct ranging, the observer aligns an intermediate rod so that it lies visually on the straight line joining the two terminals; in indirect ranging (hilly/obstructed terrain), reciprocal or step-by-step methods are used. Once intermediate points are fixed, chaining proceeds accurately along the straight line through these points.
Step-by-Step Solution:
Place ranging rods at the two terminal stations.Move the intermediate rod until it lines up with both terminal rods as seen from one end (or by reciprocal signals).Fix the intermediate point with a peg; repeat for additional points as necessary.Carry out chaining along the ranged line through these fixed points.Verification / Alternative check:Re-check alignment from the opposite terminal; small deviations appear as apparent lateral offsets of the intermediate rod, prompting fine corrections.
Why Other Options Are Wrong:
Common Pitfalls:Parallax due to not sighting with one eye; using bent or poorly painted rods; failing to check alignment from both ends.
Final Answer:Establishing intermediate points in straight line between terminal stations
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