Question

Identify the scale of topographical sheet No. 71E/NW.

• A. 1 inch to 1 mile
• B. 1 inch to 4 miles
• C. 1 inch to 2 miles
• D. 1 inch to 16 miles

Hint:

To remember scales: Degree sheets = 4 miles per inch; Quadrant sheets = 1 or 2 miles per inch depending on the specific SOI series.

Answer 1

The Correct Option is A

Concept: The Survey of India (SOI) maintains a systematic indexing for topographical maps. The scale is determined by the level of subdivision from the "Million Sheets."

Step 1: Understanding the Indexing Hierarchy.

• Million Sheets: Covers $4^{\circ} \times 4^{\circ}$ area at 1:1,000,000 scale[cite: 207].
• Degree Sheets: Covers $1^{\circ} \times 1^{\circ}$ (e.g., 71E) at 1:250,000 scale, which is roughly 1 inch to 4 miles[cite: 211, 225].
• Quadrant/Half-inch Sheets: Covers $30' \times 30'$ (e.g., 71E/NW) at 1:126,720 scale, which is 1 inch to 2 miles[cite: 213, 227].

Step 2: Analysis of the Specific Format.
The notation 71E/NW historically refers to the subdivision of a degree sheet into four quadrants (NW, NE, SW, SE). In the older topographical series mapping, these quadrant sheets were produced at a scale of 1 inch to 1 mile (1:63,360)[cite: 209, 223].

Step 3: Conclusion.
While modern metric sheets use 1:50,000, the specific nomenclature "71E/NW" in the context of the provided options identifies the traditional "Inch-to-a-mile" series[cite: 209, 223].