GWSSB AAE 2015
⭕ A. Levelling
⭕ B. Bisecting
⭕ C. Centering
⭕ D. Orienting
📚 Explanation:
The U-fork and plumb bob are essential accessories used in Plane Table Surveying for the purpose of Centering.
🔹 Centering refers to placing the drawing sheet exactly over the ground station.
🔹 The U-fork holds the plumb bob which is suspended through the hole of the plane table to align it with the marked point on ground.
🔹 It ensures that the plotted point and the actual point coincide accurately, especially when starting the survey or resuming from a known point.
🔹 It is different from Orienting (aligning the direction of the table), Levelling (horizontal adjustment), or Bisecting (sighting objects).
The U-fork and plumb bob are essential accessories used in Plane Table Surveying for the purpose of Centering.
🔹 Centering refers to placing the drawing sheet exactly over the ground station.
🔹 The U-fork holds the plumb bob which is suspended through the hole of the plane table to align it with the marked point on ground.
🔹 It ensures that the plotted point and the actual point coincide accurately, especially when starting the survey or resuming from a known point.
🔹 It is different from Orienting (aligning the direction of the table), Levelling (horizontal adjustment), or Bisecting (sighting objects).
👉 Therefore, the correct answer is: C. Centering
Key Notes on U-Fork & Plumb Bob in Surveying:
- Centering ensures plotted and ground points coincide accurately
- U-fork holds the plumb bob for vertical reference
- Used before plotting begins or to resume work at same station
- Part of accessories in Plane Table Surveying
- Helps reduce instrumental errors in drawing layout
