Question

Which of the following is not associated with plane table surveying?

• A. Vernier Arm
• B. Alidade
• C. Trough compass
• D. U-frame

Hint:

Remember the accessories of a Plane Table: \[ \boxed{ \begin{aligned} \text{Alidade} &\rightarrow \text{Sighting}, \text{Trough Compass} &\rightarrow \text{Orientation}, \text{U-frame (Plumbing Fork)} &\rightarrow \text{Centering}, \text{Spirit Level} &\rightarrow \text{Levelling}. \end{aligned} } \] Mnemonic: “ATUS -- Alidade, Trough compass, U-frame, Spirit level.”

Answer 1

The Correct Option is A

Concept: The principal accessories of a plane table include the alidade, trough compass, plumbing fork (U-frame), and spirit level. A vernier arm is associated with instruments such as the theodolite and sextant, not with plane table surveying.

Step 1: Identify the plane table accessories. \[ \begin{aligned} \text{Alidade} &\rightarrow \text{Used for sighting and drawing rays}, \text{Trough Compass} &\rightarrow \text{Used for orientation}, \text{U-frame (Plumbing Fork)} &\rightarrow \text{Used for centering the table}. \end{aligned} \]

Step 2: Identify the instrument not associated with plane table surveying. \[ \boxed{\text{Vernier Arm}} \] Hence, \[ \boxed{\text{(A)}} \]