Question

Which of the following is not a component of the sight vane of a Prismatic Compass?

• A. Mirror
• B. Object vane
• C. Pivot pin
• D. Sliding frame

Hint:

Remember the important parts of a Prismatic Compass: \[ \boxed{ \begin{aligned} \text{Sight Vane} &\rightarrow \text{Mirror, Object Vane, Sliding Frame}, \text{Compass Mechanism} &\rightarrow \text{Pivot Pin, Magnetic Needle, Graduated Ring}. \end{aligned} } \] Mnemonic: “Pivot pin holds the needle, not the sight.”

Answer 1

The Correct Option is C

Concept: The sight vane of a prismatic compass consists of components such as the mirror, object vane, and sliding frame used for accurate sighting. The pivot pin is a central component of the compass mechanism that supports the magnetic needle, not a part of the sight vane.

Step 1: Examine each component. \[ \begin{aligned} A. &\ \text{Mirror} \rightarrow \text{Part of the sight vane assembly.} B. &\ \text{Object vane} \rightarrow \text{Part of the sight vane.} C. &\ \text{Pivot pin} \rightarrow \text{Supports the magnetic needle; not part of the sight vane.} D. &\ \text{Sliding frame} \rightarrow \text{Part of the sight vane assembly.} \end{aligned} \]

Step 2: Identify the component that is not part of the sight vane. \[ \boxed{\text{Pivot pin}} \] Hence, \[ \boxed{\text{(C)}} \]