Why might a compass be placed in a sealed bowl with a low freezing point?

Why might a compass be placed in a sealed bowl with a low freezing point?

• A. To prevent water ingress
• B. To slow rotation in cold conditions and stabilize the compass
• C. To magnetize the needle
• D. To automatically align with true north

Answer: (B)

The main idea is damping and stability. A compass needle is a tiny magnet that freely pivots, and on a moving vessel the needle tends to sway. Filling a sealed bowl with a liquid that has a very low freezing point provides viscous damping: the fluid resists rapid motion, so the needle slows its swings and settles more quickly. The result is a steadier reading, even in cold conditions where ice or slush could otherwise interfere. This setup doesn’t magnetize the needle or automatically align it to true north; it simply stabilizes the instrument’s response. The low-freezing liquid stays liquid in cold weather, enabling consistent damping.

The main idea is damping and stability. A compass needle is a tiny magnet that freely pivots, and on a moving vessel the needle tends to sway. Filling a sealed bowl with a liquid that has a very low freezing point provides viscous damping: the fluid resists rapid motion, so the needle slows its swings and settles more quickly. The result is a steadier reading, even in cold conditions where ice or slush could otherwise interfere. This setup doesn’t magnetize the needle or automatically align it to true north; it simply stabilizes the instrument’s response. The low-freezing liquid stays liquid in cold weather, enabling consistent damping.