Magnetic meridian definition: At any station, the magnetic meridian is the direction given by which condition on the magnetic needle?

Introduction / Context:
Compass bearings are referenced to the magnetic meridian, which is defined physically by the equilibrium direction of a magnetic needle at the location. However, practical instruments must eliminate biases from imbalance and local attraction to represent the true magnetic field direction.

Given Data / Assumptions:

• The needle is supported with minimal friction and correct balance for local dip.
• Nearby ferrous objects or electric currents can distort readings (local attraction).
• The desired reference is the undisturbed magnetic field direction at the station.

Concept / Approach:
The magnetic meridian is the direction assumed by a freely suspended, properly balanced magnetic needle uninfluenced by local attraction. Balancing compensates for dip so the needle remains essentially horizontal, while avoiding local attraction ensures the indicated direction aligns with Earth’s magnetic field and not with nearby stray fields or iron masses.

Step-by-Step Solution:

Verification / Alternative check:
Compass “local attraction test” compares forward and back bearings; discrepancies indicate disturbance. Removing such effects restores alignment with the magnetic meridian.

Why Other Options Are Wrong:

• Merely “freely suspended” is insufficient if the needle is unbalanced.
• Balance alone is not enough if local attraction remains.
• An iron pivot can create attraction and bias.

Common Pitfalls:
Ignoring vehicle bodies, tools, or power lines near the compass; failing to re-balance after moving long distances in latitude.

Final Answer:
A properly balanced magnetic needle that is free and uninfluenced by local attraction