Definition
When a light first appears or disappears at the horizon, the observer is at its geographical range, so a single compass bearing at that instant gives a full fix. Note the eye height, look up the dipping distance table or apply 2.08 times the sum of the square roots of the heights in metres, and lay off the resulting distance along the bearing. Rise and dip the light several times by standing up and crouching to confirm the moment.
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