Magnetic declination
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Magnetic declination is the angle between magnetic north and true north at a particular location on the Earth's surface. The angle can change over time due to polar wandering.
Western Long Island Sound, 1884
Western Long Island Sound, 2008
Baseplate compass adjusted for 10° west (negative) declination and a true north direction of travel
Compass
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A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It typically consists of a magnetized needle or another element, such as a compass card or comp
Magnetic declination
…on the Earth's surface. The angle can change over time due to polar wandering. Magnetic north is the direction that the north end of a magnetised compass needle points, which corresponds to the direction of the Earth's magnetic field lines. True north is the direction along a meridian towards the geographic…
A modern military compass, with included sight device for aligning
Model of a lodestone compass from Han dynasty
A liquid-filled protractor or orienteering compass with lanyard
Cammenga air filled lensatic compass