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Glossary of watchmaking

Longitude

Longitude | 経度/ケイド | 经度

Angle formed by the meridian of a given point, the centre of the Earth and the meridian. The longitude of a point is calculated as the difference between local time at that point and the time at the Greenwich meridian. Measured from -180° to +180°, it is negative east of Greenwich and positive west of Greenwich. Longitude is an essential factor in air and sea navigation.