Chinese compass

A magnetic direction-finding instrument developed in China, first used for geomancy and later adapted for navigation. Early forms used a magnetized lodestone spoon or needle to indicate direction.

Lodestone: A naturally magnetized form of the mineral magnetite. Early Chinese compasses used lodestone to align an indicator with magnetic direction.
Han dynasty: A Chinese imperial dynasty that ruled from 202 BCE to 220 CE, with an interregnum from 9 to 23 CE. Texts from the Han period describe lodestone devices associated with direction and divination.
Chinese maritime navigation: The practice of navigating Chinese vessels using observations, charts, and navigational instruments. The magnetic needle supplied direction when landmarks and celestial observations were insufficient.
Compass in medieval Europe: The adoption and development of magnetic compasses in Europe during the Middle Ages. European mariners adapted magnetic navigation after the compass spread westward from Asia.
Magnetic declination: The angle between magnetic north and geographic north at a location. The compass points toward magnetic north, which can differ from the direction of geographic north.
South-pointing chariot: A Chinese wheeled device that maintained a pointer toward the south through mechanical gearing. It indicated direction mechanically, unlike the compass's magnetic alignment.
Dead reckoning: Estimating a vessel's position by tracking its course, speed, and elapsed time from a known position. A compass provides the course component in estimates of a ship's changing position.
Age of Discovery: The period of sustained European overseas exploration from the 15th through the 17th centuries. Reliable directional instruments supported long-distance voyages across open water.
Magnetic dip: The angle at which Earth's magnetic field enters or leaves the horizontal plane. A floating needle can tilt under magnetic dip, prompting designs that kept the indicator horizontal.
Geomancy: A practice of interpreting and arranging places according to perceived forces and directional patterns. Early Chinese magnetic instruments were used to assess auspicious orientations before maritime use.

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