What did South-Pointer / Magnetic Compass look like?

Sinan: natural lodestone ground into a spoon shape, placed on a smooth bronze diviner's plate; the handle points south. Compass: a magnetic needle floats on water or is supported on a pivot tip, surrounded by a graduated方位 dial.

How did South-Pointer / Magnetic Compass work?

Lodestone/magnetic needle in Earth's magnetic field → the needle's north pole is attracted by the geomagnetic south pole → the torque aligns the needle along the geomagnetic field direction → points north-south. The compass adds a graduated azimuth dial for reading headings.

← DiscoveriesS-Tier · Foundational

司南与罗盘

South-Pointer / Magnetic Compass

Discovery of lodestone's directive polarity → creation of the sinan (magnetic spoon) → development into the magnetic-needle compass for navigation in the Song Dynasty, providing the technological prerequisite that enabled the Age of Exploration.

司南与罗

Scientific Principle

Geomagnetic field: Earth's dipole field causes a free magnetic needle to align with the magnetic field lines. Magnetic declination: the angular deviation between geomagnetic north-south and geographic north-south.