HIST363: Global Perspectives on Industrialization

Diagram of a Ming dynasty mariner's compass

The compass in the Four Great Inventions was formerly the compass of ancient China. It is a kind of direction-indicating tool, which is widely used in navigation, field exploration and other fields. In ancient times, it had a profound influence on trade, war and cultural exchange.

The compass's origins may be traced back to the Warring States Period (476–221 BC), when Chinese people utilized a device known as a si nan to point in the right direction.

During the early Song Dynasty, a spherical compass with a small needle made of magnetic steel was created after steady development. The little needle has one end pointing south and the other pointing north. During the Northern Song dynasty (960–1127), the compass was brought to the Arab world and Europe.

People relied on interpreting the positions of the sun, moon, and pole stars to tell directions on open ocean or new area before the discovery of the compass. When the weather was gloomy or severe, traveling was difficult.

A lodestone compass was used in China during the Han Dynasty between the 2nd century BC and 1st century AD, where it was called the "south-governor" (sīnán 司南). The earliest reference to a magnetic device used for navigation is in a Song Dynasty book dated to 1040-1044, where there is a description of an iron "south-pointing fish" floating in a bowl of water, aligning itself to the south. The device is recommended as a means of orientation "in the obscurity of the night". The first suspended magnetic needle compass was written of by Shen Kuo in his book of 1088.

According to Needham, the Chinese in the Song Dynasty and continuing Yuan Dynasty did make use of a dry compass.

The dry compass used in China was a dry suspension compass, a wooden frame crafted in the shape of a turtle hung upside down by a board, with the lodestone sealed in by wax, and if rotated, the needle at the tail would always point in the northern cardinal direction. Although the 14th-century European compass-card in box frame and dry pivot needle was adopted in China after its use was taken by Japanese pirates in the 16th century (who had in turn learned of it from Europeans), the Chinese design of the suspended dry compass persisted in use well into the 18th century.

People could readily locate a direction when sailing on large oceans and exploring new area with the creation of the round compass, which led to the discovery of the New World and the development of sailing ships.