Because of the earth’s magnetic field.
Although Feng Shui does not mention the concept of "magnetic field", the coordination of the directions, orientations, and intervals between the circles on the compass implies the laws of "magnetic field".
The invention and application of the compass is the result of mankind's continuous exploration of the mysteries of the universe, society and life. The increasing number of circles and the increasingly complex pointer system on the compass represent the continuous accumulation of practical experience of mankind. Of course, whether these experiences are comprehensive and correct remains to be further studied, but the information marked on the compass contains a lot of ancient Chinese wisdom.
Extended information;
When it comes to "Feng Shui", people will naturally think of "Compass". When it comes to "Compass", many people will naturally think of "Compass". ". Although the compass contains the content of the compass, if the compass is equated with the compass, it will miss the mark for the application of Feng Shui.
The compass is an instrument that uses the pointing characteristics of the magnetic needle to determine direction. It has been widely used in military, navigation and other fields. In Feng Shui, to determine the orientation of the yin and yang houses and the orientation of various objects in the house, a compass must be used.
The compass, papermaking, printing, and gunpowder are collectively known as the four great inventions of ancient China. They have a long history and are said to date back to the ancient Yellow Emperor period.
When the Yellow Emperor raised troops to attack the rebellious Chiyou, Chiyou started to make moves among the troops. Suddenly, the clouds filled the air, the sky was dark and the ground was dark, and he couldn't see his fingers. The Yellow Emperor's army was trapped in the clouds and mist, and they were in chaos. Therefore, the Yellow Emperor ordered his minister Feng Hou to make a compass, imitating the characteristics of the Big Dipper's handle that always points to the north.
It is said that there is a small copper figure on top of the car. No matter which way the car turns, the arms of the small copper figure always point to the south. With the help of the compass, Huang Di's army broke out of the fog.
Baidu Encyclopedia-Compass