What are the shortcomings of ancient compasses? First of all, the direction of the compass needle is influenced by the earth's magnetic field, which is unevenly distributed around the world. Especially near the equator, the earth's magnetic field is generally weak, and the compass is prone to deviation. Therefore, using a compass in some geographical environments is likely to lead to the wrong direction.

Secondly, the use of ancient compasses in extreme environments is also very problematic. For example, in high latitudes, near polar regions, the compass pointer will have errors and the direction will be inaccurate. At this time, the use of the compass is very limited or even impossible. This also makes the role of compass in the ocean very limited, and it is difficult to judge the exact direction of the ship.

The last drawback of ancient compasses is that the hands are difficult to keep accurate for a long time. Compass hands need to be maintained, not only to be wiped and corrected frequently, but also to avoid getting close to large magnets and other items that will affect the compass. Moreover, the material of compass pointer is very sensitive to factors such as constant temperature, constant humidity and easy corrosion. If the compass is damaged, it will completely lose its function and cannot play its correct role. Therefore, the reliability of the compass is also greatly limited.