The compass, also known as the compass, is a simple instrument used to determine the position. The main component is a magnetic needle mounted on the shaft. The magnetic needle can rotate freely under the action of the natural magnetic field and maintain the tangential direction of the magnetic meridian. The north pole of the magnetic needle points to the geographical north pole. This performance can be used to distinguish the direction. Commonly used in navigation, geodetic, travel and military. The invention of the compass that physically indicates the direction consists of a trilogy: Sinan, magnetic needle and compass. They belong to the invention of China.
The compass is the common name of the folk. In the military, the official name is the compass or the military compass. The geological use is called the geological compass.