Why called "compass" and not called "compass"?

Compass is also known as a compass, because in fact, the opposite of south is north, a needle, since there is south, there must be north, there is the Earth's two poles of the magnetic force is the largest, so in the state of levitation, it will be, towards the north and south direction straighten. Here is the scientific explanation:

Introduction to the magnetic meridian

The tangent line of the magnetic meridian

The Earth's great circle cut by the horizontal geomagnetic line of divergence at a point on the ground. The magnetic needle is only affected by geomagnetism (no self-alignment) in the case of its pointing that is the direction of the magnetic meridian (that is to say, under the action of the Earth's magnetic field, the magnetic needle at a certain point of free rest when the axis of the direction of the needle). Because of the asymmetry of the geomagnetic poles and the irregularity of the magnetic field, the magnetic meridian generally does not pass through the geomagnetic north and south poles. Therefore, the direction of magnetic north pointed by the magnetic needle is not necessarily the direction of the geomagnetic north pole.

The direction of the magnetic meridian can be determined by a compass.

Passing through the center of the earth and the magnetic needle at rest indicated by the north-south direction of the perpendicular plane.

Principle of compass pointing

The Earth is a large magnetic body with a geomagnetic south pole near the geographic north pole and a geomagnetic north pole near the geographic south pole.

The compass is subject to magnetic forces in the Earth's magnetic field, so it will point north at one end of the compass.