The Magnetic Compass
Before we proceed to determine the proper compass heading to steer,
we must first learn about the workings of the magnetic compass.
To enable you to understand the principles, we will explore the
properties of magnetism.
Magnetism is a phenomenon of nature known only by its effects. It
appears as a physical force between two objects of metal, at least one of
which has been previously magnetized and has become a magnet.
A magnet is a metallic element that has the property for attracting iron
and producing a magnetic field around itself. For the purpose of
illustration, this magnetic field is usually pictured as lines of force.
Figure 2-1. Magnetic lines of force.
There are two types of magnetism: permanent and induced. A metal
bar having permanent magnetism will retain its properties when it is
removed from a magnetic field.
A metal bar having induced magnetism, however, will lose its properties
when it is removed from the same field