Orienteering Compass

An **orienteering compass** (protractor) is an instrument used for **navigation and orientation** that shows direction relative to the geographic directions, or points.



The magnetic compass was first invented as a device for **divination** as early as the **Chinese Han Dynasty**.



There are several kinds of compasses. The **thumb-compass** is used mostly by orienteers who just want to run fast.



The most important part of the compass is the colored arrow. We call it the **compass needle**. The red part of it is always pointing towards the **Earth's magnetic North pole**. ***A compass is designed to react to the magnetic field generated by the swirling hot mass of rock deep inside Earth***. However, there are lots of other things going on, much nearer to the compass that can throw it well and truly out of whack. The accuracy of a compass measurement in a certain situation is called **the deviation**. It's the angle between where the compass would point if it were perfectly accurate (magnetic north) and where it actually points. If there's a magnet nearby, or there are fluctuating electric currents generating magnetic fields, the compass needle is going to be affected and its accuracy is going to be reduced.