Fortunately for travelers, the earth behaves as if it were a gigantic magnet. From natural magnetic rock called 'lodestone', early mariners made a compass that enabled them to find the direction of magnetic north. Still today compasses have a magnet. One end always turns towards magnetic north. So, wherever you are, you can use a compass tell the direction.
A compass on a map (also called a compass rose),
like a real compass, shows the direction. Most arrows show north
on the map but there are exceptions. By tradition maps are drawn
so north is at the top of the page. Some cartographers in New
Zealand and Australia dislike this arrangement as it shows these
countries to be at "the bottom" of the world. They make
their maps with south at the top of the map sheet. In olden times,
the compass rose was an opportunity for the cartographer to show
their artistic skill. Thus, on ancient maps, the compass rose
is often quite decorative. It's also useful to fill the empty
spaces on the map.
The one shown above is from a world map made in 1375 (the Galapagos
had not been discovered!). On modern maps the designs are less
elaborate since the cartographer aims for clarity.
