Use of navigation

Latitude and longitude
Maps and charts often show lines of latitude and longitude, imaginary lines crossing the earth's surface. Navigation use them to help locate their position and to chart their route. Latitude is a north-south division, drawn parallel to the equator.
Maps and charts
A map is like a picture of the ground, drawn from above. It shows feature on the ground such as buildings and hills. To navigate these can be matched up with feature on the ground. Positions checked using the lines of latitude and longitude.
Light and buoys
At sea, a system of visual aids helps vessels navigate safely. Light houses and lightships send out a unique pattern of flashing signals.
Buoys are floating markers. Their shape and colour indicate different hazards, such as the edge of a shipping lane or sandbanks.
Time line
11th century - Chinese mariners use simple compasses.
14th century - The portugese develop the astrolobe. Using the sun and stars, it helps locate a position on earth.
1569 - Flemish geographer Gerardus mercator (1512-94) publishes the first world map mariners use it to navigate.
1762 - British inventor john Harrison (1693-1776) wins a prize for building a chronometer, a mariner's clock.
1930s - Scottish SRobert watson - watt (1892-1973) develops the first practical radar system. Radars used extensively in world war II.