Compass

A compass is a tool that shows the main directions used for finding your way. It usually has a needle that points to magnetic north. Other tools like magnetometers and GPS can also help with direction.

Compasses show angles in degrees. North is 0°, and the numbers go up as you move clockwise. East is at 90°, south at 180°, and west at 270°. These numbers help show directions.

The magnetic compass was first made a long time ago in China during the Han dynasty. It was later used for travel during the Song dynasty. People in Western Europe and the Islamic world started using it around the year 1190. The compass helps people find their way by pointing north, so it is very useful for anyone traveling to new places.

History

Main article: History of the compass

The compass has a long and interesting history. The ancient Greek philosopher Thales of Miletus noticed that a special stone called lodestone could pull iron towards it.

In ancient China, people used lodestone to make devices that pointed north. By 1088, Chinese inventors created compasses using iron needles that were magnetized with lodestone. These compasses helped people find their way during journeys. Over time, compasses spread to Medieval Europe and the Islamic world, where they became important tools for sailors and explorers.

Design

Most compasses have a tiny magnet that acts like a needle. It floats in liquid so it can move easily. This helps the compass point north steadily. Some compasses glow in the dark so you can see them at night. Many also have tools to help measure angles and directions on maps.

Some special compasses, like those used by soldiers, have a round card instead of a needle. They also have sights to help aim. These compasses work well almost everywhere. But compasses can sometimes get confused by metal or electronic devices nearby, which can make them point the wrong way.

Variants

A thumb compass is often used in orienteering, a sport that involves reading maps and understanding the land. These compasses usually have few degree markings and are mainly used to line up maps to magnetic north. They often have a large needle to make it easier to see and may be transparent so you can look at a map through the compass.

Other types of compasses include the earth inductor compass, which uses principles of electromagnetic induction and the Earth's magnetic field. Small electronic compasses, known as eCompasses, are found in mobile phones and other devices. These use tiny sensors to detect the Earth's magnetic field and help find direction.

Specialty compasses include the Qibla compass used by Muslims to find the direction to Mecca, the prismatic compass used by surveyors and explorers for very accurate readings, the trough compass used for land surveying in the past, and the luopan used in feng shui practices.

Construction

To make a compass, you need a magnetized rod. You can magnetize a rod by rubbing it with a natural magnet called a lodestone. The rod is placed so it can move freely, letting it point toward magnetic north. Early compasses were simple, using a magnetized needle floating in water.

Over time, compasses got more advanced and now have a dial marked with directions. Most compasses today use a 360-degree system, where the circle around the compass is split into 360 equal parts. Some places use different systems, like dividing the circle into 400 parts called grads. Compasses need to be balanced to work well in different places. They can be affected by metal and electricity, so it's best to use them away from cars, trucks, and other metal objects.

Use

A magnetic compass points toward magnetic north. This is not exactly the same as the true geographic North Pole. By knowing this difference and making small changes, people can use a compass to find their way correctly.

When using a compass with a map, you can line up the compass with the map to see the direction to a place. It’s important to keep the compass on a flat surface and away from magnets or electronic devices. These can change how the compass works.

Non-magnetic compasses

Besides magnetic compasses, there are other ways to find north for navigation. Two important types are the gyrocompass and GPS compass.

A gyrocompass uses a fast-spinning wheel to find true north, the direction of Earth’s rotation. It is not affected by metal on ships. Large ships often use gyrocompasses. Smaller boats may use electronic compasses or still rely on traditional magnetic compasses.

GPS receivers can also determine direction very accurately by knowing their position on Earth. They find true north and are not disturbed by magnetic fields. They need to communicate with satellites in space to work.