At some point, you might come across a compass and be expected to use it, which is why knowing what a compass is, what it is used for, and how it is used is interesting general knowledge, even if you’re not a sailor or pilot.
A magnetic compass is usually generally called a compass. A compass is a small, magnetic device used as a navigation tool, especially by geologists, mariners, and adventurers, to find their way through the woods or on water. It is an essential wilderness navigator. A magnetized compass has north and south magnetic poles.
What Is A Compass?
A compass (magnetic) is a navigation tool made of a lightweight magnet. It has a magnetized compass needle that points toward the earth’s magnetic north pole (which is also the earth’s geographic north pole) when it is under the influence of the earth’s magnetic field. The magnetic needle usually has a black and red-colored pole representing the north and south poles, respectively.
Compasses have been in use in ancient China as far back as 202 BC. Over time, its structure has been modified to be more effective and modern. To properly describe what a compass looks like, let us describe each feature of typical modern compasses.
The Baseplate
The baseplate is a flat, transparent plastic material on which the compass is embedded in the compass bowl. Sunnto compasses have a transparent base containing a map to help you measure distance. When the scale on the map and the compass are superimposed, the distance between the two points can easily be read from the compass.
The Travel Arrow
This arrow is found on the transparent baseplate. It points away from the compass. The travel arrow points in the direction you want to travel along. It is fixed and parallel to the sides of the base plate.
The Turnable Compass Dial
This is also known as compass housing. Magnetized compass dials consist of a compass card on which the magnetized needle of the compass is mounted to ensure that it can spin freely. The compass scale with 360-degree calibration is found on the dial to measure local magnetic declination.
Compass Card
This is a paper-like material used in the background of the compass (above the baseplate and inside the degree dial). It has the major cardinal directions printed on it for easy navigation.
The Orienting Arrow
The orienting arrow is a non-magnetic arrow found inside the turntable compass dial or housing. It is used to orient the compass housing or dial.
Orienting Lines
These lines within the compass housing run parallel to the orienting arrow. They are map-orienting lines that help to align your orienting arrow with actual or true north correctly.
What Is A Compass Used For?
A compass can be used to; find your heading (direction of travel), find the bearing of an object, person, or place (the direction of the object, person, or place from you), orient a map (align a map with your actual location), etc.
Kinds Of Compasses
Generally, there are two major navigational compass classifications: non-magnetic and magnetic. However, new kinds of compasses have been innovated and developed to increase effectiveness.
Modern liquid compasses are great examples. A liquid compass is a liquid-filled magnetic compass that often has a mixture of distilled alcohol and water to create a damping effect that slows the swinging of the compass needles and makes it stop faster, thereby reducing errors.
Many modern compasses also have an ordinary phosphorescent luminous paint feature that glows in the dark, making it easier to read the compass bearing when it is dark. Below are some kinds of compasses and their peculiarities.
Thumb Compass
A thumb compass is worn on the thumb like a compass ring (as its name implies). It is fast, compact, and easy to use, as it can be used as a hand-free device when worn on the thumb.
Military Lensatic Compass
A military compass is also called a lensatic compass. Military compasses allow you to take the compass reading and sight distant objects simultaneously without changing eye position. It also has a sighting wire feature for accurately finding the drawn magnetic azimuth.
The lensatic compass is quite versatile. It can be used like a standard compass to fully show North, South, East, and West directions.
Flux Gate Compass
A flux gate compass is an electronic compass that is very different from a magnetic compass. There are coils of wire made of iron, and electric currents are made to pass through, causing the core to behave like an electromagnet. This electromagnetic core senses the horizontal component of the earth’s magnetic field and digitally displays the direction of the earth’s geographical poles.
This kind of compass is usually used by mariners on the sea as it is not affected by the ship’s vessel or extreme magnetic declination variance (as in magnetic compasses) in polar regions.
Gyro compasses
Gyro compasses are non-magnetic in nature. They operate with the working principle of a gyroscope which is based on a fast-spinning disc and the rotation of the earth’s axis to find true geographic north pole.
Solar Compass or Astronomical Compass
Solar compasses are often used by surveyors to determine true north direction by reference to the position of the sun rather than the magnetic field of the earth. It does this by using the angle of the shadow cast by the sun on a compass card.
Earth or Air-Filled Induction Compasses
This kind of compass was often used in the air. It used a generator driven by the north wind to create an induction field when interacting with the earth’s magnetic poles. It is less reliable than liquid compasses, and so it fell out of use with time.
Hand or Pocket Compass
A pocket or hand compass is a portable, compact compass that can fit conveniently into the pocket. The magnetic needle, which swings freely in the direction of the magnetic north bearing of the earth, is enclosed in a non-magnetic case to prevent contact with materials that can demagnetize the compass needle.
Prismatic Compass
The prismatic compass is used by surveyors majorly for measuring magnetic bearings. It is called a prismatic compass because it consists of a prism that helps with very accurate measurements and observations.
Other kinds of compass include; fiber optic gyro compass, wrist compass, qibla, etc. Regardless of the type of compass used, a non-magnetic compass and a magnetic compass point north (magnetic north). Magnetic north is not the same as true north. The magnetic and geographic poles of the earth are miles away from each other (magnetic and true north are approximately 1,000 miles apart, depending on your geographical location).
How To Use A Compass
Place the compass flat on your palm, right in front of your chest. First, your known magnetic bearing is important to figure out where you’re headed. To do this, move your compass until the direction of the travel arrow points in the direction you’re traveling.
Turn the degree dial until the orienting arrow aligns with the north end of the magnetic needle. When this happens, you’ll be able to tell where your direction of travel is.
If you’re using a map, place the map on a flat surface with the compass on it so that the orienteering arrow points towards the geographic north on the map. Slide the compass so that its edge passes through your current position on the map.
Ensure that the orienteering arrow continues to point north. Draw a line along the compass edge through your current position on the map. If you maintain the bearing, your new path will be along the drawn line. This will align the compass’ orienteering lines with the map’s north-south pole.
Once the degree dial is in place, you can now remove the map and use the new bearing to navigate. Hold the compass horizontally in front of you with the direction of the travel arrow pointing away from you. Turn your body slightly until the north-seeking pole of the magnetic needle is aligned with the orienting needle.
You must find out the declination in the area to compensate for it on your compass. Turn the degree dial according to the number of degrees to the left or right, depending on whether the area experiences northeast or northwest declination.
