We always need to tell directions, but quite often, we have no idea how to do so. That's when we need something to help with direction-finding, and a compass is one of the simplest and most convenient options. Whether it's for wilderness survival, outdoor activities (like traveling, hiking, or trekking), or even navigating in big cities, having a compass can bring great convenience to your movements. It's also one of the most effective and straightforward ways to prevent outdoor enthusiasts from getting lost in the wild.
Introduction to the Compass
A compass is a simple instrument for determining directions, also known as a "north-pointing needle." Its predecessor is the sinan, one of the Four Great Inventions of ancient China. The main component is a magnetic needle mounted on an axis, which can rotate freely. Under the influence of the Earth's magnetic field, the needle stays aligned with the tangent of the magnetic meridian. Since the north pole of the needle points to the geographical North Pole, this property allows it to help determine directions. Compasses are widely used in navigation, geodetic surveying, travel, and military affairs, among other fields.
How to Use a Compass
There are many types of compasses; some military-grade ones even integrate functions like magnetic declination measurement, altitude measurement, and distance calculation. Thus, it's impossible to cover all usage methods here. For specific instructions, refer to the user manual. Below is a guide to the basic functions of a compass.
Before using it correctly, ensure the following two points:
The compass must be placed or held horizontally.
Avoid interference. Keep the compass away from magnetically conductive metals (such as iron, nickel, and other metals that magnets can attract) and objects that may interfere with it, including mobile phones, cars, airplanes, and high-voltage lines.
Most compasses are marked with directions: east, west, south, north, southeast, southwest, northeast, and northwest. While Chinese labels exist, English markings are more common: E (east), S (south), W (west), N (north) for the four cardinal directions, and SE (southeast), NE (northeast), SW (southwest), NW (northwest) for the intermediate directions.
To use it: Rotate the compass so that the arrow pointing "north" aligns with the letter N (they should point in the same direction). At this point, the directions corresponding to the other letters on the compass will match the actual geographical directions.
Main Functions of a Compass
Direction determination:
Identifying east, south, west, and north.
Calibrating map orientation.
Measuring magnetic azimuth angles.
Distance measurement:
Directly measuring on-map distances with a surveying ruler.
Reading on-map distances using an odometer.
Roughly determining the distance from your location to a target with a distance estimator.
Calculating marching time and speed: Using the speed-time table on the instrument, you can determine the time required for a march or the marching speed within a specified time while measuring distance.
Measuring slope gradient (pitch angle):
Open the instrument, position the reflective mirror at a roughly 45-degree angle to the dial base, and hold the instrument sideways. Aim along the sight and front sight at the edge of the slope, keeping the line of sight parallel to the slope. Let the angle gauge swing freely; the scale indicated by the central line of the angle gauge on the pitch angle table (visible in the reflective mirror) is the desired pitch angle (slope). This function can be used to roughly measure the downward tilt angle of antennas in wireless communication systems.
Precautions for Using a Compass
Use it horizontally to ensure accuracy.
Keep it away from wire mesh and magnetic objects (e.g., high-voltage lines, generators, speakers, magnets) to avoid disrupting the magnetic needle.
Do not knock or tap the compass, as this may affect measurement accuracy.
Keep the casing and mirror clean; avoid wiping them with dirty cloths or hands.
When not in use, store it in its case and keep it away from ferromagnetic materials to prevent loss of magnetism.
When choosing a compass, consider factors like brand reputation, functional diversity, accuracy, portability, and durability. Refer to user reviews and experiences to make an informed decision. Regardless of the brand, proper maintenance and usage will ensure long-term stability and accuracy.
