A typical orienteering compass will be rectangular in shape and be approximately 2-by-4 inches in size. The base plate of the unit will be made of clear plastic and marked along the sides with ruler increments. There will also be a direction of travel arrow printed on the center of the base plate which is used for course plotting. There will also be a small magnification window for reading fine print and is also handy for starting fires in a survival situation. There is also an index pointer at the base of the compass that aligns with the direction of travel arrow and ends at the edge of the compass heading dial for determining degree headings.
The housing is the raised portion of the compass which contains the direction needle and is filled with liquid. The needle is a magnetized piece of metal with one end painted red to indicate north. The needle rests on a small point which allows for unrestricted free movement. The bubble of air is left as an aid in leveling. The compass should be held so that the bubble is centered over the center point of the needle where it rotates. Underneath the bubble may be orienting lines that are used to align the compass to lines on a map. This will usually be a starting reference point for reading a map.
This is the needle inside the movable compass housing that is always pointing magnetically north. Located beneath the magnetic needle, the orinting arrow rotates to align with the magnetic needle in order to orient and establish a bearing.
Other Compass Features
Other types of compasses may have features that aid in orienteering. A sighting window allows the user to hold the compass at eye level and get a visual fix on a distant object. A mirror may also be featured on some models which you to see reference an object and see the heading at the same time. The mirror is also useful as a signaling device in an emergency situation.
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