To take a map bearing or " true bearing " ( a bearing taken in reference to true, not magnetic north ) to a destination with a protractor compass, the edge of the compass is placed on the map so that it connects the current location with the desired destination ( some sources recommend physically drawing a line ).
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A " true bearing " is measured in relation to the fixed horizontal reference plane of true north, that is, using the direction toward the geographic north pole as a reference point, while a " magnetic bearing " is measured in relation to magnetic north, that is, using the direction toward the magnetic north pole as a reference.
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Other features found on modern orienteering compasses are map and romer scales for measuring distances and plotting positions on maps, luminous markings on the face or bezels, various sighting mechanisms ( mirror, prism, etc . ) for taking bearings of distant objects with greater precision, " global " needles for use in differing hemispheres, adjustable declination for obtaining instant true bearings without resorting to arithmetic, and devices such as inclinometers for measuring gradients.
