In this case, you know the "aspect," but you don't know the number of degrees.
using a compass without adjustable declination, make sure the direction of travel of arrow is pointing directly away from you. Now rotate the compass dial until the red magnetic needle overlays the orienting arrow. Observe the reading at the index line. If local magnetic declination is positive, then add the necessary amount. If the local declination is negative, then subtract the necessary amount. The number at the index line after adding or subtracting is the true direction you are facing.
If using a compass with adjustable declination, make sure the direction of travel arrow is pointing directly away from you. If you haven’t done so already, adjust the declination so the orienting arrow deviates from the compass ring’s north indicator by the amount & direction of local magnetic declination. Turn the compass dial until the red magnetic needle overlays the orienting arrow. The number at the index line is the true direction you are facing.
