Engineer's Compass

Rotate the bezel until the sighting notch, sighting wire and bearing line all align, then turn yourself and the compass until the bearing line sits at your local variation, in degrees east, from the needle's north end; the sighting line then points true north.

Check for a belt buckle, wristwatch, bracelet or other iron-based object near the compass, since these can pull the needle away from the earth's magnetic pole.

It represents the millieme system, in which a circle is divided into 6400 units, and it lets you estimate lateral distances once you already know the range to an object.

Not necessarily, this is a rugged hiker's compass meant for staying oriented on a trail, not a precision instrument for exact bearings; true precision work needs a base-plate compass that aligns with map grid lines.

Line up the sighting notch and wire with the landmark, read the bearing under the bearing line through the sighting lens, then apply your local variation to convert it to a true bearing.

Magnetic north is the direction the needle actually points, toward the shifting magnetic pole in the Canadian Arctic, while true north is the fixed direction to the geographic pole; the angular gap between the two, called variation, has to be added or subtracted to convert one reading to the other.