magnetic compass

Instrument for finding directions; it has a graduated compass card and a magnetic needle that points toward magnetic north.

base plate

Transparent surface that supports the compass card and has markings and scales.

baseline

Line marked on the base plate that is placed on top of a topographic map; it shows the direction of the place toward which the person wishes to travel.

scale

Graduated line used to judge the distance to be traveled on a topographic map, in conjunction with the map’s scale.

pivot

Point around which the magnetic needle moves.

magnetic needle

Pointer with a red magnetized part that points to Earth’s magnetic north pole.

sighting line

Line running parallel to the baselines; it is used to indicate the direction of travel.

sight

Device used to select a landmark in the direction a person chooses to walk.

graduated dial

Each of the equal intervals marked on the dial that indicate the angle in degrees of the points on the compass card.

compass card

Rotating device that is graduated in degrees and marked with the four cardinal points; it is used to indicate the direction of travel with respect to true north.

compass meridian line

Line that, when matched with the meridian line on a map, can be used to determine the direction of travel in degrees.

edge

Compass card marks where the needle’s red dot comes to rest when the compass is aligned with magnetic north.

cover

Compartment that contains the mirror and protects the compass card when it is folded over the base plate.

sighting mirror

Polished glass surface that reflects the image of the compass card and confirms the direction of travel.