The Parts of a Compass

The Parts of a Compass 

• Baseplate: hard, flat surface on which the rest of the compass is mounted. It has a ruler on its edges for measuring distances on maps. Its edge is straight and useful for laying lines on a map.

• Scales: each edge of a compass may have different rulers for use with different map scales.

• Direction of Travel Arrow: marked on the baseplate. You point this the way you will be traveling, always away from you.

• Index Pointer: butt end of the direction-of-travel arrow. It ends right at the edge of the dial and is where you take degree readings.

• Dial: ring around the housing that has degree markings engraved. Because the dial is a circle, it has 360 degrees. You hold the dial and rotate it to rotate the entire housing.

• Orienting Arrow: marked on the floor of the housing. It rotates with the housing when the dial turned. You use it to orient a compass to a map.

• Orienting Lines: series of parallel lines marked on the floor of the housing and on the base plate.

• Magnetic Needle: magnetized piece of metal that has one end painted red to indicate North. It sits on a fine point that is nearly frictionless so it rotates freely when the compass is held fairly level and steady.

• Housing: main part of the compass. It is a round plastic container filled with liquid and has the compass needle inside.