Earth's Magnetic Field

EARTH

parts of a compass are Baseplate hard, flat surface on which the rest of the compass is mounted. It has a rulers on its edges for measuring distances on maps. It's 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 base plate. You point this the way you will be traveling Magnifier for seeing small map features better 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. You hold the dial and rotate it to rotate the entire housing Declination Marks use to orient the compass in an area with known declination Orienting Arrow marked on the floor of the housing. It rotates with the housing when the dial is 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 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 Bubble a bubble of air in the housing liquid is useful for making sure you are holding the compass fairly level Mirror lets you see the compass face and distant objects at the same time. Useful for emergency signaling Sight improves aiming your compass at distant objects

compass

north only!!

the purpose