Compass

Pictured: A lensatic compass.

The compass has been a standard navigational tool since it was introduced in 206 BC. These devices help you orient yourself when navigating, either with or without the aid of a map. They work by having a magnetized needle, connected to a post holding it in place above a directional base plate with the directional markings. The needle moves to align with the Earth's magnetic north, and south.

The design of the modern magnetic compass differs slightly from the very early versions. Back then, a magnetized needle was attached to a lightweight piece of wood or cork and it would float in a shallow dish of water to allow the needle to move into pointing in the direction of north/south.

Unlike the GPS in your phone or car, a compass will still work without electricity or satellites.

A lensatic compass allows easy sighting across vast distances.

There are many subtypes of compass, but here we will focus on the lensatic compass, which is the kind commonly used by military personnel. As such, they are universally understood and easy to find. This type of compass can offer you a choice of whether you want one designed for specifically the northern, or southern hemisphere. The various lensatic models typically come with a glow-in-the-dark tritium or phosphorescent needles. They also allow for reading the actual bearings, the degrees of one's current position.

The coolest thing about these is that they also have a sighting wire; a feature not present in many other compasses. This lets the user simply look through it to figure their direction, or use it in conjunction with a map.

There's a handy Youtube video for introduction to the Lensatic Compass, it's design and directions for use:

http://www.youtube.com/watch?v=FI7C8VlbYfI