The compass is the most common and simplest tool for measuring direction. In its basic form, it consists of a magnetized needle mounted on a jewel that allows free swinging of the needle.
The magnetized needle has a north pole and a south pole. When allowed to swing free, the south pole of the magnetized needle is attracted to the magnetic north pole of the earth. Thus, the needle is pointing towards magnetic north (as opposed to the north pole, more of this in maps).
It would be very inconvenient to continually hold the jewel needle combination, so it is mounted inside a sealed bezel. This bezel may or may not be "liquid filled." The bezel is then mounted on some sort of case to allow easy operation of the compass and protect it from damage.
There are several designs of compasses. In my opinion, the best compass design for use in treasure hunting and other outdoor activities is the "lensatic compass."
The Miliary Lensatic Compass
This compass was designed for the military and is still in use today.
Lensatic Compasses you can buy now from
The lensatic compass is easy to operate, allows accurate measurements, can be used while moving, and folds up into its own protective case. If you purchase one of these, don't get the cheap ones. The are usually of poor quality and easily damaged. Typical price would be about $40.00 or so. The investment is well worth it.
Another type of compass that is widely used is the standard flat compass. It has a bezel mounted on a clear plastic base. This type of compass is used for "orienteering" (a recreation of moving from point to point cross country). Although this compass is sufficient for this, it is not very accurate for taking measurements of direction to distant points.
Flat "Orienteering" Compass
Orienteering Compasses you can buy now from
There are some modifications available for the flat compass, such as a protective cover, mirror, and other little improvements.
But for my money, I prefer the lensatic.