Hand compass

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Parts of a hand compass

A sighting compass or hand compass is a navigational device used to determine direction on the Earth while allowing for sighting a target and viewing your bearing at the same time. Hand compasses are useful tools for map reading, scale calculations, orienting, as well as other objectives. A few advantages of a hand compass over a traditional compass is that it can serve multiple uses and is very mobile.

[edit] Parts of a hand compass

The baseplate is a hard flat surface on which the rest of the compass is mounted. It usually has straight sides with rulers on the sides. This makes for easy distance measurements on maps, and the ability to draw straight lines on maps. A hand compass typically has scales on it edges which vary according with different rulers. A very basic part to any compass is the housing. The housing is the main part of a compass and is the round plastic piece that is filled with liquid and has the needle inside of it. The needle sits on a point and rotates freely when the compass is held somewhat level and steady. The needle is made of a magnetic metal and is red in color to indicate the direction north. On the outside of the housing is the dial. The dial is a ring around the housing with declination marks on it, usually in two degree increments. The peep sight is used for viewing a desired target while viewing an azimuth with the mirror. The dial can be rotated to turn the housing. On the floor of the housing is an orienting arrow. This arrow rotates with the housing when the dial is turned. Orienting lines are a set of lines marked on either floor of the housing, or baseplate and sometimes both ^[1].

[edit] Uses

How a hand compass is used

Hand compasses are widely used in the practice of forestry. Most foresters use a hand compass or one similar to the one above. By using a compass in combination with aerial photographs and maps a person can determine his/her location in the forest, determine which direction they need to go, estimate distance, estimate area, and find points of interest (marked boundary lines, USGS marker, plot centers).

Anyone moving from one location to another can keep a straight line by holding the compass an arms length away and at eye level. They can view their azimuth by adjusting the mirror and using the peep sight to view a target (a particular tree, rock, or other object) along this azimuth and then lower the compass and begin pacing towards it. The process is repeated until you reach a predetermined destination.