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# How to Use a Compass Clinometer

Updated February 21, 2017

Compasses that do more than point north are used in several sciences, especially the earth sciences. These compasses measure the orientation of two- and three-dimensional objects. One such measurement is the dip of an object, its tilt with respect to a horizontal surface. Compasses designed to measure dip include a clinometer, a bubble level mounted on a pivot to measure inclination. Most compasses with a clinometer also have a bull's-eye level for measuring the strike, or the bearing of the intersection of a surface with a horizontal plane. This information is needed to measure the true inclination.

Place the long, straight side of the compass along the tilt of the line.

Rotate the frame of the clinometer until the bubble is precisely centred in the level. On some models, a weighted disk rotates when the compass tilts, so you do not need to turn the clinometer by hand.

Read the angle of inclination where the pointer on the clinometer meets the scale printed on the compass housing.

Measure the strike of the surface. Inclination measured at any angle other than perpendicular to the strike is incorrect. Place the bottom edge of the straight side of the compass on the surface, and rotate the compass until the bubble is centred in the bull's eye.

Draw a pencil line on the surface using the edge as a guide. Measure the inclination of the surface at right angles to this line.

Place the long, straight side of the compass along the tilt of the line.

Rotate the frame of the clinometer until the bubble is precisely centred in the level. On some models, a weighted disk rotates when the compass tilts, so you do not need to turn the clinometer by hand.

Read the angle of inclination where the pointer on the clinometer meets the scale printed on the compass housing.

#### Tip

If a compass has a clinometer but not a bull's-eye level, take several measurements of a three-dimensional object's tilt using the clinometer. The steepest measured inclination is closest to the true inclination.