Geology

The Brunton may be adjusted for declination angle according to one's location on the Earth. It is used to get directional degree measurements (azimuth) through use of the Earth's magnetic field.

Holding the compass at waist-height, the user looks down into the mirror and lines up the target, needle, and guide line that is on the mirror. Once all three are lined up and the compass is level, the reading for that azimuth can be made.

Arguably the most frequent use for the Brunton in the field is the calculation of the strike and dip of geological features (faults, contacts, foliation, sedimentary strata, etc.).

If next to the feature, the strike is measured by leveling (with the bull's eye level) the compass along the plane being measured.

Dip is taken by laying the side of the compass perpendicular to the strike measurement and rotating horizontal level until the bubble is stable and the reading has been made.

If properly used and if field conditions allow, additional features of the compass allow users to measure such geological attributes from a distance

I suggest you get hold of a simple compass having an edge parallel to the N-S orientation (or devise it yourself). Put that edge along the dipping bed and note the reading, and find out in which quadrant the strike falls. The best way to note Strike is with reference to North(In a Brunton the  circular scale is reversed for direct reading), e.g 100 degrees N means not exactly in the East but 10 degrees more. As you know the dip of a bed is with reference to the horizontal ground. Find the maximum dip direction
by pouring some water on the dipping surface. Take a simple Level with a bubble (as with masons) and put its one end vertically against the dipping bed in line with the flow direction of the poured water, make it horizontal (parallel to the ground) and see what angle it makes with the bed. The angle between your Level and the rock surface will give the dip angle of the bed. You may not know the exact degrees of angle of dip, but for exercise purposes, note down qualitative readings as low, medium low, medium high, high etc etc. This make-shift exercise will make you understand the concept.