Brunton Compass

What is Brunton Compass

Brunton compasses are precision instruments that have been used by explorers, scientists, and outdoor enthusiasts for over 125 years. The company was founded in 1894 by Canadian-born geologist David W. Brunton, and its first product was the Brunton Pocket Transit. This compass was designed for use in the field, and it featured a number of innovations that made it more accurate and reliable than other compasses of the time.

One of the most distinctive features of a Brunton compass is its use of magnetic induction damping. This means that the compass needle is not damped by fluid, but rather by a magnetic field. This makes the needle more sensitive and responsive, and it also eliminates the need for a liquid-filled capsule, which can be fragile and prone to leaks.

It is used to get directional degree measurements (azimuth) through use of the Earth's magnetic field.

Description of Brunton Compass Parts

 A. Long Level

 The long level for inclination measurement. For accurate inclination measurement, center the bubble in the long level using the vernier adjustment.

B. Round Level

For accurate azimuth measurement, dip direction and trend measurements, center the bubble in the round level. 

C. Iron Needle 

The needle is attached to a rare earth magnet which is induction damped, which allows the needle to seek magnetic north and come to a complete rest in a minimum amount of time, without accuracy degradation.

Brunton Compass

D. 360-degree Graduated Circle

In combination with the needle, the 1° graduated circle allows for azimuth readings that are accurate to 1/2 degree.

E – 90-degree Dip Circle

Use for measuring dip using the long level on the vernier.

F. Needle Release Mechanism- 2 Positions

Unlocked: When needle locking adjustment is unlocked the needle swings freely, even when the needle release mechanism is pressed.

Locked: When needle locking adjustment is in the locked position the needle is locked in place until the needle release mechanism is pressed

H. Rare Earth Magnet

Brunton has incorporated a cast NdFeB, rare-earth magnet which seeks magnetic north very quickly and allows for faster needle settling.

G. Vernier

The vernier is used for inclination measurements with an accuracy to 30 minutes.

J. Declination Zero Pin

The zero pin is the pointer used for magnetic declination adjustment. If no adjustment is necessary, the pin should point at 0° on the azimuth ring.

Brunton compass in the field

Uses of Brunton Compass

Measuring Angles and Bearings

Magnetic Azimuth: Determine the precise horizontal angle between true north and any object or landmark.

Vertical Angle: Measure the angle of inclination or decline, like the slope of a hill or the dip of a rock layer.

Geological Fieldwork

Strike and Dip: Accurately measure the orientation of rock layers, faults, and other geological features. This data is crucial for understanding the formation and history of rock formations.

Magnetic Declination: Determine the difference between true north and magnetic north at a specific location. This correction is essential for accurate map reading and navigation.

Land Surveying

Establishing Property Lines: Accurately measure and mark property boundaries based on bearings and distances.

Topographic Mapping: Collect data on the elevation and slope of terrain features to create detailed maps.


Mapping Site Features: Accurately record the location and orientation of archaeological artifacts and structures.

Determining Orientation of Burials: Measure the orientation of human remains to gain insights into burial practices and cultural beliefs.

Navigation and Orienteering

Accurate Backcountry Navigation: Use the compass for precise direction finding and route planning in wilderness areas. 

Sight-Seeing and Exploration: Enhance your outdoor adventures by accurately locating landmarks and points of interest.

How to Use a Brunton Compass

The Brunton compass, also known as the pocket transit compass, is a reliable and versatile tool commonly used by geologists, surveyors, and outdoor enthusiasts for navigation, orientation, and geological measurements. This compact instrument is designed to provide accurate readings of magnetic azimuths, inclination angles, and dip angles. If you're new to using a Brunton compass, here's a step-by-step guide to help you get started:

Step 1: Familiarize Yourself with the Compass

Before you begin using the Brunton compass, take some time to familiarize yourself with its parts. The main components include the sighting mirror, the compass housing, the azimuth scale, the bubble level, and the clinometer scale. Understanding how each component functions will make the usage easier.

Step 2: Adjust the Compass

For accurate readings, you need to ensure that the compass is correctly adjusted. To do this, follow these steps:

Setting the Declination: Check the local magnetic declination for your location and adjust the compass accordingly. Most Brunton compasses have a small screw or knob to set the declination.

Balancing the Needle: Hold the compass level and use the adjustment screw on the compass housing to center the magnetic needle. The needle should move freely without any friction.

Step 3: Find Your Heading (Azimuth)

Hold the Compass Correctly: With the compass open and in your hand, hold it horizontally in front of you. Keep the sighting mirror facing you.

Find a Target: Look through the sighting mirror and align the sighting line with the object or landmark you want to navigate towards.

Read the Azimuth: Once the target is aligned, note where the center of the magnetic needle points on the azimuth scale. This reading represents your magnetic azimuth.

Step 4: Measuring Inclination or Dip Angles

The Brunton compass is equipped with a clinometer scale, which allows you to measure the angle of inclination or dip of geological features such as rock formations or strata. Follow these steps to use this feature:

Hold the Compass Vertically: With the compass open and in your hand, hold it vertically in front of you, making sure the bubble level is centered.

Align the Target: Look through the sighting mirror and align the sighting line with the geological feature you want to measure.

Read the Inclination/Dip Angle: The point where the magnetic needle intersects the clinometer scale indicates the angle of inclination or dip.

Step 5: Practice and Calibration

Using a Brunton compass effectively requires practice. Start by taking readings from known landmarks to verify the accuracy of your compass. Regularly calibrate and check for any deviation in the magnetic needle to ensure reliable readings.

Step 6: Store and Care for Your Compass

After use, always store your Brunton compass in a protective case or pouch to prevent damage. Keep it away from magnetic objects, as they can interfere with the compass readings. Regularly clean the sighting mirror and compass to maintain its functionality.

In conclusion, mastering the use of a Brunton compass takes time and practice, but it is a valuable skill for anyone venturing into outdoor activities or geological studies. By following these steps and dedicating time to become familiar with the instrument, you can confidently navigate the terrain and make accurate geological measurements with your Brunton compass.

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