1. The Brunton Compass ©2010 Dr. B. C. Paul Note – The techniques shown in these slides are considered common knowledge to surveyors. Figures in the slides may be the authors own work or extracted from Instrument Users Manuals, Surveying by Bouchard, Mine Surveying, or various internet image sources. (Includes work done by the author in 2007)

2. The Brunton Compass or Pocket Transit  The Brunton is a small piece of low precision surveying equipment that can be put in your pocket, held in your hand, and used by one person to complete a simple survey  Distance measurement in a Brunton Survey is usually done by pacing  Bruntons have the ability to measure strikes and dips of rock formations so they are still valuable remote geological work (GPS units aren’t much use in measuring dip of a rock formation)

3. Opening A Brunton Raise the cover Extend the Sighting Arm Raise the Pointer

4. Working with a Brunton at Belly Level Look down into the mirror and line Up your target, the sighting point And the line on the mirror.

5. Reading the Brunton Use the Bubble Level to level the Compass The North Seeking end of the Compass Points to the Azimuth of the line of sight

6. Using the Brunton at Eye Level Sight through the hole in the sighting point and the hole in the mirror (it is called a peep sight)

7. The Mirror Provides a View of the Compass This time the South End Points the Azimuth

8. Taking an Incline with a Brunton Place the Brunton on the inclined surface Using the lever on the back adjust the level bubble

9. Reading the Scale Read outer incline scale and add the Vernier

10. A Quadrant – Bearing Brunton Held at Belly Level E W 30 I am going North 30 degrees East

11. A Quadrant-Bearing Compass at Eye Level EW 60 Read the South Arrow at eye Level North 60 East

12. An Azimuth Compass at the Belly 0 90270 40 Read North arrow Azimuth is 40

13. An Azimuth at Eye Level 180 270 90 40 Read the South Arrow Azimuth 40

14. Just One Little Problem  The Magnetic North Pole is not at the North Pole  This means there is a difference between true north and magnetic north  Brunton Compasses can be adjusted for magnetic declination

15. Example  The Magnetic Declination of Carbondale is 1º 31’ to the west Ie the magnetic pole is 1 degree 31’ to the west of the true north pole  If we use our Brunton with no correction for declination it will point north when in fact we are aiming 1 degree 31’ to the west

16. Checking Declination on a Brunton A pin shows the declination Set on the compass When the Pin points to 0 The declination is set to 0 There is a screw on the side Of the Brunton Compass that Rotates the scale.

17. If Our Declination were 15 degrees East of North We would rotate the Dial so the index Needle point to 15 Degrees on the east Side of north.

18. If Our Declination Were 15 Degrees West of North We would adjust so the index Needle pointed 15 degrees To the west of north.

19. Proficiency Time  Set the magnetic declination on the Brunton Compass for Carbondale Illinois.  Read the Bearing Compass at Eye Level  Read the Azimuth Compass at Belly Level

20. After Your Proficiency  So I know you can read direction on the compass  Layout a taped line of 100 feet on the sidewalk Walk the line (straight – no inebriation) and count your paces Use this exercise to establish the length of one of your paces.

21. Now Start a Brunton Traverse  Start at point A and retrace your way around the surveying stations you set up on your regular traverse.  Stand on Your Point Foresight your next point with your Brunton Note the direction of the line Pace out the distance to your foresight point and note it  Repeat for the next point until you entirely close around your traverse back to point A

22. Things to Note  I never did a Backsight Why? The compass establishes the azimuth of the foresight line  In a conventional traverse you backsight a known direction and turn an angle Backsight Azimuth + Angle = Foresight Azimuth  With the Brunton the compass gives you a direct read to the foresight without needing a backsight or measuring an angle turned.

23. Enter Your Results in the Brunton Traverse Calculator  Produce a sketch of your traverse labeling each of your points  Create a table showing the coordinates you obtained for each point by a conventional traverse and then by a Brunton Traverse