Classes are back in session, and we’re back to normal episodes. Join us to talk about Brunton pocket transits, argue about strike and dip, and discuss the zombie apocalypse.
What is a Brunton?
- A compass, but a really expensive one with lots of features
- Generally referring to the conventional pocket transit
- About the size of a deck of cards, but worth $500
- It’s a very accurate compass/clinometer combination that we use to take strike and dip measurements amongst others
- Can also sight bearings to objections or angle from horizontal by using the sights and mirror
- Can set the magnetic declination. Just don’t forget!
Strike and Dip
- Two numbers that define the orientation of a plane in 3-dimensional space using an agreed upon handedness convention
- Dip direction is the direction water would run if poured on the rock, angle is how steep that rock is inclined to horizontal.
- Strike is 90 degrees to dip, but conventions are mixed and messy
Azimuth vs. Quadrant
- Compasses are available in two formats.
- This has started holy-wars
History of the Brunton
- Pocket transit invented by David W. Brunton (1849–1927) and patented in 1894
- He was a Canadian mining engineer that was tired of carrying heavy survey equipment… any of us can relate
- Neat photo of early Brunton
- A bunch of businessmen in WY bought it and started Brunton Inc. in Riverton. (1972)
- Silva of Sweden
- Fiskars (Finnish company)
- Needs to have the needle weighted when at very high magnetic dip angles.
- Cheap knock-off compasses are everywhere
- Changed the way the needle is balanced, and oftentimes it comes unscrewed with no way to fix it. This was a change in manufacturing that many people are unhappy about.
Fun Paper Friday
Zombies! This week we learn about mathematical modeling of zombie disease spread an how it relates to real world problems… mainly politics.
Munz, P., Hudea, I., Imad, J., & Smith, R. J. (2009). When zombies attack!: mathematical modelling of an outbreak of zombie infection. Infectious Disease Modelling Research Progress, 4, 133–150.
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John Leeman - www.johnrleeman.com - @geo_leeman
Shannon Dulin - @ShannonDulin