Initially the compass was made out of metals which makes the unit very expensive. Recently the Brunton company produce two different versions of their models; one with the original metal body and another with high density plastic. I personally prefer the original unit because I like the weight and feel of it. However, both versions will provide the same results and both versions comes with exact same layout.
Before start using anything, we need to learn the layout and features of the device. The compass has a hexagonal shape to it’s outside perimeter creating flat perfectly straight surfaces. This is not for aesthetic appeal. The flat surfaces, specially on each side, provide the support for measuring angles of inclines and angles of strike of Geologic features. The base casing has an arm mounted to the body for directional measurements. Even the cover (lid) of the unit has a mirror which function as a sight taking tool. Everything on the Brunton Compass is a tool.
Features of the Pocket Transit Compass
Above image is a picture of typical Brunton Pocket Transit Compass model used by universities and professionals. A list of key components on the base casing can be summarized;
A – Long Level – Used to take azimuth measurements of strike.
B – Circular Level – Used to take angle measurements of dip.
C – Iron Needle – Points to magnetic North and it is damped using the magnet below the pivot point. But the bearing can be adjusted accordingly by rotating the declination zero pin.
D – ۳۶۰-degree Graduated Circle – Used for azimuth readings that are accurate to half of a degree.
E – ۹۰-degree Dip Circle – Used for measuring dip using the long level on the vernier.
F – Needle Pin – Helps to lock the needle in place in order to take a reading.
G – Vernier – The vernier is used for inclination measurements with an accuracy to 30 minutes.
H – Rare Earth Magnet – A cast NdFe magnet which allow the iron needle to seek North accurately and quickly. It also reduces the magnetic interferences from the nearby environment.
J – Declination Zero Pin – An arm behind the compass is used to move the pin. Using tabulated data on magnetic declination, the degree of correction is set.