Brunton compas

Brunton compass

1. BRUNTON COMPASS
INTRODUCTION:-
A Brunton compass, properly known as the Brunton Pocket Transit, is a type of precision compass
made by Brunton, of Riverton, Wyoming. Unlike most modern compasses, the Brunton Pocket Transit
utilizes magnetic induction damping rather than fluid to dampen needle oscillation. Although Brunton
Inc. makes many other types of magnetic compasses, the Brunton Pocket Transit is a specialized
instrument used widely by those needing to make accurate degree and angle measurements in the field.
These people are primarily geologists, but archaeologists, environmental engineers, and surveyors also
make use of the Brunton's capabilities.


HOW TO USE:
It may be adjusted for declination angle according to ones location on the earth. Holding the compass
at waist height, the user looks down into the mirror and lines up the target, needle, and guid line that is
on the mirror. Once all three all lined up and the compass is level, the reading can be made. The strike is
measure by leveling the compass along the plane being measured. Dip is taken by laying side of the
compass perpendicular to the strikeand rotating horizontal level until the bubble is stable and reading
has been made.

2. COMPONENTS:
It has three main parts, box, slight arm, and lid. The box contains most of the elements: the needle, bulls
eye level, clinometer level, and clinometer scae, damping mechanism, lift pin, side brass skrew, and
index pin graduated circle. The needle has two ends: the north seeking end and the black south seeking
end. An aditional weight attached to south seeking end of the needleprovides proper balancing of the
needle.
APPLICATIONS & importace of brunton compass
1. Determining the magnetic declination
If the compass needle points east or west of the true north, the offset is called east or west
declination, respectively. The standard is to use the magnetic north (MN) as a reference for
declination, even in the southern hemisphere
2. Setting the declination
Geologists use the compass for mapping and measuring linear and planar objects. The
magnetic declination is set by turning the brass screw on the side of the compass box. For a
west declination of say 16
o
(i.e., declination is 16
o
west of true north), turn the card west, i.e.,
counterclockwise (by turning the screw)
3. The concept of domain
One of the objectives of studying a complexly deformed area (e.g., refolded folds) is to identify
domains (subareas) within which the fabric data of, for example, folds, lineations, foliations are
homogeneous
4. Attitude of linear and planar geological objects
Although most geologic structures are generally either curvilinear or curviplanar, they can be
approximated as either linear or planar at specific scales or domains.
5. Measuring the attitude of linear objects
Measuring trend and plunge: If the linear object is below our line of sight, open the sighting
arm and the lid, and align the open, long slot of the arm parallel to the linear feature. If the
linear feature is above our head (e.g., on a bedding above us), stand under the object and align
the linear feature with the black axial line on the mirror on the lid of the compass.