
RT System 2 v2.3
184
Deployment Guide R01.i
© 2010-2014 Wireless Seismic, Inc. All rights reserved.
F
F.
Using a Compass
This chapter describes how to use a sighting compass. A sighting compass has the same
features as a baseplate compass, but adds a vertical mirror that allows you to view the
compass dial and the landmark at the same time.
For a in-depth descriptions of using a compass with a map and setting the declination on
a compass see the following links:
i
http://www.compassdude.com/default.shtml
i
http://www.compassdude.com/compass-declination.shtml
i
http://www.rei.com/learn/expert-advice/navigation-basics.html
i
http://www.thecompassstore.com/howtouseyour.html
A compass needle points to the magnetic north pole which is not the same as true or
geographic north. The difference between magnetic and true north is called magnetic
declination. The declination value depends on your actual location on the Earth. Over
time, as the Earth’s magnetic field shifts, the declination values also shift.
Maps are drawn with true north at the top edge. When using a compass to navigate or
locate objects, you must adjust the readings to account for the angular difference
between true north (
ღ
) and magnetic north (MN). The declination value is marked on
topographical maps as shown in the following figure:
Figure F–1 Sighting Compass (70-0067)