by Jim Riesterer . . . . . . . . . . Edited by Scott Hughes, Dan Narsavage & Diana Boyack
Topographic Maps Tutorial
Introduction & Materials
What is a Map?
Using Topo Maps
Map Scale
Reference Datum
Map Projections
Distortions
Grid Systems
Geographic
UTM
State Plane
Public Land Survey
Vertical Scale
Creating Profiles
Vertical Exaggeration
Calculating Slope
Using a Compass
Magnetic Declination
Get a Bearing
Go from A to B
Find Self on a Map
Topographic Maps Field Exercises
Exercise 1
Exercise 2
Exercise 3
Exercise 4
GeoSTAC Home
Field Exercises
geostac@gmail.com
April 7, 2008
Going From Point "A" to "B"
Once you’ve figured out what direction you want to go, you need to figure out how to use your compass to get you there. In the example on the previous page, you determined that the bearing between A and B is 21° (N 21°E). All you have to do now is walk a straight line from point A to point B at 21° and, after a little sweat, you’ll be at your destination.
To orient yourself along this path, orient your compass so that the north arrow is pointing at the bearing you want, but in the adjacent quadrant. For example, we want to head out at a bearing of 20° (N 20°E). To do so, align the north end of the needle with 340° (N 20°W).
When you do this, the front edge of your compass is pointing 20° in the direction you want to go.
Now perhaps it is more clear why on some compasses the east and west labels appear to be on the wrong side of the compass. If the bearing you want is N 20°E and the labels are swapped, then when you line up with N 20°E as labeled on the compass, the compass is truly pointing toward N 20°W.
Most compasses have some sort of sighting system built into them to allow greater accuracy in determining where you want to go.If your compass has a sight (check your owner’s manual to see if it has one and, if so, learn how to use it), you will orient it the same way as described above, but you can look through the sight at the same time and find an object to walk toward.
By finding an object (such as a tree or large rock) that lies along your path you will have more freedom to go around obstacles (such as large gullies, streams, hills, etc.) without losing track of the direction your are travelling. Once you reach the object you were headed for, sight in on another object along your path, repeating this process until you arrive at point B.