This is the important lesson, and you should learn
it well.
It's when you use both compass and map the compass is really good,
and you will be able to navigate safely and accurately in terrain you've never
been before without following trails. But it'll take some training and
experience, though.
I am not covering map reading here, guess you would have to consult other sources for that, but the lesson will be useful if you have a sense of what a map says.
First, a quick summary of what you will learn in this lesson:
Here is our compass again:

The principles are much the same as in lesson 1 but this time, you are using the map to tell you which way is correct instead of your intuition.
Take a map. In our first example, we look at a map made for
orienteering, and it is very detailed. Well, not really. We look at a fictitious
map I drew myself, but never mind. To the point.
You want to go
from the trail-crossing at A, to the rock at
B. Of course, to use this method successfully, you'll have to
know you really are at A.
What you do, is that you put your compass on
the map so that the edge of the compass is at A. The edge you must be using, is
the edge that is parallel to the direction of travel arrow. And then, put B
somewhere along the same edge, like it is on the drawing. Of course, you could
use the direction arrow itself, or one of the parallel lines, but usually, it's
more convenient to use the edge. At this point, some instructors say that you
should use a pencil and draw a line along your course. I would recommend against
it. First, it takes a lot of time, but offers no enhancement in accuracy of the
method. Second, if you have wet weather, it may destroy your map, or if it is
windy, you may loose it. You should keep your map (preferably in a sealed)
transparent plastic bag, and if it is windy, tied up, so it can't blow away. But
most important is that any drawings may hide important details on the map.
Time to
be careful again! The edge of the compass, or rather the
direction arrow, must point from A
to B! And again, if you do t his wrong, you'll walk
off in the exact opposite direction of what you want. So take a second
look. Beginners often make this mistake as well.
Keep
the compass steady on the map. What you are going to do next is that you are
going to align the orienting lines and the orienting arrow with the meridian
lines of the map. The lines on the map going north, that is. While you have the
edge of the compass carefully aligned from A to B, turn the compass housing so
that the orienting lines in the compass housing are aligned with the meridian
lines on the map. During this process, you don't mind what happens to the
compass needle.
There are a
number of serious mistakes that can be made here. Let's take the problem with
going in the opposite direction first. Be absolutely certain
that you know where north is on the map, and be sure that the orienting arrow is
pointing towards the north on the map. Normally, north will be up on the
map. The possible mistake is to let the orienting arrow point towards the
south on the map.
And then, keep an eye on the the edge of the compass. If
the edge isn't going along the line from A to B when you have finished turning
the compass housing, you will have an error in your direction, and it can take
you off your course.
When you are sure you have the compass housing right, you may take
the compass away from the map. And now, you can in fact read the azimuth off the
housing, from where the housing meets the direction arrow.
Be sure
that the housing doesn't turn, before you reach your target B!
The
final step is similar to what you did in lesson 1.
Hold the compass in your hand. And now you'll have to hold it quite
flat, so that the compass needle can turn. Then turn yourself, your hand, the
entire compass, just make sure the compass housing doesn't turn, and turn it
until the compass needle is aligned with the lines inside the compass
housing.
The mistake is
again to let the compass needle point towards the south. The red part of the
compass needle must point at north in the compass housing, or you'll go
in the opposite direction.
It's time to walk off. But to do that with optimal accuracy,
you'll have to do that in a special way as well.
Hold the compass in your
hand, with the needle well aligned with the orienting arrow.
Then aim, as careful as you can, in the direction the direction of
travel-arrow is pointing. Fix your eye on some special feature in the terrain as
far as you can see in the direction. Then go there. Be sure as you go that the
compass housing doesn't turn.
If you're in a dense forest, you might need to
aim several times. Hopefully, you will reach your target B when you do this.
At this time, you may want to go out and do
some training, so you could check out some suggested
exercises.
Unfortunately, sometimes, for some quite often, it is even more
complicated. There is something called magnetic declination. And then,
for hiking, you wouldn't use orienteering maps. And this is the issue for lesson 3.