Figure 5-34.--Measuring an azimuth on a map.
divide a circle into units of angular measure; and
4. Read the value of the angle from the scale; this
regardless of their shape, they consist of a scale around
is the grid azimuth of the point.
the outer edge and an index mark The INDEX MARK
is the center of the protractor circle from which all the
To plot a direction line from a known point on a map,
direction lines radiate.
refer to figure 5-35 as you study the following:
To determine the grid azimuth of a line from one
1. Convert, if necessary, the direction to
point to another on the map (from A to B or C to D), refer
to figure 5-34 as you study the following:
1. Draw a line connecting the two points.
2. Construct a north-south grid line through the
known point. Then proceed in the following steps:
2. Place the index of the protractor at the point
where the line crosses a vertical (north-south) grid line.
First, approximately align the 0°- 180° line of
3. Keeping the index at this point, align the
the protractor in a north-south direction through the
0°-180° line of the protractor on the vertical grid line.