U s i n g the Range Arm
The range scale (4) on grid (2) is the same
as the range scales on range arm (5).
The range scale on the left edge of the
range arm is provided for plotting problems
from below center when the range arm (5) is
removed. The arrow at 2000 meters indi-
cates the vertex of a 3200 mil protractor
when used to measure angles from maps.
To determine azimuth (a four digit number),
read the first three digits on the azimuth disk
scale to the right of the index mark on the
range arm. The fourth digit is read from the
right side of vernier (6). Starting at zero, the
lines on the vernier (6) are counted off until
the point where the vernier line coincides
with a line on the azimuth disk (1).