4. As the deflection setting on the sight
plotted, count up 500 meters and make a pencil
is right 30, the deflection to be given to the
dot. This is the location of the second section.
weapon is right 35 (right 30 plus right 6 to the
Note. To determine the azimuth and distance
nearest 5-mil graduation).
from the first section to the second section, rotate the
disk until the plotted location of the second section is _
d. Solving of Survey Notes.
toward the top of the plotting board and is on the same
(1) Given. The weapon personnel are placed
vertical line, or the same distance from the same
vertical line, as the first section plot (in this case on the
in position by section, each section in a different
red index line). The azimuth is 4134 mils and the distance
location. The first section is plotted at the pivot
is 861 meters.
point of the plotting board. The second section is
located (surveyed) with reference to the first sec-
tion by compass and pacing. A traverse of two
legs is made to the second section from the first
a. With one extremity of the dial index line in
coincidence with each of the diametrical center-
lines of the base, the other extremity of the index
( a ) First leg:
line shall not be more than 5 mils out of coinci-
Distance 400 meters
dence with the corresponding base centerline.
(b) Second leg:
Distance 500 meters
b. The plotting board accuracy for the weap-
on-target (WT) line shall be within 5.0 mils
(2) Procedure. To plot the location of the
as determined by placing pencil dots at the tar-
second section with reference to the first section,
g e t (T) and weapon (W) points as measured
proceed as indicated in (a) through (c) below.
from observer (O) (represented by the center
(a) Use the range scale along the index
pivoting point of the dial) using the OT and OW
values specified above. When a line is drawn
(b) Rotate the disk until azimuth 3800 is
through the WT dots, the WT line is then laid
at the index mark. Count up 400 meters along
the red index line and make a pencil dot.
parallel to the base O centerline (index line, fig.
13) and the WT mil value is determined from
(c) Rotate the disk until azimuth 4400 is
a t the index mark. From the pencil dot just
the mil scale (azimuth scale, fig. 1-4) on the dial.
OPERATION UNDER UNUSUAL CONDITIONS
c. Do not permit the accumulation of snow or
ice on the plotting board. When not in use, al-
In addition to the normal operating procedures
ways keep the plotting board inside carrying case
for usual conditions described in section II, spe-
M72 to prevent such accumulation and/or dam-
cial instructions for operating under unusual con-
age or destruction.
ditions are contained herein. In addition to the
d. Never apply heat from strongly concen-
normal preventative-maintenance services, special
t r a t e d sources directly to an extremely cold
care in cleaning and handling must be observed
plotting board. Sudden great temperature changes
where extremes of temperature and atmospheric
may cause breakage of the component parts of
conditions are present. Proper cleaning and hand-
the plotting board or it may result in nonadher-
ling not only insure proper operation and func-
ence of the bonded components due to "breaking-
tioning, but also guard against breakage and/
up" of the bond.
or deterioration of the materiel.
2-13. Operation under Dusty or Sandy
2-12. Operation in Extreme Cold
Under extremely dusty or sandy conditions,
a. In temperatures below freezing, it is neces-
extra care must be exercised when cleaning the
sary that extra care be used when handling the
plotting board so that scratching of the trans-
plotting board. Extreme cold will make the plas-
parent plastic s u r f a c e s d o e s n o t o c c u r .
tic material of the board more brittle, hence it
S u c h scratching will damage the transparent
will be more easily broken if dropped or struck
quality of the base grid and azimuth disk sur-
against other objects
faces. Excessive scratching will cause damage
b. Use a dry cloth for cleaning. A water dam-
and/or destruction of the lines of the vernier
pened cloth will either freeze to the plotting
and scales and render the plotting board difficult
board or it will leave a film of ice on the board
to read and/or useless. Shake all dust and sand
and make it inoperable.
from the carrying case.