TM 9-1290-357-15
(4) Turn azimuth knob (fig. 1-2) until the
g. Check that bubble in circular level vial is
verticle centerline of the reticle is on the unknown
centered in any position of azimuth rotation.
point to which the measurement is to be made.
h. When using a tripod, spread legs and em-
The azimuth worm shoe (throw-out device) lever
bed the feet in firm ground. Adjust the extensible
may be pushed forward for making azimuth
legs for length in order to bring the tripod head
changes rapidly. Observe the azimuth scale, us-
into an approximately level plane. When adjusting
ing the main graduations (upper) for values from
the legs keep the clamping screws lightly loose
3,200 mils and up. Angular indications correspond-
until tripod has finally been positioned, then
ing to those on panoramic telescopes with 03,200
tighten them securely.
mil scales may be read using the auxiliary (lower)
graduations for azimuths from 3,200 mils up.
Caution: Make certain that clamps are tight,
otherwise it may damage equipment.
Caution: Care must be exercised that clamp-
ing screw is tightly secured before turning the
telescope by means of the azimuth knob or the
2-8. Preparation for Use
azimuth worm shoe (throughout device), and
a. Remove the carrying case housing the aim-
that the position of tripod is not disturbed dur-
ing circle M1 w/e from its stowed position.
ing the operation of the azimuth knob.
b. Remove the aiming circle M1 from case and
b. Orientation. By orienting the aiming circle
remove cover (fig. 11).
M1, the azimuth scale can be made to read direct-
c. Fasten the instrument securely on the tri-
ly in terms of azimuth from north or any other
pod spindle.
reference direction. The orientation mechanism
must not be disturbed after completion of orien-
Note. Make certain the tripod feet have been firmly
tation. Any one of the following methods listed
embedded in ground before fastening the instrument.
in (1) and (2) may be used for orienting:
d. Level the instrument with the tripod ball
(1) Orientation on a datum point of known
and socket joint observing the circular level (fig.
to the known azimuth of the datum point. Posi-
Caution: The aiming circle compass cannot
tion aiming circle M1 until the datum point ap-
be used near steel or iron masses. Such masses
pears on the crosslines of the reticle, by loosening
will cause inaccurate readings when measuring
clamping screw, rotating the instrument for coarse
angles if the compass needle is used as the basis.
adjustment, tightening clamping screw, and then
turning the orienting knob for fine adjustment.
e. Install batteries in battery case of instru-
The telescope may be elevated or depressed as re-
ment light M2 and install light on tripod (fig.
quired to bring the datum point into the field of
view.
Warning: When not using instrument remove
(2) Orientation on grid north (Y-worth).
battery from instrument light M2.
Determine the declination constant by setting up
the aiming circle over a declination station (any
point from which other well defined points of
known Yazimuth can be seen) and carefully level
a. Measuring Horizontal Angles.
instrument. Set scales at zero and center the mag-
netic needle. Turn azimuth knob to a point of
(1) Level the instrument as outlined in para-
known azimuth and record this indication. Repeat
graph 2-7 c and d above.
this process three times subtracting the mean of
(2) With the azimuth knob (fig. 1-2), set
this indications from the known Y-azimuth (add
the azimuth scale and micrometer at zero.
6,400 mils to the Yazimuth, if necessary). The
(3) Using the orienting mechanism clamp-
result is the declination constant of the instru-
ing screw and orienting knob, (fig. 12) adjust
ment. If more than one point of known Y-azimuth
the instrument until the vertical centerline of the
can be seen, repeat the computations for each
telescope reticle (fig. 1-4) is on the known point
point and take the mean of the differences as the
from which the measurement is made. Check level
declination constant on the azimuth scale. Center
of instrument.
the needle on the needle index using the orienting
