TM 5-6675-270-15
e. Refer to figure 2-25 and level the theodolite.
f. Focus the telescope as follows:
(1) Direct the telescope towards a uniformly
light background. Turn the scale dial (fig. l-l
and l-2) on the telescope eyepiece until the cross-
lines are sharp and black.
NOTE
Observe the settings on the scale dial. This
setting will remain constant for the same ob-
server but will vary for other observers.
(2) Turn the focus drive (fig. 1-1 and l-2)
until there appears a clear image of the object
sighted.
g. The horizontal and vertical circle reading
scales are both observed through the microscope
eyepiece (fig. 2-14 and 2-15). The horizontal
circle scale image appears in the upper half of
the window. The circles of the 0.2 MIL theodolite
both horizontal and vertical are graduated in mils,
and can be read directly to 0.2 mil (fig.
and estimated to the nearest 0.1 mil. The main
scales are marked and numbered every 10 mils,
with the last zero dropped. The auxiliary scales
are graduated from 0 to 10 mils in 0.2 mil incre-
ments. The circles are read by using the l0-mil
graduation which passes through the auxiliary
Figure 2-22. Compass adjustment.
scale as the index line. The reading under this
line is added to the l0-mil value for the total..
It is good practice to set the horizontal circle
2-10. Operation of Equipment
to 0.1 mil for initial reading. This eliminates work-
a. Set up the theodolite on the tripod (para
ing values less than zero when computing a mean
of direct and reverse pointings. The circles of the
l-MIN theodolite, both horizontal and vertical,
b. If necessary, install the electrica. illumina-
They are
are graduated in degrees (fig.
tion system (para 2-3).
graduated from 0 to 360 degree with a major or index
NOTE
graduation for each degree. This degree index
To operate the illumination system, position the
rheostat knob for desired brilliance and place the
mark appears superimposed over the auxiliary
hand light switch in the ON position.
scale which is graduated in minutes to cover 60'
c. Install the eyepiece prisms and sunglass, if
or 1 degree. The position of the degree mark on
required (para 2-3).
the auxiliary scale is used as an index to get a direct
d. Perform the operator's daily services (para
reading in degrees and minutes. The scale can
be estimated to the nearest 0.1' arc.
2-23
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