TM 5-6675-328-14
Azimuth ...................................................................................... Direction in horizontal
plane.
Buck In ....................................................................................... To place an instrument so
that the line-of-sight is
alined at both a far
and near target. It is
usually accomplished by
trial and error.
Collimation ................................................................................. To place an instrument
so that the line-of-
sight is alined at both
a far and near target.
Bull's-Eye Level .......................................................................... Concentric level
attached to an instru-
ment.
Elevation Axis ............................................................................ The rotation of a
telescope in a vertical
plane.
Eyepiece Lens ............................................................................ Lens closest to the eye.
Focus ......................................................................................... To move optical parts so
that a sharp image is
seen.
Horizontal . ................................................................................. Parallel to or in the
plane of the horizon.
Objective Lens............................................................................ Lens closest to the
object being viewed.
Plunge . ...................................................................................... To rotate an optical
sighting telescope 1800
in vertical plane.
Reference Line . ......................................................................... The line of sight from
which measurements are
made.
Tangent Screw ........................................................................... A hand-operated screw
which changes the direc-
tion of the line-of-sight
in either azimuth or
elevation.
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