THEODOLITE SURVEYING LESSON 4
TEMPORARY ADJUSTMENTS
1. Setting
up the theodolite over station
2. Levelling
of the theodolite
3. Elimination
of parallax
1.
SETTING UP THE THEODOLITE OVER STATION
a.
Spread the legs of tripod over the station
b.
Lift the theodolite from the box
c.
Fix the theodolite on the tripod head
d.
Bring the foot screws to the centre of its
run
e.
Suspend the plumb bob to the hook provided
to the theodolite
f.
Move the required leg of the tripod radially
and circumferentially till the plumbob
rests on the station
2.
LEVELLING
OF THE THEODOLITE
STEP 1
Test the adjustment of the plate level by
placing the plate level bubble parallel to any two of the three levelling screws. (as shown in the next slide)
STEP 2
a.
With these two leveling screws,
center the bubble in its vial.
b. Rotate
the instrument by 90º, and align the
plate level with the third leveling
screw. ( as shown in the next slide)
STEP 3
a.
Center the bubble in this
position by using the third leveling
screw.
b. Rotate the instrument back to the first position,
and see if the bubble remains centered.
c.Repeat
leveling in these two positions until the bubble remains centered in both
positions.
3.
ELIMINATION
OF PARALLAX
•
Focussing the Eye piece
Focus the eye piece by moving it
clockwise or
anticlockwise until cross hairs appears distinctly
towards a white paper
•
Focussing the Objective
Focus any object until it appears clearly with the help
of
focusing screw.
Now theodolite is ready for taking
readings
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