Bubble still follows LEFT THUMB

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Bubble still follows LEFT THUMB
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REPEAT positions a) and b) until the bubble stays
in the centre
7) Look through the optical plummet again. Loosen
the centring screw holding the theodolite to the
tripod and slide the theodolite over the tripod
HEAD until the reticle is over the station.
REPEAT 6) and 7) until the plate level bubble is
central AND the optical plummet is over the
survey station.
8) Check the plate level bubble in positions c)
and d) - 900 from position a) and b) and if
necessary remove half the bubble drift to FREEZE
the bubble.
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Bubble drift is 3 divisions
Remove half the drift i.e. 1.5 divisions
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(using two footscrews)
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The bubble is now FROZEN in 1.5 divisions to
the left
and should stay this much out wherever it is
rotated to.
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Check centring and repeat 7) and levelling
until The theodolite has been FINELY LEVELLED AND
CENTRED OVER THE SURVEY STATION.
It is now ready for referencing to a BACK SIGHT
for either measuring or setting out angles.