Transit Definition = A surveying instrument used to measure horizontal
and vertical angles.
Transit Setup
1. Setup
tripod so head (TOP PLATE) is about level. This will make leveling
the instrument easier. Drive tripod legs into the ground by
stepping on each leg.
2. Release
horizontal clamp screw and turn instrument until the telescope
bubble is directly over a pair of leveling screws.
3. Turn both
screws either toward or away from each other. One screw will
then be loosened by the same amount that the
other is tightened until bubble
is level.
THE LEFT
THUMB RULE STATES THAT MOVING YOUR LEFT THUMB TO THE LEFT…AS YOU
MOVE YOUR RIGHT THUMB TO THE RIGHT…WILL CAUSE THE BUBBLE TO MOVE LEFT.
MOVING YOUR LEFT THUMB TO THE RIGHT…WHILE YOUR RIGHT THUMB MOVES TO THE
LEFT…WILL CAUSE THE BUBBLE TO MOVE TOWARD THE RIGHT
4.
Turn the telescope 90 degrees until over the other set of leveling
screws or when you have only three leveling screws then over the
third screw and
adjust.
5. Repeat
the leveling procedure above alternating from one pair of leveling
screws to the other until transit is level.
Transits
Checking
Transit Accuracy
1. Set up
transit in an area that is as level as possible and which
is about 220 feet long. Place two matching level
rods or two pieces
of strapping
in the
ground about 200 feet apart with the faces toward each other.
Position and level the instrument so that the distance from
the instrument
to each rod
is the same
measure.
2. Take a
reading on each rod with the instrument (or mark each piece of
strapping where the crosshair is sighted).
3. Move transit
to another spot on the line and take readings and mark both rods
again.
4. The difference
between the marks on the rod will be the error of the instrument.
The error needs to be corrected
by a competent
repair
technician.
There
are 360 degrees in a circle. Each degree is divided into 60 minutes.
Each minute is divided into 60 seconds. So, 1 second
it 1/3600 of a degree!
If someone
says the error is 10 seconds that means the error of the transmitter
could be +/- 1/16" at 100 feet from the
transmitter.
At 200 feet,
the error would be 2 times as much.
If the error
were 15 seconds, it would be 1.5 times as much at 100 feet.
By starting
with 10 seconds and 100 feet, you can easily compute the error.
Financing
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