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Section 1  Preparing to Build
the circle. That number is 45. The reading is 75°,
plus the number on the vernier, 45 minutes.
Vernier scales will not be the same on all
instruments. Study the operator’s manual for
instructions about the particular model you are
using.
6.5.2 Laying Out and
Staking a Building
Staking out is done before establishing the
grade level. It begins with locating the lot lines.
Corners of the lot should normally be marked
with stakes. Then, proceed:
1. Center and level the instrument (builder’s
level or transit) over the lot corner stake.
Measure the setback called for by local codes.
Sight across to the opposite corner stake.
2. Drive a 2 × 2 stake at the setback in line with
the lot stakes. Use the transit or builder’s level
to check alignment. The vertical and horizontal
crosshairs should center on the top of the stake.
Drive a nail in the top-center of the stake.
3. Place another stake at the correct setback for
one side of the property line. You are now
ready to stake out the building lines.
Staking a building
Staking out building lines requires two persons.
When a builder’s level is used, the second person
will use a rod that must be plumbed along the line
of sight. Since a transit can pivot up and down,
the second person uses a stake to locate corners
along the building line.
1. Attach a plumb bob to the center screw or
hook on the underside of the instrument. Some
instruments have an optical plumb for zeroing
in over a point. Shift the tripod until the point of
the plumb bob is directly over the point marking
the corner of the building lines. This is at point
A on line AB, as shown in Figure 6-15.
2. Level the instrument before proceeding further.
Recheck for plumb.
3. From point A (or station A), turn the telescope
so the vertical crosshair is directly in line with
the edge of a stake or rod held at point B. When
using a transit, sight the telescope on the stake.
4. Use a measuring tape along line AB to locate
distance to the corner. Drive a corner stake at
this point.
5. Set the horizontal circle on the instrument at
zero to align with the vernier zero and swing the
instrument 90° (or any other required angle).
6. Position the rod or stake along line AC so it
aligns with the crosshairs.
7. Locate the other corner along line AC using a
measuring tape.
8. Move the instrument to point C, sight back to
point A and then turn 90° to locate the line of
sight to point D.
9. Measure the distance to point D and place a
stake.
10. Use a measuring tape to check the diagonal
distances. If these are equal, the building line
is square.
If the resulting figure is a rectangle or square, you
have completed the layout. However, you may want to
move the instrument to point D to check your work.
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75°, 45 Minutes
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75°
Vernier scale
Figure 6-14. Reading the horizontal circle of a transit.
A—When the zero mark of the vernier is exactly on a
degree mark, the reading is an even degree. In this
case, the reading is 75°. B—When the zero mark is
between degrees, read across the vernier to find the
minute mark that aligns with a degree mark. This
reading is 75°, 45′. (David White)