Copyright Goodheart-Willcox Co., Inc.
Chapter 8 Building Layout 161
P R O C E D U R E
Sighting
Most builder’s levels have a telescope with a power of
about 20×. This means that the object being sighted
appears to be 20 times closer than it actually is. The
procedure for sighting is easy to learn:
1. Line up the telescope by sighting along the barrel
and then look into the eyepiece, Figure 8‑16.
2. Adjust the focusing knob until the image is clear and
sharp.
3. When the crosshairs are in approximate position on
the object, Figure 8‑17, tighten the horizontal-motion
clamp.
4. Make the final alignment by turning the tangent screw.
8.5 Using Leveling
Instruments
A carpenter can use a leveling instrument to prepare
the building site for excavation and grade leveling.
The following are jobs that can be done with leveling
instruments:■
■ Locating the building lines and laying out
horizontal angles (square corners) ■
■■ Finding grade levels and elevations
■ Determining plumb (vertical) lines
8.5.1 The Horizontal Graduated Circle
Laying out corners with the transit requires an under-
standing of how the horizontal graduated circle is
marked. It is divided into spaces of 1°, Figure 8‑18.
Bubble
Goodheart-Willcox Publisher
Figure 8‑15. The bubble of the level vial will generally move
in the same direction as the left thumb. This bubble needs
to move left.
Photo courtesy of Robert Bosch Tool Corporation®
Figure 8‑16. Sighting a level line with an auto level. Both
eyes are kept open during sighting. This reduces eyestrain
and provides the best view. Hand signals are used when the
rod holder is out of earshot.
Crosshairs
A
Goodheart-Willcox Publisher
Figure 8‑17. View through the telescope. A—Crosshairs
vertically and horizontally split the image area in half.
B—The object in the view should be centered on the
crosshairs.
B
360°
45°
1°
90°
90° =square corner
=1 quadrant
Measurements of a circle
Circle
1°
1 minute
1 quadrant
=360°
=60 minutes
=60 seconds
=1/4 circle or 90°
180°
270°
Goodheart-Willcox Publisher
Figure 8‑18. The graduated circle of a transit corresponds to
the 360° of a full circle 90° represents a quadrant, which
would give you a square corner for a building.
3
Chapter 8 Building Layout 161
P R O C E D U R E
Sighting
Most builder’s levels have a telescope with a power of
about 20×. This means that the object being sighted
appears to be 20 times closer than it actually is. The
procedure for sighting is easy to learn:
1. Line up the telescope by sighting along the barrel
and then look into the eyepiece, Figure 8‑16.
2. Adjust the focusing knob until the image is clear and
sharp.
3. When the crosshairs are in approximate position on
the object, Figure 8‑17, tighten the horizontal-motion
clamp.
4. Make the final alignment by turning the tangent screw.
8.5 Using Leveling
Instruments
A carpenter can use a leveling instrument to prepare
the building site for excavation and grade leveling.
The following are jobs that can be done with leveling
instruments:■
■ Locating the building lines and laying out
horizontal angles (square corners) ■
■■ Finding grade levels and elevations
■ Determining plumb (vertical) lines
8.5.1 The Horizontal Graduated Circle
Laying out corners with the transit requires an under-
standing of how the horizontal graduated circle is
marked. It is divided into spaces of 1°, Figure 8‑18.
Bubble
Goodheart-Willcox Publisher
Figure 8‑15. The bubble of the level vial will generally move
in the same direction as the left thumb. This bubble needs
to move left.
Photo courtesy of Robert Bosch Tool Corporation®
Figure 8‑16. Sighting a level line with an auto level. Both
eyes are kept open during sighting. This reduces eyestrain
and provides the best view. Hand signals are used when the
rod holder is out of earshot.
Crosshairs
A
Goodheart-Willcox Publisher
Figure 8‑17. View through the telescope. A—Crosshairs
vertically and horizontally split the image area in half.
B—The object in the view should be centered on the
crosshairs.
B
360°
45°
1°
90°
90° =square corner
=1 quadrant
Measurements of a circle
Circle
1°
1 minute
1 quadrant
=360°
=60 minutes
=60 seconds
=1/4 circle or 90°
180°
270°
Goodheart-Willcox Publisher
Figure 8‑18. The graduated circle of a transit corresponds to
the 360° of a full circle 90° represents a quadrant, which
would give you a square corner for a building.
3