To Plum a Vertical Column
10. SLOPES AND RATES OF GRADES
Definitions of Grade and Slopes
Several methods of defining slopes are shown above (
Fig. 16
).
1. Horizontal distance to rise (or fall) in vertical; thus the grade is 4 to 1, or, more
completely, 4
horizontal
to 1
vertical
.
2. Rise or fall for each 100 feet horizontal. The slope, if extended for 100 feet
horizontally would rise 25 feet. This is referred to as a 25% slope.
3. Rise or fall for each one foot horizontal. Again, this would be designated as 0.25
foot per foot, or three inches per foot.
4. Angle of slope is 14 degrees, 2 minutes (14° 2').
Berger Instruments • 13
9. SPECIAL USES OF TRANSIT-LEVEL INSTRUMENTS
In the following three sections, two special operations are illustrated which can be
performed with instruments of the
transit-level type
but cannot be performed
with a dumpy level. When leveling lock is engaged, it converts the transit-level to a
level, so all other functions described in this manual can be performed.
9.1 Setting Points in Line
Points A and B are two points which are on a line such as a property boundary
(
Fig. 14
). When erecting a fence, additional points between A and B and also on the
other side of B from A may be needed. Center and level your instrument over point
A; sight on point B. Bring vertical hair exactly on point B by means of the horizontal
clamp and tangent screw. A pencil held vertically at B is useful to show this point.
Keeping horizontal clamp tightened, depress the telescope to set points between A
and B on line.
If the top of a stake cannot be seen, when you come to set point C, sight with the
aid of a plumb bob: first, to find where to drive the stake, and secondly, to note the
point on the top of the stake.
If it is necessary to continue this line beyond point C, center and level your
instrument over point B, sight point C and continue this procedure.
9.2 Plumbing
Instruments of the transit-level type can be used to advantage in plumbing such
objects as building walls, columns and flagpoles. Set and level your instrument at a
point which is about as far away from the object as the object is tall. Select a point at
the base of the object which is to be plumbed; sight your telescope on this point
and set the intersection of cross wires directly on it. By raising your telescope, you
will find, through use of the line of sight and the crosshairs, whether or not the
object is plumb. If it is plumb, the object will appear not to move away from the
crosshair intersection. To completely check the plumb of the object, set the
instrument at a position which is at an angle of 90° from the first position of the
instrument and repeat the procedure. A corner post of a wood frame building is
shown (
Fig. 15
) being plumbed.
12 • Berger Instruments
A
B
C
Fig. 14
To Continue line beyond C, set Transit-Level over B,
sight C, and continue process
B
90
°
A
Fig. 15
PROCEDURE:
At A, sight outside edge of corner post at the base.
Raise line of sight to top of post. Bring outside
edge to line of sight. Nail brace facing instrument.
Repeat process with instrument at B.
4
1
14
°
02'
+25%
25 ft.
100 ft.
Fig. 16