12. STADIA DISTANCE MEASURING
Distance measurement can be done using the stadia hairs of the reticle.
Read the length " " of a level rod shown between the stadia hairs. The distance to
the target is 100 multiplied by . The distance between point A and point B is L.
L = 100 x
On a rod showing inches & eighths, you must convert the inches & eighths to the
decimal form of a foot to get a correct reading. This is done by taking the partial
foot reading, say 7 1/8 inches, and converting by dividing by 12.
= 7.125"/12 = .59 FT.
L = .59 x 100 = 59 FT.
If were 1' 7 1/8" then would equal 1.59 ft. & L = 159 ft.
Berger Instruments • 15
11. PRACTICAL APPLICATIONS
11.1. Grade Line for a Sewer
Steps to find the slope necessary for a household sewer connection are shown below
(
Fig. 17
). Notice that the invert or flow-line of the pipe is used in each instance. The
invert is the bottom of the pipe and this line is the reference from which grades are
commonly given.
11.2. Batter Boards for a Sewer
Sewers are normally placed at some depth below the surface of the ground, so
batter boards are placed somewhat higher above the invert grade. A typical layout
for sewer batter boards is shown below (
Fig.18
). The vertical strip nailed to the
horizontal board is set with one edge along the line of the sewer. A nail is placed in
this vertical strip at an even number of feet above the invert. By stretching a taut line
between these nails, the sewer line is easily referenced. A board notched say 8 feet
from its bottom is used to set the pipe.
14 • Berger Instruments
Cesspool inlet 69"-22"=47" below dwe
Horizontal distance=78'.4 47"=3'.92
Grade of sewer=100x(3.92/78.4)=5%
Grade 5%
69"
22"
Fig. 17
CUT 2'
FILL 3'
Detail of grade
stake of A
Detail of grade
stake of B
Driveway
grade marked on stakes
Driveway center line
A
B
12'
90
°
90
°
15'
15'
15'
15'
Offset Grade Stakes for
a 12 foot Driveway
Fig. 18
Fig. 19
Upper Stadia Hair
Lower Stadia Hair
