1. LESSON 2
The stadia system
Incline Sights With
the Staff Vertical
Cont;
HOW TO ASSIGN FOR ZENITH ANGLE

2. •Positive (+) for angles of the elevation,
•Negative (-) for angles depression
LEFT FACE
00 / 3600
00 / 3600
2700
900
1800
RIGHT FACE
2700
900
1800
• Not used in tachymetry –in tachymetry must have value of θ

3. •Positive (+) for angles of the elevation
LEFT FACE
2700
00 / 3600
00 / 3600
θ < 90
0
δ
RIGHT FACE
δ
900
900
270
θ > 2700
0
1800
Formula for left face θ = 900- δ
Vertical angle = 880
Zenith angle, θ = 900- 880 = + 20
1800
Formula for right face θ = δ - 2700
Vertical angle = 2720
Zenith angle, θ = 2720- 2700 = + 20

4. •Negative (-) for angles depression
LEFT FACE
2700
00 / 3600
00 / 3600
θ > 900
900
δ
1800
Formula for left face θ = 900- δ
vertical angle = 930
Zenith angle, θ = 900- 930 = - 30
2700
RIGHT FACE
900
θ < 2700
δ
1800
Formula for right face θ = δ - 2700
vertical angle = 2670
Zenith angle, θ = 2670- 2700 = - 30

5. Zenith angle
Prepared by: masksedah

6. Zenith angle
Prepared by: masksedah