3. Work procedure
The substance system is a particular form of the
tangential system where the measured base is
held horizontally
The substance bar is a specially made
instrument supported on a tripod with two
sighting targets set a precise distance apart,
usually 2m.
The central target in the substance bar is placed
midway between the end targets for traverse
angle measurement and for use in sighting with
the auxiliary base method.
4. s
α
cot
2
2
α
H = cot
2
H=
Formula For Substence System
.
horizontal distance
s
α
H = cot
2
2
Usually the bar is 2m long to simplify the
calculation
H =cot
α
2
5. V = H tan θ
dH = hi ±V – hb
where dH = difference of height
hi = Height of the theodolite
V = vertical component
Hb = Height of substance bar
So, the reduced level of the staff position Y, RL y = RL X +
