DETERMINATION OF GRADIENT OF THE LINE BY TANGENTIAL METHOD - Computer Programming

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## Friday, April 1, 2011

DETERMINATION OF GRADIENT OF THE LINE
BY TANGENTIAL METHOD

Aim :

To determine the gradient of the line joining the given staff stations A and B.

Instruments Required :

Theodolite, Ranging rods, Levelling staff

Given :

Elevation of B.M. = 100.000
Target distance = 1m.

Procedure :

1.      Set up the instrument approximately between the given objects and do the initial adjustments.
2.      Direct the telescope towards object A and find the vertical angles by bisecting the ranging rod at two points having a distance of lm(given).
3.      Note down the vertical angles for the ranging rod at B.
4.      Take the horizontal angles also at A and B.
 B.M.

 B

 s2

 h2

 V2

When both the observed angles are angles of elevation
B.M. = 100.000m
S = 1 m = Target distance
a1 & a2 = Vertical angle to upper and lower targets respectively.
h1 = Height of lower target above foot of ranging rod
h0 = Height of instrument above datum line

D = Horizontal distance between P and A =
V = D tan a2
R.L of H.I  = R.L. of B.M. + h0
R.L. of A = R.L. of H.I + V1- h1

D2 = D12 + D22 – 2D1D2 cosq
V0 = Level difference between A & B

Result :

The gradient of the line joining A and B =

TANGENTIAL TACHEOMETRY

 Face :  Right                                        Swing :  Right Inst at Sight to Position of vane Vertical angle Horizontal angle C D Mean A B Mean o , ,, , ,, o , ,, o , ,, , ,, o , ,, P A Top vane Bottom vane B Top vane Bottom vane Face : Left                                           Swing :   Left P A Top vane Bottom vane B Top vane Bottom vane