Height of the Instrument Method
The following readings were observed with a levelling instrument, the instrument was shifted after 5th and 11th reading.
0.585, 1.010, 1.735, 3.295, 3.775(5th)
0.350, 1.300, 1.795, 2.575, 3.375
3.895 (11th), 1.735, 0.635, 1.605
Determine the RLs of various points if the reduced level (RL) of a point on which the first reading was taken is 136.440 gives the height of collimation method and applies the check.
| Station | BS | IS | FS | HI | RL | Remarks |
| 123
4 5 |
0.585
0.350 |
1.0101.735
3.295 |
3.775 |
137.025
133.600 |
136.440136.015135.290
133.730 133.250 |
RL of I point
CPI |
| 678
9 10 |
1.735 |
1.3001.7952.575
3.375 |
3.895 |
131.440 |
132.300
131.805 131.025 130.225 129.705 |
CP II |
| 1112 | 0.635 | 1.605 | 130.805
129.835 |
|||
| Sum of BS=2.670 | Sum of FS =9.275 |
HL = RL + BS
= 136.440 + 0.585
= 137.025
RL = HL – IS
Check
(Summation of BS)-(Summation of FS) = Last RL – First RL
2.670 – 9.275 = 129.835 – 136.440
-6.605 = -6.605