## Height of Instrument Method | Surveying and Levelling

#### 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