Problem 2.12
2.12 The observations listed below were recorded when testing the adjustment of an automatic level. Use them to calculate the collimation error in the level.
| Level position | Staff position | Sighting distance | Staff reading |
| I1 | A | 25m | 1.225m |
| I1 | B | 25m | 1.090m |
| I2 | A | 55m | 1.314m |
| I2 | B | 5m | 1.155m |
Expert Answer ♥♥♥
Instrument at I1, Instrument at I2,
True difference in level between A and B Apparent level difference between A and B
= 1.225 – 1.090 = 1.314 – 1.155
= 0.135m A is lower = 0.159m A is lower
Therefore, connecting reading at A = Reading at B + 0.135
= 1.155 + 0.135 = 1.290m
Observed reading at A = 1.314m
1.314m > 1.290, the line of collimation is upward elevated,
Collimation error in 50m, = 1.314 – 1.290 = 0.024m
Collimation error in 55m, = 0.024 x = 0.0264m