fos common errors in leveling

Imperfect adjustment of instrument

This could be eliminated by adjusting the instrument or by balancing the sum of foresight and backsight.

Rod not of standard length.

This could be eliminated by standardizing the rod and apply corrections same as for tape.

Parallax

This could be eliminated by focusing carefully.

Bubble not centered at instant of sighting

This could be eliminated by checking the bubble before making each sight.

Rod not held plumb.

This could be eliminated by waving the rod or using the rod level

Faulty of reading the rod.

This could be eliminated by checking each rod reading before recording.

Faulty turning point

This could be eliminated by choosing definite and stable points.

Variation of temperature.

This could be eliminated by protecting the level from the sun while making observations.

Earth’s curvature

This could be eliminated by balancing each backsight distance, or apply the computed correction.

Atmospheric refraction.

This could be eliminated by balancing each backsight and foresight distance also take short sights well above ground and take backsight and foresight readings quick succession.