Describe in brief errors in compass survey.

Describe in brief errors in compass survey.
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1 Answer

Answer :

Errors in Compass Surveying.

The errors are classified as:

1. Instrumental errors.

2. Personal or Observational errors.

3. Errors due to External Influences (Natural errors etc.). 

(1) Instrumental errors: These errors are due to faulty compass, not being in adjustment and perfect working order i.e.

(i) The needle not being perfectly magnetized, not pointing exact meridian.

(ii) The pivot being bent and not in the center.

(iii) The pivot being dull and not sharp.

(iv) The needle not being perfectly straight.

(v) The needle and graduated ring not being horizontal.

(vi) The object vane not being in plumb.

(vii) The horse hair being loose, not straight.

(2) Personal or Observational errors:

The personal errors may be due to

(i) Inaccurate centering of compass over the station.

(ii) Inaccurate leveling of compass.

(iii) Inaccurate bisection of ranging rod or other objects.

(iv)Carelessness in taking readings.

(v) Carelessness in booking the readings in field boo

(3) Errors due to External Influences:

(i) Magnetic changes in the atmosphere -

(ii) Variations in magnetic declination.

(iii) Local attraction due to proximity of electric lines, steel structures etc.
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