(a) The term "Error of closure" is the failure of the end point of a closed traverse to fall exactly on the point of origin of the traverse. The error can only be known when the field details are plotted.
(b) Sources of error of closure:
(i) Inaccurate measurement of the sides.
(ii) Wrong bookings of bearing.
(iii) Taking wrong bearing
(iv) Inaccurate booking of all measurements
(v) Using faulty instrument.
(vi) Mistakes in actual plotting.
(vii) Possible effects on magnetic compass by magnetic material.
(c) Measures to avoid an error of closure:
(a) Cross-check the functionality of all instrument.
(b) Check the measurement on the plan plotted.
(c) Take backward bearing as well as on bearing to check errors in measurement of bearing.
(d) Check presence of magnetic materials on and around the user.