PROBLEMS OF CORRECTIONS

Chain Length is Longer than Actual

Example 3.1: Length of a line measured with a 20 meter chain was found to be 250 meter. Calculate the true length of the line if chain was 10 cm longer than actual.

Correction of Measuring Chain

Example 3.2: Length of a line measured with a 20 meter chain was found to be 1200 m. As a check, the length was again measured with a 25 m chain and found 1212 m. On comparing the 20 m chain with test gauge, it was found to be 1 decimeter longer. Find the actual length of 25 m chain used.

Temperature/ Stretching Correction

Example 3.3: A 20 m chain was found to be 10 cm longer after chaining 1500 m. It was found to be 18 cm longer at the end of day’s work after chaining 2900 m. Find the true distance if the chain was correct before commencement of work.

Area Correction

Example 3.6: The area of the plan of an old survey plotted to a scale of 10 m to 1 cm measured now as 100.2 sq. cm as found by a planiometer. The plan is found to have shrunk so that a line originally 10 cm long now measures 9.7 cm only. There was also a note on the plan that 20 m chain used was 8 cm shorter than actual. Find out the true area of the survey