What are the various sources of error in chain Survey?

Errors in chaining are of three types.
a.
Instrumental errors.
b.
Natural errors.
c.
Personal errors.
Various sources of these errors.1.
Error in length of chain or tape.2.
The chain getting out of the survey line due to wrong ranging.3.
Chain or tape not being stretched straight.4.
Sag in chain or tape.5.
Variation in temperature.6.
Variable tension in the chain.

Wrong reading, wrong recording, reading from wrong end of chain etc., are personal errors.
These errors are serious errors and cannot be detected easily.
Care should be taken to avoid such errors.
These errors may be sometimes positive and sometimes negative.he following are the examples of such errors: (i) Incorrect marking of the end of a chain.
(ii) Fractional part of chain may not be correct though total length is corrected.
(iii) Graduations in tape may not be exactly same throughout.
(iv) In the method of stepping while measuring sloping ground, plumbing may be crude.
The errors, that occur always in the same direction are called cumulative errors.
In each reading the error may be small, but when large number of measurements are made they may be considerable, since the error is always on one side.
Examples of such errors are: (i) Bad ranging (ii) Bad straightening (iii) Erroneous length of chain (iv) Temperature variation (v) Variation in applied pull (vi) Non-horizontality (vii) Sag in the chain, if suspended for measuring horizontal distance on a sloping ground.

1. Positive error
2. Negative error
3. Incorrect holding of chain
4. Reading wrongly
5. Booking wrongly