Reiteration Method|Civil Easy Learning

3) Reiteration Method

 This method is another precise and comparatively less tedious method of measuring the horizontal angles. It is generally preferred when several angles are to be measured at a particular station. This method consists in measuring several angles successively and finally closing the horizon at the starting point. The final reading of the vernier A should be same as its initial reading. …If not ,the discrepancy is equally distributed among all the measured angles. 

Procedure:

Suppose it is required to measure the angles AOB,BOC and COD.Then to measure these angles by repetition method :

reiteration-method

i) Set up the instrument over station point O and level it accurately.

ii) Direct the telescope towards point A which is known as referring object. Bisect it accurately and check the reading of vernier as 0 or 360 degrees. Loosen the lower clamp and turn the telescope clockwise to sight point B exactly.Read the verniers again and The mean reading will give the value of angle AOB.

iii) Similarly bisect C & D successively, read both verniers at each bisection, find the value of the angle BOC and COD.

iv) Finally close the horizon by sighting towards the referring object (point A).

v) The vernier A should now read 360degrees. If not note down the error .This error occurs due to slip etc. 

vi) If the error is small, it is equally distributed among the several angles .If large the readings should be discarded and a new set of readings be taken.