Repetition Method|Civil Easy Learning

 Repetition Method

 This method is used for very accurate work. In this method ,the same angle is added several times mechanically and the correct value of the angle is obtained by dividing the accumulated reading by the no. of repetitions.

The No. of repetitions made usually in this method is six, three with the face left and three with the face right .In this way ,angles can be measured to a finer degree of accuracy than that obtainable with the least count of the vernier.

 Repetition Method.To measure horizontal angle by repetitions:-

  

repetition-method

i) Set up the theodolite at starting point O and level it accurately.

ii) Measure The horizontal angle AOB.

iii) Loosen the lower clamp and turn the telescope clock – wise until the object (A) is sighted again. Bisect B accurately by using the upper tangent screw. The verniers will now read the twice the value of the angle now.

iv) Repeat the process until the angle is repeated the required number of times (usually 3). Read again both verniers . The final reading after n repetitions should be approximately n X (angle). Divide the sum by the number of repetitions and the result thus obtained gives the correct value of the angle AOB.

v) Change the face of the instrument. Repeat exactly in the same manner and find another value of the angle AOB. The average of two readings gives the required precise value of the angle AOB.