1) Let PQR be the given line of section.
2) Mark point at 10 m intervals on this line. 3) Level is set up on a firm ground at a suitable point I1. 4) Temporary adjustment of level is done and B.S. is taken on B.M. 5) The RL of collimation (HI) is worked out by adding B.S. to the R.L. of B.M. The chain is stretched from P toward the point Q. 6) Also, the staff readings are taken at 10 m points, and entered in the I.S column against the respective changes. 7) Beside these points, the staff readings are taken at the representative points, for example slope of ground surface changes appreciably. 8) When it is found necessary to shift the instruments on account of the length of sight exceeding about 100 m or the further points not being possible to be observed owing to the irregularities of the ground, CP1 is taken at suitable position, and F.S is taken on it and entered in F.S column. 9) The instrument is then shifted and set up on firm ground at I2 as before. 10) B.S is taken on CP1 and new HI is calculated