Reciprocal levelling was conducted across a wide river to determine the difference in level of points A and B, A situated on one bank of the river and B situated on the other. The following results on the staff held vertically at A and B from level stations 1 and 2, respectively, were obtained. The level station 1 was near to A and station 2 was near to B.                    Level at                                Reading on                                                             A                     B               1                                              1.485               1.725 2                                              1.190               1.415    (a) If the reduced level of B is 55.18 m above the datum, what is the reduced level of A? (b) Assuming that the atmospheric conditions remain unchanged

Reciprocal levelling was conducted across a wide river to determine the difference in level of points A and B, A situated on one bank of the river and B situated on the other. The following results on the staff held vertically at A and B from level stations 1 and 2, respectively, were obtained. The level station 1 was near to A and station 2 was near to B.

               Level at                                Reading on

                                                            A                     B

            1                                              1.485               1.725

2                                              1.190               1.415

 (a) If the reduced level of B is 55.18 m above the datum, what is the reduced level of A?

(b) Assuming that the atmospheric conditions remain unchanged during the two sets of the

observations, calculate (i) the combined curvature and refraction correction if the distance AB is 315 m