The following readings were taken with a Dumpy level and a 4 m levelling staff on a continuously sloping ground atm intervals : 0.m, 1.m, 1.m, 2.m, 2.m, 3.m, 1.m. The R.L. of the fourth point was calculated to be 79.m. The R.L. of the point that was read 0.m is |