272 SURVEYING Example 6.2. The following consecutive readings were taken with a level and a 4 m staff on a continuously sloping ground at a common interval of 20 metres : 0.855 (on Q), 1.545, 2.335, 3.115, 3.825, 0.455, 1.380, 2.055, 2.855, 3.455, 0.585, 1.015, 1.850, 1.850, 2.755, and 3.845 (on R). Enter the readings as on a field book page, reduce the levels, apply the checks and determine the gradient of line QR.​