## Using Rise / Fall Method

In this method booking is done in the following manner,

• On any page of book the first reading is always a B.S and last reading is always a F.S. If you are not getting F.S as last reading on each page then it means you have done mistake while booking readings.
• From the B.S next F.S is subtracted. If the answer is +ve it will be Rise and if the answer is -ve it be Fall and put that reading in respective box.
• In the above table, I have assumed that Reduce Level (R.L) of point A is 100.0 and you can see R.L of point B is 100.67, which shows that point B is .67 units higher than point A.

In case of numerous readings the check should be applied at the end of each page while booking reading,

∑ (B.S) – ∑ (F.S) = ∑ Rise – ∑ Fall = R.L of last point – R.L of first point 5.620 – 4.950 = 1.37 – 0.70 = 100.67 – 100 0.67 = 0.67 = 0.67

## Using Height of collimation Method (H.O.C)

For this method use the following formulas,

R.L + B.S = H.O.C and H.O.C – F.S = R.L

All other considerations are same as Rise/ Fall method. Below check have applied,

∑ (B.S) – ∑ (F.S) = R.L of last point – R.L of first point = 7.2 – 7.8 = 99.4 – 100 = -0.6 = -0.6