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Azhar Shahzad

Booking and Reduction of Levels using Rise and Fall or Height of collimation (H.O.C) Method

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Using Rise / Fall Method

In this method booking is done in the following manner,

B.S I.S F.S Rise Fall R.L Remarks
2.570 - - - - 100.00 A
3.750 - 1.200 1.370 - 101.37 C.P
- - 3.750 - 0.70 100.67 B
5.620 - 4.950 1.370 0.70 - -
  • 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

B.S I.S F.S H.O.C R.L Remarks
2.50 - - 102.50 100.00 -
1.75 1 1.95 102.30 100.55 -
- 2.55 - - 99.75 -
- 2.70 - - 99.60 -
2.95 - 3.10 - 99.20 -
- - 2.75 - 99.40 -
7.20 - 7.80 - - -

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

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Guest REJMAC

Hi I need a help about this sub

I have a table of H.O.C method and I have to change it to the Rise and Fall method would you please help me 

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On 08/01/2016 at 11:16 AM, Guest REJMAC said:

Hi I need a help about this sub

I have a table of H.O.C method and I have to change it to the Rise and Fall method would you please help me 

Juss do away with d HOC column  n introduce columns of rise n fall then do dhe calculations or rather do dhe subtraction

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