To determine the horizontal distance between the two terminal stations on sloping ground by using Abney Level.

Object: To determine the horizontal distance between the two terminal stations on a sloping ground by using Abney Level.

USING ABNEY LEVEL

Instruments required:

1. Ranging rods
2. Abney level
3. Tape
4. Field book

Theory:

When the slopes of hill are at greater height and inclined at a certain higher angle, in this case stepping method may not be applicable. In such a case, various slopes are measured by using Abney level. By knowing the angle of slope of hill and inclined distance, horizontal distance can be calculated as follows:

Let ‘L’ is the inclined distance, ‘𝜃’ is the angle of slope and ‘D’ is the horizontal

distance.

Then the required horizontal distance is:

D = L cos (𝜃)

Procedure:

• Let the end stations are A and B and the intermediate stations are P and Q.
• The follower holds the zero end of tape at end station A on the ground, while the leader stretches it inclined at the end station B, such that the tape passes along the foots of the intermediate stations and measures the inclined distance L.
• Then a mark is made on a ranging rod on the end station B at the height of the observer’s eye at the end station A and measures the angle of slope ‘𝜃’ and notes all data in the field book.
• While measuring the angle, the observer should take care of the target i.e. the mark so that it must be easily visible to him through Abney level and the bubble must coincide with the horizontal line as viewed from the eyepiece of Abney level.

Results:

Calculations:

D=L Cos 𝜃