for engineering student of semester 1

1. Prepared by:-
Nikul pithva(m-36)
Rabari tagesh(m-35)
Instrument of levelling
ECE(210004)
Guided by:-
Nutan Patel
Mechanical department

2. The art of determining the relative heights
(elevations) of different points on or below the
surface of the earth is known as levelling.
Aims of levelling:-
The aim of levelling is to determine the relative
heights of different points on or below the surface
of the undulation of the earth and to determine
the undulation of the ground.
INTRODUCATION

3. The instruments commanly used in
levelling are:-
1) A level
2) A levelling staff

4. 1) Dumpy level:-

5. description of dumpy level:-
1) Tripod stand :-
 The tripod stand consists of three legs which
may be solid or telescopic.
 The legs are made of wood or aluminium.
 The lower ends of the legs are fitted with
iron shoes.
2) Levelling Head:-
 The levelling head consists of two parallel
plates (trivet and tribrach) having three
grooves to support the foot screws.

6. 3) Foot screws:-
 Three foot screws are provided between the
trivet and tribrach.
 These are used for levelling.
 By turning the foot screws the tribrach can
be raised or lowered to bring the bubble to
the centre of its run.

7. 4) Telescope:-
 The telescope consists of two metal tubes.
 One moving within inside of other.
 It also consists of an object glass and eye-
piece on opposite ends.
 A diaphragm is fixed with the telescope just
in front of the eyes.

8. 5) Bubble tubes:-
 the bubble tubes are fixed on top of the
telescope.
 Two bubble tubes, one called the
longitudinal bubble tube and other the
cross-bubble tube, are placed at right
angles to each others.
 These tubes contain spirit bubble.
6) compass:-
 In some instrument compass is provided
just below the telescope for measuring

9. 7) Axis of the telescope:-
 This axis is an imaginary line passing
through the optical centre of the object
glass and the optical centre of the eye
piece.
8) Line of collimation:-
 It is an imaginary line passing through
the intersection of the cross-hairs at the
diaphragm and the optical centre of the
object glass and its continuation.
 It is also known as the line of sight.

10. 2) Levelliing staff:-
The levelling staff is used for measuring the
vertical distances between the points on the
ground and the line of collimation.
Types of levelling staves:
1. Self reading:
a) Solid staff
b) Telescopic staff
c) Folding staff

11. a) Solid staff:-
the metric solid staff
is generally 3 m long,
75 mm wide and 25
mm thick, with a metal
shoe at the bottom,
and graduated on one
face.
The smallest division
is of 5 mm in metric
system.
They are generally
made of good-quality
Fig. Solid staff

12. b) Telescopic staff:-
A telescopic staff consists of
two hollow pieces and one
solid top piece, each
telescoping into the bottom
one.
When the staff is folded up,
it is only a little longer than
the lowest piece.
When the upper sections are
pulled out for use, they are
engaged and held by brass
spring-catches.
It is thus longer than a solid
staff up to 4 m to 6 m.
Fig. telescopic staff

13. c) Folding staff:-
A folding staff is
generally 4 m long
and is divided into
two equal parts of 2
m each.
It is hinged in the
middle so that top
half can be folded
over to lie against
the lower half.
Fig. Folding staff

14. 2) Target staff:-
A target staff has a sliding target equipped
with vernier which can be clamped at any point
along the staff.
For taking the reading ,the level man directs
the staff man to raise or lower the target till it is
bisected by the line of sight.

15. Thank you