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InAngle and Bearing
-A bearing is a direction. Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.
-In trigonometry, an angle is a measure of rotation from one ray to another ray with the same endpoint. Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.
-In geometry, angles are measured without regard for direction or orientation. Either ray can be zero and the angle is always positive and between zero and 180 degrees. Angles greater than 180 degrees are called reflex angles.

*Face left & Face right*
*Face Left*: When the Vertical Circle of a Theod is situated on the left of the observer and the observation or reading taken with this face is called Face Left Observation or Reading.
*Face Right*: When the Vertical Circle of a Theod is situated on the right of the observer and the observation or reading taken with this face is called Face Right Observation or Reading

*Direct angle*: An angle measured directly between two lines, as distinguished in transit traverse from a deflection angle.
*Deflaction angle*: An angle that measures the departure of a moving object from its directed course.
The angle of a deflection shot in gunnery, measured between the line of sight to the target and the line of sight to the aiming point.

A horizontal angle is the difference between two measured directions.Horizontal angles are measured on a plane perpendicular to the vertical axis (plumb line).
Vertical angular measurements are measured to determine slope of survey lines from the horizontal plane (level line).

Spire test:.
- used to fixed the errors caused by the horizontal and vertical axis that is not perpendicular to each other on an instrument so that the horizontal measurement is totally levelled.
-if adjustment of LOS(length of site)  is done the LOS will move in a plane when telescope is plunged, this ensures that this plane will be a vertical lines.
Collimation:
- the lines of collimation of telescope should be parallel to the axis of the bubble tube.
-after accomplished the LOS will be horizontal when the bubble is at the centre.
- line of collimation is defined as line through the rear nodal point of the objective lens of the telescope and the center of the reticle when they are in perfect alignment.

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Difference between face left and face right
a) Face Left Condition : If the vertical circle is on the left side of t,he observer, the theodolite is in the face left condition. Normally, the face left condition is used in practice. The face left condition is, therefore, also known as the normal condition. The telescope is in the normal position. It is also called the direct condition

Face Right Condition : If the vertical circle is on the right side of the observer, the theodolite is in the face right condition. The telescope is in the inverted position. It is also called the reverse condition.

Difference between direct and deflection angle
Deflection angle : A deflection angle is the angle which a survey line makes with the prolongation of the preceding line.

While,

Direct angle is
an angle measured directly between two lines, as distinguished in transit traverse from a deflection angle.

Difference between angle and bearings
C) Angle and Bearing
A bearing is a direction. Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.

In trigonometry, an angle is a measure of rotation from one ray to another ray with the same endpoint. Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.

In geometry, angles are measured without regard for direction or orientation. Either ray can be zero and the angle is always positive and between zero and 180 degrees. Angles greater than 180 degrees are called reflex angles.

Difference between horizontal and vertical axis of Theodolite

*vertical axis*- it is the axis of rotation of the telescope in the horizontal plane.
*horizontal axis*-it is the axis of rotation of the telescope in the vertical plane.

Difference between spire test and collimation in azimuth test
Espire test - it is test for the adjustment of the standards and the line of of sight should be perpendicular to the vertical axis

Collimation - it's line of sight should be horizontal axis

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Face left Vs Face right
Face left :When the Vertical Circle of a Theodolite is situated on the left of the observer and the observation or reading taken with this face is called Face Left Observation or Reading.

Face Right: When the Vertical Circle of a Theod is situated on the right of the observer and the observation or reading taken with this face is called Face Right Observation or Reading. 
Direct angle Vs Deflection Angle

Direct Angle. An angle measured directly between two lines, as distinguished in transit traverse from a deflection angle.

deflection angle. i. In surveying, a horizontal angle measured from the prolongation of the preceding line to the following line. Deflection angles to the right are positive; those to the left are negative.
Angle Vs Bearing

Angle :Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.

Bearing : Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.

Horizontal vs vertical angle
Horizontal angle
These angle are used to determine the bearings and directions in control surveys,for locating detail when mapping and for setting out all types of structure.

Vertical angle
These angles are used to determine the heights of points and to calculate slope corrections

Horizontal axis Vs Vertical axis

Horizontal axis
The axis about which the telescope (theodolite) along the vertical circle rotates in vertical plane. It is known as trunnion axis

Vertical axis:it is the axis of rotation of the telescope in the horizontal plane

Spire test vs line of colimation

Spire test  is a test carried out to irradicate/remove error  due  to  non perpendicularity  of  horizontal  axis  and  the  vertical  axis in surveying
Spire Test:
1. For the desired relation, the horizontal axis should be perpendicular to the vertical axis.
2. The object of the adjustment is to make the horizontal axis is perpendicular to vertical axis so that horizontal axis is perfectly horizontal when the instrument is levelled.
3. If the adjusment of LOS is done, the LOS will move in a plane when the telescope is plunged. This ensures that this plane will be a vertical plane.

Line of collimation is the line of sight of the telescope of a surveying instrument, defined as the line through the rear nodal point of the objective lens of the telescope and the center of the reticle when they are in perfect alignment.

Collimation in Azimuth Test:
1. There are 2 adjusment which are the horizontal collimation adjusment and vertical collimation adjusment.
2. The purpose of horizontal collimation adjusting is to make the line of sight perpendicular to the horizontal axis of the telescope.
3. The purpose of vertical collimation adjusment is to make the vertical crosslime of the reticle lie in a plane perpendicular to the horizontal axis of the telescope.

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A)
Face Left
If the vertical circle of the instrument is on the left side of the observer while taking a reading, the position is called face left
Face right
If the vertical circle of the instrument is on the right side of the observer while taking a reading, the position is called face left

B)
Direct angle is an angle measured directly between two lines
Deflection angle is the horizontal angle as measured from the prolongation of the preceding transit line to the next.

C)
Bearing is a direction. Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.

In trigonometry, an angle is a measure of rotation from one ray to another ray with the same endpoint. Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.

In geometry, angles are measured without regard for direction or orientation. Either ray can be zero and the angle is always positive and between zero and 180 degrees. Angles greater than 180 degrees are called reflex angles.

D)
Horizontal axes are used to determine the bearings and directions in control surveys,
for locating detail when mapping and for setting out all types of structure.

Vertical axes
These angles are used to determine the heights of points and to calculate slope corrections

E)
Spire test
The object of the adjustment is to make the horizontal axis is perpendicular to vertical axis so that horizontal axis is perfectly horizontal when the instrument is levelled..

Collimation of azimuth test
The purpose of the horizontal collimation adjusting is to make the line of sight perpendicular to the horizontal axis to the telescope

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Differentiate between the following pairs:
a) Face left and Face right
b) Direct and deflection angles
c) Angle and Bearing
d) Horizontal and vertical axes of a theodolite
e) Spire test and collimation in azimuth test.

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A) Face Left & Face Right
Face Left Condition
If the vertical circle is on the left side of t,he observer, the theodolite is in the face left condition. Normally, the face left condition is used in practice. The face left condition is, therefore, also known as the normal condition. The telescope is in the normal position. It is also called the direct condition

Face Right Condition
If the vertical circle is on the right side of the observer, the theodolite is in the face right condition. The telescope is in the inverted position. It is also called the reverse condition.

B)  Direct and deflection
Direct angle
It is an angle measured clockwise from the preceeding survey line to the following survey line, as distinguished in transit tranverse from a deflection angle.

Deflection angle
In surveying, a horizontal angle measured from prolongation of the preceding transit line to the next line; recorded as “right” if clockwise rotation and “left” if counterclockwise.

C) Angle and Bearing
Angle
-an angle is a measure of rotation from one ray to another ray with the same endpoint.
-Angles are measured counter clockwise from the positive x-axis which is zero degrees.
-measured without regard for direction or orientation.
-Either ray can be zero and the angle is always positive and between zero and 180 degrees.
-Angles greater than 180 degrees are called reflex angles.

Bearing
- A bearing is a direction.
- A bearing indicated relative to a reference.
- Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.
- A bearing of 45 degrees usually means angle of 45 degrees on the compass dial clockwise from true north.

D) Horizontal and vertical axes
Vertical Axis
It is the axis of rotation of the telescope in the horizontal plane.

Horizontal axis
It is the axis of rotation of the telescope in the vertical plane

E) Spire test & collimation on azimuth test
Spire test

Error due to non perpendicularity of horizontal axis and the vertical axis, and if the test is there, what is the test, how to carry it out. Well, the test is called spire, spire test, and as the name is there what we do, at a distance from us let us say a 25 meters from us.

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1) Face left and face right
Face Left Condition : If the vertical circle is on the left side of t,he observer, the theodolite is in the face left condition. Normally, the face left condition is used in practice. The face left condition is, therefore, also known as the normal condition. The telescope is in the normal position. It is also called the direct condition

Face Right Condition : If the vertical circle is on the right side of the observer, the theodolite is in the face right condition. The telescope is in the inverted position. It is also called the reverse condition.

2) Direct and deflection angle

Direct angle : An angle measured directly between two lines, as distinguished in transit traverse from a deflection angle.

Deflection angle :
In surveying, a horizontal angle measured from prolongation of the preceding transit line to the next line; recorded as “right” if clockwise rotation and “left” if counterclockwise.

3) Angle and bearing
A bearing is a direction. Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270

An angle is a measure of rotation from one ray to another ray with the same endpoint. Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.

4) Horizontal and vertical axis in theodolite
Horizontal Axis : It is the line passing through journals which fit into the bearings at the top of the standards. The telescope is turned about the horizontal axis when measuring vertical angles. The horizontal axis is also known as the trunnion axis, elevation axis or transverse axis.

Vertical axis : It is the direction of gravity and is indicated by a freely suspended plumb bob. In case of perfectly adjusted theodolite, it is the line passing through the centre of the inner spindle, outer spindle and the bearing in the tribach.

5) Spire test and collimation in azimuth test

spire test - it is test for the adjustment of the standards and the line of of sight should be perpendicular to the vertical axis

Collimation - it's line of sight should be horizontal axis

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A) Face Left and Face right

Face right is when the vertical circle of an instrument is in the right side of the observer

Face left is when vertical circle of an instrument is in left side of the observer while taking the readings during survey.

B) Direct and deflection angle

Direct Angle

An angle measured directly between two lines, as distinguished in transit traverse from a deflection angle.

Deflection angle

A deflection angle should never be measured without double centering the instrument, because the error caused by the line of sight not being normal to the horizontal axis of the instrument may be too large to be tolerated. Moreover, the angular error of closure should not exceed the estimated standard deviation for observing an angle from a single setup times the square root of the number of instrument stations. In practice, this estimated standard deviation in angular measurement is usually taken equal to 0.5 to 1.0 times the least count of the instrument used in measuring the angles. If the error exceeds the permissible limit, then observation should be repeated till permissible limit has been achieved.

Deflection angle method of traversing is being generally used for open looped closed traverse. It is most useful for the location survey of linear engineering works such as highways, railways, canals and pipelines etc.

C) Angle and Bearing

A bearing is a direction. Bearings are measured clockwise from north, so north is zero degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.

In trigonometry, an angle is a measure of rotation from one ray to another ray with the same endpoint. Angles are measured counter clockwise from the positive x-axis. The positive x-axis is zero degrees, positive y-axis is 90 degrees, etc.

In geometry, angles are measured without regard for direction or orientation. Either ray can be zero and the angle is always positive and between zero and 180 degrees. Angles greater than 180 degrees are called reflex angles.

D) Horizontal and vertical axes of theodolites

Horizontal angle

These angle are used to determine the bearings and directions in control surveys, for locating detail when mapping and for setting out all types of structure.

Vertical angle
These angles are used to determine the heights of points and to calculate slope corrections

E) Spire test and Collimation in Azimuth test

Spire test

The test conducted to bring the horizontal axis perpendicular to vertical axis is called the spire test. This condition ensures that the motion of telescope is in a vertical plane.

Desired relation : horizontal axis should be perpendicular to vertical axis.

Object : the object of adjustment is to make the horizontal axis is perpendicular to vertical axis so that horizontal axis is perfectly horizontal when instrument is levelled.

Necessity : if adjustment of LOS is done, LOS will move in the plane when telescope is plunged, this ensures that the plane will be the vertical plane.

Collimation
2 adjustment which are the horizontal collimation adjustment and vertical collimation adjustment. The purpose of horizontal collimation adjusting is to make the line of sight perpendicular to the horizontal axis of telescope. for vertical collimation adjustment, the purpose is to make the vertical crossline of reticle lie in a plane perpendicular to horizontal axis of the telescope.

# data[].attributes.body
Axis of Theodolite (horizontal and vertical axes