HOW TO READ ANGLE IN A VERNIER THEODOLITE

 

Who invented theodolite?

This theodolite, often call the Great Theodolite, was created by Jesse Ramsden, a famous British instrument maker. 
The Great Theodolite, which also is known as Ramsden's Theodolite, was kept secure for 150 years at the Ordnance Survey in Southampton, 





What is theodolite angle?
The theodolite is an instrument constructed to measure angles in the horizontal and the vertical plane. In order to be able to do this, a horizontal (HZ) circle and a vertical (V) circle are located inside the instrument. Both circles are graduated and the scales on them go from 0° to 360°


Vernier theodolite replaces compass for angular measurements. It can also be used for measurement of vertical angles.

 Its least count varies from 10” to 20” depending on the type of Vernier used in it.

The size of Theodolites is defined according to the diameter of its main scale, such as a 10 cm theodolite which means that the diameter of its main scale is 10cm. 

In a survey, 8 cm to 12 cm theodolites are generally used.

  • Transit Theodolites: 

  • A theodolite is named a transit theodolite once its telescope will be transited i.e. rotated through a whole revolution regarding its horizontal axis within the vertical plane.

The Vernier theodolite is also known as a transit theodolite. 

  • Non-Transit Theodolite:

  •  In this kind, the telescope cannot be transited.

The value of 1big division on the vernier plate is 1'. 

The big division is divided into three small division then the value of 1 small division will be 1'÷3 or 60" ÷3=20". 

vernier A and B are exactly set to 0° and 180°. 

Upper clamp is tightly fixed, lower one is loosened and telescope is directed towards A and bisect the ranging rod at A. 

Tightened the lower clamp and turn the lower tangent screw to perfectly bisect ranging rod at A. with upper tangent screw.


TO KNOW ABOUT HOW TO READ AN


ANGLE IN A VERNIER THEODOLITE  WATCH THE BELOW VIDEO



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